In kidney failure, the kidneys lose their ability to filter enough waste products from the blood and to regulate the body's balance of salt and water. Eventually, the kidneys slow their production of urine, or stop producing it completely. Waste products and water accumulate in the body. This can lead to potentially life-threatening complications. Excess fluid can accumulate in the lungs and extreme changes in blood chemistry can affect the function of the heart and brain. There are three general categories of kidney failure (also called renal failure). They are:
Symptoms vary depending on the type of renal failure.
Acute renal failure - Symptoms include:
Decreased urine output
Swelling (edema) resulting from salt and water overload
High blood pressure
Lethargy caused by the toxic effects of waste products on brain function
If left untreated, acute renal failure can cause extra fluid to back up behind the heart into the lungs, cardiac rhythm abnormalities, behavioral changes, seizures and coma.
Chronic kidney disease and end-stage