What are the stages of kidney disease?

Your GFR is the best indicator of how well your kidneys are working. In 2002, the National Kidney Foundation published treatment guidelines that identified five stages of CKD based on declining GFR measurements. The guidelines recommend different actions based on the stage of kidney disease.

• Increased risk of CKD. A GFR of 90 or above is considered normal. Even with a normal GFR, you may be at increased risk for developing CKD if you have diabetes, high blood pressure, or a family history of kidney disease. The risk increases with age: People over 65 are more than twice as likely to develop CKD as people between the ages of 45 and 65. African Americans also have a higher risk of developing CKD.
  
  
• Stage 1: Kidney damage with normal GFR (90 or above). Kidney damage may be detected before the GFR begins to decline. In this first stage of kidney disease, the goals of treatment are to slow the progression of CKD and reduce the risk of heart and blood vessel disease.
  
  
• Stage 2: Kidney damage with mild decrease in GFR (60 to 89). When kidney function starts to decline, your health care provider will estimate the progression of your CKD and continue treatment to reduce the risk of other health problems.
  
  
• Stage 3: Moderate decrease in GFR (30 to 59). When CKD has advanced to this stage, anemia and bone problems become more common. Work with your health care provider to prevent or treat these complications.
  
  
• Stage 4: Severe reduction in GFR (15 to 29). Continue following the treatment for complications of CKD and learn as much as you can about the treatments for kidney failure. Each treatment requires preparation. If you choose hemodialysis, you will need to have a procedure to make a vein in your arm larger and stronger for repeated needle insertions. For peritoneal dialysis, you will need to have a catheter placed in your abdomen. Or you may want to ask family or friends to consider donating a kidney for transplantation.
  
  
• Stage 5: Kidney failure (GFR less than 15). When the kidneys do not work well enough to maintain life, you will need dialysis or a kidney transplant.
  
  

In addition to tracking your GFR, blood tests can show when substances in your blood are out of balance. If phosphorus or potassium levels start to climb, a blood test will prompt your health care provider to address these issues before they permanently affect your health.

How do kidneys fail?

Many factors that influence the speed of kidney failure are not completely understood. Researchers are still studying how protein in the diet and cholesterol levels in the blood affect kidney function.

Acute Renal Failure

Some kidney problems happen quickly, like an accident that injures the kidneys. Losing a lot of blood can cause sudden kidney failure. Some drugs or poisons can make your kidneys stop working. These sudden drops in kidney function are called acute renal failure (ARF).

ARF may lead to permanent loss of kidney function. But if your kidneys are not seriously damaged, acute renal failure may be reversed.

Chronic Kidney Disease

Most kidney problems, however, happen slowly. You may have “silent” kidney disease for years. Gradual loss of kidney function is called chronic kidney disease (CKD) or chronic renal insufficiency. People with CKD may go on to permanent kidney failure. They also have a high risk of dying from a stroke or heart attack.

End-Stage Renal Disease

Total or nearly total and permanent kidney failure is called end-stage renal disease (ESRD). People with ESRD must undergo dialysis or transplantation to stay alive.

Why do kidneys fail?

Most kidney diseases attack the nephrons, causing them to lose their filtering capacity. Damage to the nephrons may happen quickly, often as the result of injury or poisoning. But most kidney diseases destroy the nephrons slowly and silently. Only after years or even decades will the damage become apparent. Most kidney diseases attack both kidneys simultaneously.

The two most common causes of kidney disease are diabetes and high blood pressure. If your family has a history of any kind of kidney problems, you may be at risk for kidney disease.

Diabetic Nephropathy

Diabetes is a disease that keeps the body from using glucose (sugar) as it should. If glucose stays in your blood instead of breaking down, it can act like a poison. Damage to the nephrons from unused glucose in the blood is called diabetic nephropathy. If you keep your blood glucose levels down, you can delay or prevent diabetic nephropathy.

High Blood Pressure

High blood pressure can damage the small blood vessels in your kidneys. The damaged vessels cannot filter wastes from your blood as they are supposed to.

Your doctor may prescribe blood pressure medication. Blood pressure medicines called angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs) have been found to protect the kidneys even more than other medicines that lower blood pressure to similar levels. The National Heart, Lung, and Blood Institute (NHLBI), one of the National Institutes of Health, recommends that people with diabetes or reduced kidney function should keep their blood pressure below 130/80 mm Hg.

Glomerular Diseases

Several different types of kidney disease are grouped together under this category, including autoimmune diseases, infection-related diseases, and sclerotic diseases. As the name indicates, glomerular diseases attack the tiny blood vessels (glomeruli) within the kidney. The most common primary glomerular diseases include membranous nephropathy, IgA nephropathy, and focal segmental glomerulosclerosis. Protein, blood, or both in the urine are often the first signs of these diseases. They can slowly destroy kidney function. Blood pressure control is important with any kidney disease. Treatments for glomerular diseases may include immunosuppressive drugs or steroids to reduce inflammation and proteinuria, depending on the specific disease.

Inherited and Congenital Kidney Diseases

Some kidney diseases result from hereditary factors. Polycystic kidney disease (PKD), for example, is a genetic disorder in which many cysts grow in the kidneys. PKD cysts can slowly replace much of the mass of the kidneys, reducing kidney function and leading to kidney failure.

Some kidney problems may show up when a child is still developing in the womb. Examples include autosomal recessive PKD, a rare form of PKD, and other developmental problems that interfere with the normal formation of the nephrons. The signs of kidney disease in children vary. A child may grow unusually slowly, may vomit often, or may have back or side pain. Some kidney diseases may be “silent” for months or even years.

If your child has a kidney disease, your child’s doctor should find it during a regular checkup. Be sure your child sees a doctor regularly. The first sign of a kidney problem may be high blood pressure, a low number of red blood cells (anemia), or blood or protein in the child’s urine. If the doctor finds any of these problems, further tests may be necessary, including additional blood and urine tests or radiology studies. In some cases, the doctor may need to perform a biopsy—removing a tiny piece of the kidney to examine under a microscope.

Some hereditary kidney diseases may not be detected until adulthood. The most common form of PKD was once called "adult PKD" because the symptoms of high blood pressure and renal failure usually do not occur until patients are in their twenties or thirties. But with advances in diagnostic imaging technology, doctors have found cysts in children and adolescents before any symptoms appear.

Other Causes of Kidney Disease

Poisons and trauma, for example a direct and forceful blow to your kidneys, can lead to kidney disease.

Some over-the-counter medicines can be poisonous to your kidneys if taken regularly over a long period of time. Products that combine aspirin, acetaminophen, and other medicines such as ibuprofen have been found to be the most dangerous to the kidneys. If you take painkillers regularly, check with your doctor to make sure you are not putting your kidneys at risk.

What do my kidneys do?

The kidneys remove wastes and extra water from the blood to form urine. Urine flows from the kidneys to the bladder through the ureters.

Your kidneys are bean-shaped organs, each about the size of your fist. They are located near the middle of your back, just below the rib cage. The kidneys are sophisticated reprocessing machines. Every day, your kidneys process about 200 quarts of blood to sift out about 2 quarts of waste products and extra water. The waste and extra water become urine, which flows to your bladder through tubes called ureters. Your bladder stores urine until you go to the bathroom.

The wastes in your blood come from the normal breakdown of active tissues and from the food you eat. Your body uses the food for energy and self-repair. After your body has taken what it needs from the food, waste is sent to the blood. If your kidneys did not remove these wastes, the wastes would build up in the blood and damage your body.

The actual filtering occurs in tiny units inside your kidneys called nephrons. Every kidney has about a million nephrons. In the nephron, a glomerulus—which is a tiny blood vessel, or capillary—intertwines with a tiny urine-collecting tube called a tubule. A complicated chemical exchange takes place, as waste materials and water leave your blood and enter your urinary system.

At first, the tubules receive a combination of waste materials and chemicals that your body can still use. Your kidneys measure out chemicals like sodium, phosphorus, and potassium and release them back to the blood to return to the body. In this way, your kidneys regulate the body’s level of these substances. The right balance is necessary for life, but excess levels can be harmful.

[d]

In the nephron (left), tiny blood vessels intertwine with urine-collecting tubes. Each kidney contains about 1 million nephrons.

In addition to removing wastes, your kidneys release three important hormones:

• erythropoietin (eh-RITH-ro-POY-eh-tin), or EPO, which stimulates the bone marrow to make red blood cells
  
  
• renin (REE-nin), which regulates blood pressure
  
  
• calcitriol (kal-suh-TRY-ul), the active form of vitamin D, which helps maintain calcium for bones and for normal chemical balance in the body

What medical tests will my doctor use to detect kidney disease?

Since you can have kidney disease without any symptoms, your doctor may first detect the condition through routine blood and urine tests. The National Kidney Foundation recommends three simple tests to screen for kidney disease: a blood pressure measurement, a spot check for protein or albumin in the urine (proteinuria), and a calculation of glomerular filtration rate (GFR) based on a serum creatinine measurement. Measuring urea nitrogen in the blood provides additional information.

Blood Pressure Measurement

High blood pressure can lead to kidney disease. It can also be a sign that your kidneys are already impaired. The only way to know whether your blood pressure is high is to have a health professional measure it with a blood pressure cuff. The result is expressed as two numbers. The top number, which is called the systolic pressure, represents the pressure when your heart is beating. The bottom number, which is called the diastolic pressure, shows the pressure when your heart is resting between beats. Your blood pressure is considered normal if it stays below 120/80 (expressed as “120 over 80”). The NHLBI recommends that people with kidney disease use whatever therapy is necessary, including lifestyle changes and medicines, to keep their blood pressure below 130/80.

Microalbuminuria and Proteinuria

Healthy kidneys take wastes out of the blood but leave protein. Impaired kidneys may fail to separate a blood protein called albumin from the wastes. At first, only small amounts of albumin may leak into the urine, a condition known as microalbuminuria, a sign of deteriorating kidney function. As kidney function worsens, the amount of albumin and other proteins in the urine increases, and the condition is called proteinuria. Your doctor may test for protein using a dipstick in a small sample of your urine taken in the doctor’s office. The color of the dipstick indicates the presence or absence of proteinuria.

A more sensitive test for protein or albumin in the urine involves laboratory measurement and calculation of the protein-to-creatinine or albumin-to-creatinine ratio. This test should be used to detect kidney disease in people at high risk, especially those with diabetes. If your first laboratory test shows high levels of protein, another test should be done 1 to 2 weeks later. If the second test also shows high levels of protein, you have persistent proteinuria and should have additional tests to evaluate your kidney function.

Glomerular Filtration Rate (GFR) Based on Creatinine Measurement

GFR is a calculation of how efficiently the kidneys are filtering wastes from the blood. A traditional GFR calculation requires an injection into the bloodstream of a substance that is later measured in a 24-hour urine collection. Recently, scientists found they could calculate GFR without an injection or urine collection. The new calculation requires only a measurement of the creatinine in a blood sample.

Creatinine is a waste product in the blood created by the normal breakdown of muscle cells during activity. Healthy kidneys take creatinine out of the blood and put it into the urine to leave the body. When kidneys are not working well, creatinine builds up in the blood.

In the lab, your blood will be tested to see how many milligrams of creatinine are in one deciliter of blood (mg/dL). Creatinine levels in the blood can vary, and each laboratory has its own normal range, usually 0.6 to 1.2 mg/dL. If your creatinine level is only slightly above this range, you probably will not feel sick, but the elevation is a sign that your kidneys are not working at full strength. One formula for estimating kidney function equates a creatinine level of 1.7 mg/dL for most men and 1.4 mg/dL for most women to 50 percent of normal kidney function. But because creatinine values are so variable and can be affected by diet, a GFR calculation is more accurate for determining whether a person has reduced kidney function.

The new GFR calculation uses the patient’s creatinine measurement along with weight, age, and values assigned for sex and race. Some medical laboratories may make the GFR calculation when a creatinine value is measured and include it on their lab report.

Blood Urea Nitrogen (BUN)

Blood carries protein to cells throughout the body. After the cells use the protein, the remaining waste product is returned to the blood as urea, a compound that contains nitrogen. Healthy kidneys take urea out of the blood and put it in the urine. If your kidneys are not working well, the urea will stay in the blood.

A deciliter of normal blood contains 7 to 20 milligrams of urea. If your BUN is more than 20 mg/dL, your kidneys may not be working at full strength. Other possible causes of an elevated BUN include dehydration and heart failure.

Additional Tests for Kidney Disease

If blood and urine tests indicate reduced kidney function, your doctor may recommend additional tests to help identify the cause of the problem.

Chronic kidney failure

Chronic kidney failure is a slowly progressive decline (months to years) in the kidneys' ability to filter metabolic waste from the blood.

Many diseases can irreversibly damage or injure the kidneys. Acute kidney failure can become chronic if kidney function does not recover after treatment. Therefore, anything that can cause acute kidney failure can cause chronic kidney failure. However, the most common cause of chronic kidney failure is diabetes mellitus, followed by high blood pressure (hypertension). Both of these conditions directly harm the kidneys' small blood vessels. Other causes of chronic kidney failure include urinary tract obstruction; kidney abnormalities (such as polycystic kidney disease and glomerulonephritis); and autoimmune disorders (such as systemic lupus erythematosus), in which antibodies damage the tiny blood vessels (glomeruli) and the tiny tubes (tubules) of the kidneys.

Symptoms

Symptoms may develop slowly or evolve from acute kidney failure. A person with mild to moderate kidney failure may have only mild symptoms despite the increase in the levels of urea and other metabolic waste products in the blood. At this stage, the person may need to urinate several times during the night (nocturia), because the kidneys cannot absorb water from the urine to reduce the volume and concentrate it as normally occurs during the night.

As kidney failure progresses and metabolic wastes build up in the blood, the person may feel fatigued and generally weak and may become less mentally alert. These symptoms progress as the blood becomes more acidic, a condition called acidosis. A loss of appetite and shortness of breath can result. Fatigue and generalized weakness may also be attributed in part to a decline in red blood cell production and the resulting anemia. People with chronic kidney failure tend to bruise easily or bleed for an unusually long time after cuts or other injuries. Chronic kidney failure also diminishes the body's ability to fight infections.

As metabolic wastes build up in the blood, damage to muscles and nerves can cause muscle twitches, muscle weakness, cramps, and pain. The person may also feel a pins-and-needles sensation in the arms and legs and may lose sensation in certain areas of the body. Encephalopathy, a condition in which the brain malfunctions, may ensue from the buildup of metabolic waste products in the blood. This condition may lead to confusion, lethargy, and seizures.

High blood pressure often develops in people who have kidney failure, because the diseased kidneys produce hormones that raise blood pressure. In addition, diseased kidneys cannot excrete excess salt and water. Salt and fluid retention can lead to heart failure, which may cause shortness of breath. The sac that surrounds the heart (pericardium) may become inflamed (pericarditis) as metabolic waste products accumulate. This complication may cause chest pain and low blood pressure. The level of triglycerides in the blood is often elevated, which, along with hypertension, increases the risk for atherosclerosis. The buildup of metabolic waste in the blood also causes nausea, vomiting, and an unpleasant taste in the mouth, which may lead to malnutrition and weight loss. People who have advanced chronic kidney failure commonly develop gastrointestinal ulcers and bleeding. The skin may turn yellow-brown, and occasionally, the concentration of urea is so high that it crystallizes from sweat, forming a white powder on the skin. Some people with chronic kidney failure itch all over their body.

The formation and maintenance of bone tissue may be impaired (renal osteodystrophy) if certain conditions that accompany chronic kidney failure are present for a long time. These conditions include a high level of parathyroid hormone, low concentration of calcitriolSome Trade Names
ROCALTROL
(the active form of vitamin D) in the blood, impaired absorption of calcium, and a high concentration of phosphate in the blood. Renal osteodystrophy may lead to bone pain and an increased risk of fractures.

Diagnosis

Blood tests are essential and show increased levels of urea and creatinine, metabolic waste products that are normally filtered out by the kidneys. Typically, the blood becomes moderately acidic. The level of potassium in the blood is normal or only slightly increased but can become dangerously high when kidney failure reaches an advanced stage or if a person ingests large amounts of potassium. Usually, the person has some decline in red blood cell count (anemia). The level of triglycerides in the blood is likely to be elevated. The calcium and calcitriolSome Trade Names
ROCALTROL
levels decrease, and the phosphate and parathyroid hormone levels increase.

Urine volume often stays about the same, regardless of the amount of fluid consumed. Analysis of the urine may detect many abnormalities, including protein and abnormal cells.

Determining a precise cause becomes increasingly difficult as the kidney failure reaches an advanced stage. A kidney biopsy may be the most accurate test, but it is not recommended if results of an ultrasound show that the kidneys are small and scarred.

Prognosis and Treatment

Ultimately, chronic kidney failure progresses in most people regardless of treatment. It is fatal if not treated. Survival when kidney failure is severe (sometimes called end-stage kidney failure) is usually limited to several months in people who are not treated, but those who are treated with dialysis can live many years. The doctor must pay attention to conditions that can cause or worsen kidney failure and consequences of the kidney failure that might adversely affect overall health. For example, infections are treated promptly with antibiotics, and any obstructions in the urinary tract are removed or relieved.

The rate of decline in kidney function depends somewhat on the underlying disorder causing the kidney failure. For example, controlling the level of sugar in the blood as well as hypertension in people with diabetes substantially slows deterioration in kidney function. Drugs called angiotensin-converting enzyme (ACE) inhibitors and also angiotensin receptor blockers may decrease the rate of decline in kidney function in some people with chronic kidney failure.

Meticulous attention to diet helps control a number of potential problems. Sometimes mild acidosis can be controlled by increasing the intake of carbohydrates and reducing proteins. However, moderate or severe acidosis may require treatment with sodium bicarbonate. The decline in kidney function can be slowed slightly by restricting the amount of protein consumed daily. The person needs to consume sufficient carbohydrates to offset the reduction in protein. The triglyceride level may be lowered somewhat by limiting fat in the diet. Drugs such as gemfibrozilSome Trade Names
LOPID
may be required to reduce the triglyceride level.

The intake of salt (sodium) usually does not have to be restricted unless fluid accumulates and is retained in the tissues or high blood pressure develops. A person with heart failure needs to restrict the intake of sodium. Diuretics may also relieve symptoms of heart failure, even when kidney function is poor, but dialysis may be needed to remove the excess fluid.

During chronic kidney failure, changes in thirst usually determine how much water is consumed. Occasionally, water intake needs to be restricted to prevent the sodium concentration in the blood from becoming too low. Foods that are extremely high in potassium, such as salt substitutes, must be avoided, and foods that are somewhat high in potassium, such as dates and figs, should not be consumed in excess. A high potassium level in the blood increases the risk of abnormal heart rhythms and cardiac arrest. If the potassium level becomes too high, drugs may help, but emergency dialysis may be required.

The elevated phosphorus level in the blood can cause deposits of calcium and phosphorus to form in tissues, including the blood vessels. Restricting the intake of foods high in phosphorus, such as dairy products, liver, legumes, nuts, and most soft drinks, lowers the phosphate concentration in the blood. Drugs that bind phosphate, such as calcium carbonateSome Trade Names
TUMS
CALTRATE
OSCAL
and calcium acetate, taken by mouth, may also lower the phosphorus level in the blood.

The anemia caused by kidney failure responds to the drugs erythropoietinSome Trade Names
EPOGEN
PROCRIT
or darbepoietin. Blood transfusions are given only if the anemia is severe, is causing symptoms, and does not respond to erythropoietinSome Trade Names
EPOGEN
PROCRIT
or darbepoietin. Doctors also look for and treat other causes of anemia, particularly dietary deficiencies of iron, folic acid (folate), and vitamin B₁₂ or excesses of aluminum in the body. Most people receiving erythropoietinSome Trade Names
EPOGEN
PROCRIT
or darbepoietin regularly need to be given iron intravenously to prevent iron deficiency, which impairs the body's response to these drugs. Anemia often requires more aggressive treatment in older people, because they are more likely to have heart disease, which can be aggravated by the anemia. The tendency to bleed can be temporarily suppressed by transfusions of platelets or fresh frozen plasma or by such drugs as desmopressinSome Trade Names
DDAVP
STIMATE
or estrogensSome Trade Names
PREMARIN
. Such treatment may be needed after an injury or before a surgical procedure or a tooth extraction.

A moderate or severe increase in blood pressure is treated with blood pressure drugs to prevent further impairment of heart and kidney function.

When the treatments for chronic kidney failure are no longer effective, the only option is long-term dialysis or kidney transplantation (see Transplantation: Kidney Transplantation). Despite the advent of dialysis, most people with advanced kidney failure die within 5 to 10 years. End-of-life care is important (see Death and Dying: Introduction).

Kidney Disease (High Blood Pressure Related) Glossary of Terms

ACE inhibitors : A drug that inhibits ACE (angiotensin converting enzyme) which is important to the formation of angiotensin II. Angiotensin II causes arteries in the body to constrict and thereby raises the blood pressure. ACE inhibitors lower the blood pressure by inhibiting the formation of angiotensin II. This relaxes the arteries. Relaxing the arteries not only lowers blood pressure, but also improves the pumping efficiency of a failing heart and improves cardiac output in patients with heart failure. ACE inhibitors are therefore used for blood pressure control and congestive heart failure .
See the entire definition of ACE inhibitors

Alcohol: An organic chemical in which one or more hydroxyl (OH) groups are attached to carbon (C) atoms in place of hydrogen (H) atoms. Common alcohols include ethyl alcohol or ethanol (found in alcoholic beverages), methyl alcohol or methanol (can cause blindness) and propyl alcohol or propanol (used as a solvent and antiseptic ). Rubbing alcohol is a mixture of acetone , methyl isobutyl ketone, and ethyl alcohol. In everyday talk, alcohol usually refers to ethanol as, for example, in wine, beer, and liquor. It can cause changes in behavior and be addictive.
See the entire definition of Alcohol

Angiotensin: A family of peptides (smaller than proteins) that act as vasoconstrictors to narrow blood vessels.

Blood: The familiar red fluid in the body that contains white and red blood cells, platelets, proteins, and other elements. The blood is transported throughout the body by the circulatory system. Blood functions in two directions: arterial and venous. Arterial blood is the means by which oxygen and nutrients are transported to tissues while venous blood is the means by which carbon dioxide and metabolic by-products are transported to the lungs and kidneys, respectively, for removal from the body.

Blood pressure: The blood pressure is the pressure of the blood within the arteries. It is produced primarily by the contraction of the heart muscle. It's measurement is recorded by two numbers. The first (systolic pressure) is measured after the heart contracts and is highest. The second (diastolic pressure) is measured before the heart contracts and lowest. A blood pressure cuff is used to measure the pressure. Elevation of blood pressure is called "hypertension".

Caffeine: A stimulant found naturally in coffee beans, tea leaves, cocoa beans (chocolate) and kola nuts (cola) and added to soft drinks, foods, and medicines. A cup of coffee has 100-250 milligrams of caffeine. Black tea brewed for 4 minutes has 40-100 milligrams. Green tea has one-third as much caffeine as black tea.
See the entire definition of Caffeine

Creatinine: A chemical waste molecule that is generated from muscle metabolism. Creatinine is produced from creatine, a molecule of major importance for energy production in muscles. Approximately 2% of the body's creatine is converted to creatinine every day. Creatinine is transported through the bloodstream to the kidneys. The kidneys filter out most of the creatinine and dispose of it in the urine.
See the entire definition of Creatinine

Diabetes: Refers to diabetes mellitus or, less often, to diabetes insipidus . Diabetes mellitus and diabetes insipidus share the name "diabetes" because they are both conditions characterized by excessive urination (polyuria).
See the entire definition of Diabetes

Dialysis: The process of cleansing the blood by passing it through a special machine. Dialysis is necessary when the kidneys are not able to filter the blood. Dialysis allows patients with kidney failure a chance to live productive lives. There are two types of dialysis: hemodialysis and peritoneal dialysis. Each type of dialysis has advantages and disadvantages. Patients can often choose the type of long term dialysis that best matches their needs.

Diastolic: Referring to the time when the heart is in a period of relaxation and dilatation (expansion).
See the entire definition of Diastolic

Disease: Illness or sickness often characterized by typical patient problems (symptoms) and physical findings (signs). Disruption sequence: The events that occur when a fetus that is developing normally is subjected to a destructive agent such as the rubella (German measles) virus.

Diuretic: Anything that promotes the formation of urine by the kidney. (The word "diuretic" comes from a combination of the Greek "dia-", thoroughly + "ourein", to urinate = to urinate thoroughly).
See the entire definition of Diuretic

End-stage renal disease: ESRD. Chronic irreversible renal failure.

Enzyme: A protein (or protein-based molecule) that speeds up a chemical reaction in a living organism. An enzyme acts as catalyst for specific chemical reactions , converting a specific set of reactants (called substrates) into specific products. Without enzymes, life as we know it would not exist.
See the entire definition of Enzyme

ESRD: End-stage renal disease.

Glomerular: Pertaining to the glomerulus, a tiny structure in the kidney that filters the blood to form urine.

Health: As officially defined by the World Health Organization, a state of complete physical, mental, and social well-being, not merely the absence of disease or infirmity.

Heart: The muscle that pumps blood received from veins into arteries throughout the body. It is positioned in the chest behind the sternum (breastbone; in front of the trachea, esophagus, and aorta; and above the diaphragm muscle that separates the chest and abdominal cavities. The normal heart is about the size of a closed fist, and weighs about 10.5 ounces. It is cone-shaped, with the point of the cone pointing down to the left. Two-thirds of the heart lies in the left side of the chest with the balance in the right chest.
See the entire definition of Heart

Heart disease: Any disorder that affects the heart. Sometimes the term "heart disease" is used narrowly and incorrectly as a synonym for coronary artery disease. Heart disease is synonymous with cardiac disease but not with cardiovascular disease which is any disease of the heart or blood vessels. Among the many types of heart disease, see, for example: Angina; Arrhythmia; Congenital heart disease; Coronary artery disease (CAD); Dilated cardiomyopathy; Heart attack (myocardial infarction); Heart failure; Hypertrophic cardiomyopathy; Mitral regurgitation; Mitral valve prolapse; and Pulmonary stenosis.

High blood pressure : Also known as hypertension, high blood pressure is, by definition, a repeatedly elevated blood pressure exceeding 140 over 90 mmHg -- a systolic pressure above 140 with a diastolic pressure above 90.
See the entire definition of High blood pressure

Hypertension: High blood pressure , defined as a repeatedly elevated blood pressure exceeding 140 over 90 mmHg -- a systolic pressure above 140 with a diastolic pressure above 90.
See the entire definition of Hypertension

Kidney: One of a pair of organs located in the right and left side of the abdomen which clear "poisons" from the blood, regulate acid concentration and maintain water balance in the body by excreting urine. The kidneys are part of the urinary tract. The urine then passes through connecting tubes called "ureters" into the bladder. The bladder stores the urine until it is released during urination.

What groups are at risk for kidney failure related to high blood pressure?

All racial groups have some risk of developing kidney failure from high blood pressure. African Americans, however, are more likely than Caucasians to have high blood pressure and to develop kidney problems from it—even when their blood pressure is only mildly elevated. In fact, African Americans are six times more likely than Caucasians to develop hypertension-related kidney failure.

People with diabetes also have a substantially increased risk for developing kidney failure. People who are at risk both because of their race and because of diabetes should have early management of high blood pressure.

The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), also part of NIH, sponsored the African American Study of Kidney Disease and Hypertension (AASK) to find effective ways to prevent high blood pressure and kidney failure in this population. The results, released in 2003, showed that an ACE inhibitor was better at slowing the progression of kidney disease in African Americans than either of two other drugs.

Hope Through Research

In recent years, researchers have learned a great deal about kidney disease. NIDDK sponsors several programs aimed at understanding kidney failure and finding treatments to stop its progression.

NIDDK's Division of Kidney, Urologic, and Hematologic Diseases supports basic research into normal kidney function and the diseases that impair normal function at the cellular and molecular levels, including diabetes, high blood pressure, glomerulonephritis, and polycystic kidney disease .

How can I prevent high blood pressure from damaging my kidneys?

If you have kidney damage, you should keep your blood pressure below 130/80. The National Heart, Lung, and Blood Institute (NHLBI), one of the National Institutes of Health (NIH), recommends that people with kidney disease use whatever therapy is necessary, including lifestyle changes and medicines, to keep their blood pressure below 130/80.

How can I control my blood pressure?

NHLBI has found that five lifestyle changes can help control blood pressure:

• Maintain your weight at a level close to normal. Choose fruits, vegetables, grains, and low-fat dairy foods.
• Limit your daily sodium (salt) intake to 2,000 milligrams or lower if you already have high blood pressure. Read nutrition labels on packaged foods to learn how much sodium is in one serving. Keep a sodium diary.
• Get plenty of exercise, which means at least 30 minutes of moderate activity, such as walking, most days of the week.
• Avoid consuming too much alcohol. Men should limit consumption to two drinks (two 12-ounce servings of beer or two 5-ounce servings of wine or two 1.5-ounce servings of "hard" liquor) a day. Women should have no more than a single serving on a given day because metabolic differences make women more susceptible to the effects of alcohol.
• Limit caffeine intake.

Are there medicines that can help?

Many people need medicine to control high blood pressure. Two groups of medications called ACE (angiotensin-converting enzyme) inhibitors and ARBs (angiotensin receptor blockers) lower blood pressure and have an added protective effect on the kidney in people with diabetes. Additional studies have shown that ACE inhibitors and ARBs also reduce proteinuria and slow the progression of kidney damage in people who do not have diabetes. You may need to take a combination of two or more blood pressure medicines to stay below 130/80. Your doctor may also prescribe a diuretic in addition to your ACE inhibitor or ARB. Diuretics are also called "water pills" because they help you urinate and get rid of excess fluid in your body.

How will I know whether I have kidney damage?

Kidney damage, like hypertension, can be unnoticeable and detected only through medical tests. Blood tests will show whether your kidneys are removing wastes efficiently. Your doctor should order tests to measure your serum creatinine. Having too much creatinine in your blood is a sign that you have kidney damage. The doctor should use the serum creatinine to estimate the main kidney function called glomerular filtration rate, or GFR.

Another sign is proteinuria, or protein in your urine. Proteinuria has also been shown to be associated with heart disease and damaged blood vessels.

How will I know whether I have high blood pressure?

Most people with high blood pressure have no symptoms. The only way to know whether your blood pressure is high is to have a health professional measure it with a blood pressure cuff. The result is expressed as two numbers. The top number, which is called the systolic pressure, represents the pressure when your heart is beating. The bottom number, which is called the diastolic pressure, shows the pressure when your heart is resting between beats. Your blood pressure is considered normal if it stays below 120/80 (expressed as "120 over 80"). People with a systolic blood pressure of 120 to 139 or a diastolic blood pressure of 80 to 89 are considered prehypertensive and should adopt health-promoting lifestyle changes to prevent diseases of the heart and blood vessels. If your systolic blood pressure is consistently 140 or higher or your diastolic pressure is 90 or higher, you have high blood pressure and should talk with your doctor about the best ways to lower it.

How does high blood pressure hurt my kidneys?

High blood pressure makes your heart work harder and, over time, can damage blood vessels throughout your body. If the blood vessels in your kidneys are damaged, they may stop removing wastes and extra fluid from your body. The extra fluid in your blood vessels may then raise blood pressure even more. It's a dangerous cycle.

High blood pressure is one of the leading causes of kidney failure , also commonly called end-stage renal disease (ESRD). People with kidney failure must either receive a kidney transplant or go on dialysis. Every year, high blood pressure causes more than 25,000 new cases of kidney failure in the United States.

What is high blood pressure?

Hypertension can result from too much fluid in normal blood vessels or from normal fluid in narrow blood vessels. Blood pressure measures the force of blood against the walls of your blood vessels. Blood pressure that remains high over time is called hypertension. Extra fluid in your body increases the amount of fluid in your blood vessels and makes your blood pressure higher. Narrow or clogged blood vessels also raise your blood pressure.

If you have high blood pressure, see your doctor regularly.

Kidney Transplantation

What is kidney transplantation?

Kidney transplantation is a procedure that places a healthy kidney from another person into your body. This one new kidney does all the work that your two failed kidneys cannot do.

How does kidney transplantation work?

A surgeon places the new kidney inside your body between your upper thigh and abdomen. The surgeon connects the artery and vein of the new kidney to your artery and vein. Your blood flows through the new kidney and makes urine, just like your own kidneys did when they were healthy. The new kidney may start working right away or may take up to a few weeks to make urine. Your own kidneys are left where they are, unless they are causing infection or high blood pressure.

What do you need to get ready for kidney transplantation?

You may receive a kidney from a member of your family. This kind of donor is called a living-related donor. You may receive a kidney from a person who has recently died. This type of donor is called a cadaver donor. Sometimes a spouse or very close friend may donate a kidney. This kind of donor is called a living-unrelated donor.

It is very important for the donor's blood and tissues to closely match yours. This match will help prevent your body's immune system from fighting off, or rejecting, the new kidney. A lab will do special tests on blood cells to find out if your body will accept the new kidney.

How long does kidney transplantation take?

The time it takes to get a kidney varies. There are not enough cadaver donors for every person who needs a transplant. Because of this, you must be placed on a waiting list to receive a cadaver donor kidney. However, if a relative gives you a kidney, the transplant operation can be done sooner.

The surgery takes from 3 to 6 hours. The usual hospital stay may last from 10 to 14 days. After you leave the hospital, you will go to the clinic for regular follow-up visits.

If a relative or close friend gives you a kidney, he or she will probably stay in the hospital for one week or less.

What are the possible complications of a kidney transplantation?

Transplantation is not a cure. There is always a chance that your body will reject your new kidney, no matter how good the match. The chance of your body accepting the new kidney depends on your age, race, and medical condition.

Normally, 75 to 80 percent of transplants from cadaver donors are working one year after surgery. However, transplants from living relatives often work better than transplants from cadaver donors. This fact is because they are usually a closer match.

Your doctor will give you special drugs to help prevent rejection. These are called immunosuppressants. You will need to take these drugs every day for the rest of your life. Sometimes these drugs cannot stop your body from rejecting the new kidney. If this happens, you will go back to some form of dialysis and possibly wait for another transplant.

Treatment with these drugs may cause side effects. The most serious is that they weaken your immune system, making it easier for you get infections. Some drugs also cause changes in how you look. Your face may get fuller. You may gain weight or develop acne or facial hair. Not all patients have these problems, and makeup and diet can help.

Some of these drugs may cause problems such as cataracts, extra stomach acid, and hip disease. In a smaller number of patients, these drugs also may cause liver or kidney damage when used for a long period of time.

What is a good diet for a kidney transplant?

Diet for transplant patients is less limiting than it is for dialysis patients. You may still have to cut back on some foods, though. Your diet probably will change as your medicines, blood values, weight, and blood pressure change.

• You may need to count calories. Your medicine may give you a bigger appetite and cause you to gain weight.
• You may have to limit eating salty foods.
• Your medications may cause salt to be held in your body, leading to high blood pressure.
• You may need to eat less protein. Some medications cause a higher level of wastes to build up in your bloodstream.

What are the pros and cons of kidney transplants?

Kidney transplantation pros

• It works like a normal kidney.
• It helps you feel healthier.
• You have fewer diet restrictions.
• There's no need for dialysis.

Kidney transplantation cons

• It requires major surgery.
• You may need to wait for a donor.
• One transplant may not last a lifetime.
• Your body may reject the new kidney.
• You will have to take drugs for the rest of your life.

Peritoneal Dialysis

What is peritoneal dialysis?

Peritoneal dialysis is another procedure that replaces the work of your kidneys. It removes extra water, wastes, and chemicals from your body. This type of dialysis uses the lining of your abdomen to filter your blood. This lining is called the peritoneal membrane.

How does peritoneal dialysis work?

A cleansing solution, called dialysate, travels through a special tube into your abdomen. Fluid, wastes, and chemicals pass from tiny blood vessels in the peritoneal membrane into the dialysate. After several hours, the dialysate gets drained from your abdomen, taking the wastes from your blood with it. Then you fill your abdomen with fresh dialysate and the cleaning process begins again.

How do you get prepared for peritoneal dialysis?

Before your first treatment, a surgeon places a small, soft tube called a catheter into your abdomen. This catheter always stays there. It helps transport the dialysate to and from your peritoneal membrane.

What are the types of peritoneal dialysis?

There are three types of peritoneal dialysis:

1. Continuous Ambulatory Peritoneal Dialysis (CAPD)

CAPD is the most common type of peritoneal dialysis. It needs no machine. It can be done in any clean, well-lit place. With CAPD, your blood is always being cleaned. The dialysate passes from a plastic bag through the catheter and into your abdomen. The dialysate stays in your abdomen with the catheter sealed. After several hours, you drain the solution back into the bag. Then you refill your abdomen with fresh solution through the same catheter. Now the cleaning process begins again.

2. Continuous Cyclic Peritoneal Dialysis (CCPD)

CCPD is like CAPD except that a machine, which connects to your catheter, automatically fills and drains the dialysate from your abdomen. The machine does this at night while you sleep.

3. Intermittent Peritoneal Dialysis (IPD)

IPD uses the same type of machine as CCPD to add and drain the dialysate. IPD can be done at home, but it's usually done in the hospital. IPD treatments take longer than CCPD.

Who performs peritoneal dialysis?

CAPD is a form of self-treatment. It needs no machine and no partner. However, with IPD and CCPD, you need a machine and the help of a partner (family member, friend, or health professional).

How long does peritoneal dialysis take?

With CAPD, the dialysate stays in your abdomen for about 4 to 6 hours. The process of draining the dialysate and replacing fresh solution takes 30 to 40 minutes. Most people change the solution four times a day.

With CCPD, treatments last from 10 to 12 hours every night.

With IPD, treatments are done several times a week, for a total of 36 to 42 hours per week. Sessions may last up to 24 hours.

What are the possible complications of peritoneal dialysis?

Peritonitis, or infection of the peritoneum, can occur if the opening where the catheter enters your body gets infected. You can also get it if there is a problem connecting or disconnecting the catheter from the bags. Peritonitis can make you feel sick. It can cause a fever and stomach pain.

To avoid peritonitis, you must be careful to follow the procedure exactly. You must know the early signs of peritonitis. Look for reddening or swelling around the catheter. You should also note if your dialysate looks cloudy. It is important to report these signs to your doctor so that the peritonitis can be treated quickly to avoid serious problems.

What type of diet is beneficial to peritoneal dialysis?

Diet for peritoneal dialysis is slightly different than diet for hemodialysis.

• You may be able to have more salt and fluids.
• You may eat more protein.
• You may have different potassium restrictions.
• You may need to cut back on the number of calories you eat. This limitation is because the sugar in the dialysate may cause you to gain weight.

What are the pros and cons of each type of peritoneal dialysis?

CAPD Pros:

• You can perform treatment alone.
• You can do it at times you choose.
• You can do it in many locations.
• You don't need a machine.

CAPD Cons:

• It disrupts your daily schedule.

CCPD Pros:

• You can do it at night, mainly while you sleep.

CCPD Cons:

• You need a machine and help from a partner.

IPD Pros:

• Health professionals usually perform treatments.

IPD Cons:

• You may need to go to a hospital.
• It takes a lot of time.
• You need a machine.

Hemodialysis

What is hemodialysis?

Hemodialysis is a procedure that cleans and filters your blood. It rids your body of harmful wastes and extra salt and fluids. It also controls blood pressure and helps your body keep the proper balance of chemicals such as potassium, sodium, and chloride.

How does hemodialysis work?

Hemodialysis uses a dialyzer, or special filter, to clean your blood. The dialyzer connects to a machine. During treatment, your blood travels through tubes into the dialyzer. The dialyzer filters out wastes and extra fluids. Then the newly cleaned blood flows through another set of tubes and back into your body.

Getting ready for hemodialysis.

Before your first treatment, an access to your bloodstream must be made. The access provides a way for blood to be carried from your body to the dialysis machine and then back into your body. The access can be internal (inside the body -- usually under your skin) or external (outside the body).

Who performs hemodialysis?

Hemodialysis can be done at home or at a center. At a center, nurses or trained technicians perform the treatment. At home, you perform hemodialysis with the help of a partner, usually a family member or friend. If you decide to do home dialysis, you and your partner will receive special training.

How long does hemodialysis take?

Hemodialysis usually is done three times a week. Each treatment lasts from 2 to 4 hours. During treatment, you can read, write, sleep, talk, or watch TV.

What are possible complications of hemodialysis?

Side effects can be caused by rapid changes in your body's fluid and chemical balance during treatment. Muscle cramps and hypotension are two common side effects. Hypotension, a sudden drop in blood pressure, can make you feel weak, dizzy, or sick to your stomach.

It usually takes a few months to adjust to hemodialysis. You can avoid many of the side effects if you follow the proper diet and take your medicines as directed. You should always report side effects to your doctor. They often can be treated quickly and easily.

What foods are beneficial to hemodialysis treatment?

Hemodialysis and a proper diet help reduce the wastes that build up in your blood. A dietitian can help you plan meals according to your doctor's orders. When choosing foods, you should remember to:

• Eat balanced amounts of foods high in protein such as meat and chicken. Animal protein is better used by your body than the protein found in vegetables and grains.
• Watch the amount of potassium you eat. Potassium is a mineral found in salt substitutes, some fruits, vegetables, milk, chocolate, and nuts. Too much or too little potassium can be harmful to your heart.
• Limit how much you drink. Fluids build up quickly in your body when your kidneys aren't working. Too much fluid makes your tissues swell. It also can cause high blood pressure and heart trouble.
• Avoid salt. Salty foods make you thirsty and cause your body to hold water.
• Limit foods such as milk, cheese, nuts, dried beans, and soft drinks. These foods contain the mineral phosphorus. Too much phosphorus in your blood causes calcium to be pulled from your bones. Calcium helps keep bones strong and healthy. To prevent bone problems, your doctor may give you special medicines. You must take these medicines every day as directed.

What are the pros and cons of in-center hemodialysis?

Each person responds differently to similar situations. What may be a negative factor for one person may be positive for another. However, in general, the following are pros and cons for each type of hemodialysis.

Pros:

• You have trained professionals with you at all times.
• You can get to know other patients.

Cons:

• Treatments are scheduled by the center.
• You must travel to the center for treatment.

What are the pros and cons of home hemodialysis?

Pros:

• You can do it at the hours you choose. (But you still must do it as often as your doctor orders.)
• You don't have to travel to a center.
• You gain a sense of independence and control over your treatment.

Cons:

• Helping with treatments may be stressful to your family.
• You need training.
• You need space for storing the machine and supplies at home.

What are the treatments for kidney failure?

There are three options when treating kidney failure, which will be discussed in length in the following sections:

1. Hemodialysis
2. Peritoneal dialysis
3. Kidney transplant

What happens when your kidneys fail?

Healthy kidneys clean the blood by filtering out extra water and wastes. They also make hormones that keep your bones strong and blood healthy. When both of your kidneys fail, your body holds fluid. Your blood pressure rises. Harmful wastes build up in your body. Your body doesn't make enough red blood cells. You develop fatigue, nausea, and loss of appetite. When this happens, you need treatment to replace the work of your failed kidneys.

Treatment of Kidney Diseases

Some kidney diseases can be successfully treated and others progress to advanced kidney failure, requiring dialysis and/or transplantation.

For example, kidney infections and kidney stones can often be successfully treated. Chronic inflammation of the glomerulus (glomerulonephritis) is the most common kidney disease, which slowly progresses to kidney failure.

Your doctor may recommend certain medications or suggest a specific diet for you.

Diagnosis of Kidney Diseases

Your doctor will obtain a complete medical history and perform a physical exam. He or she may recommend blood tests and certain urine tests, which can provide much information about your kidney function.

Symptoms of Kidney Diseases

Although many forms of kidney disease do not produce symptoms until late in the course of the disease, there are at least six warning signs that may indicate kidney disease:

1. Burning or difficulty during urination

2. An increase in the frequency of urination

3. Passage of blood in the urine

4. Puffiness around the eyes, swelling of the hands and feet

5. Pain in the small of the back just below the ribs

6. High blood pressure

Causes and Risk Factors of Kidney Diseases

Unfortunately, the cause of many kidney diseases is still unknown, but controlling high blood pressure and diabetes can reduce the risk of many kidney diseases.

Description of Kidney Diseases

Kidney Function

A major function of the kidneys is to remove waste products and excess fluid from the body. These waste products and excess fluid are removed through urine.

The production of urine involves highly complex steps of excretion and reabsorption. This process is necessary to maintain a stable balance of body chemicals.

The critical regulation of the body's salt, potassium, and acid content is performed by the kidneys. The kidneys also produce hormones and vitamins that affect the function of other organs. For example, a hormone produced by the kidneys stimulates red blood cell production. In addition, other hormones produced by the kidneys help regulate blood pressure and others help control calcium metabolism.

There are two kidneys, each about the size of a fist, located on either side of the spine at the lowest level of the rib cage. Each kidney contains about one million functioning units, called nephrons.

A nephron consists of a filtering unit of tiny blood vessels, called a glomerulus, attached to a tubule. When blood enters the glomerulus, it is filtered and the remaining fluid passes along the tubule. In the tubule, chemicals and water are either added to or removed from this filtered fluid, according to the body's needs, with the final product being the urine we excrete.

Types Of Kidney Disease

Kidney disease usually affects both kidneys. If the kidneys' ability to remove and regulate water and chemicals is seriously damaged by disease, waste products and excess fluid build up occur, causing severe swelling and symptoms of uremia (kidney failure).

There are many different types and causes of kidney disease. These can be characterized as hereditary, congenital or acquired.

Hereditary Disorders

These can be transmitted to both males and females, and generally produce clinical symptoms from teenage years to adulthood. The most prevalent hereditary kidney condition is polycystic kidney disease. Other hereditary conditions include Alport's syndrome, hereditary nephritis, primary hyperoxaluria and cystinuria.

Congenital Disease

This usually involves some malformation of the genitourinary tract, usually leading to some type of obstruction which subsequently produces infection and/or destruction of kidney tissue. The destruction can eventually progress to chronic kidney failure.

Acquired Kidney Disease

These diseases are numerous, the general term being nephritis (meaning inflammation of the kidney). The most common type of nephritis is glomerulonephritis, and again, this has many causes.

Kidney Stones

These are very common, and when they pass, the pain can be extremely severe in the side and back. Stone formation can be an inherited disorder, secondary to a malformation and/or infection in the kidney, or can occur without any prior problem. The pain can appear suddenly and in waves, and then disappear rapidly when the stone is passed.

Nephrotic Syndrome

This refers to a large protein loss in the urine [frequently in association with low blood protein (albumin) levels, an elevated blood cholesterol and severe retention of body fluid, causing swelling (edema)]. This disease can be a primary disorder of the kidney or secondary to an illness, affecting many parts of the body (for example diabetes mellitus).

Long-standing High Blood Pressure (hypertension)

This can cause kidney disease itself or can be a result of a kidney disorder. Uncontrolled high blood pressure can accelerate the natural course of any underlying kidney disease.

Diabetes

Long standing diabetes can lead to kidney failure. However, tight control of blood glucose levels over the years may reduce those complications.

Drugs and Toxins

Certain medications, toxins, pesticides and "street" drugs (i.e., heroin) can also produce kidney damage.

Definition of Kidney Diseases

Kidney diseases are disorders that affect the kidneys; the two organs that remove waste products, produce certain hormones, and regulate the level of chemicals in blood.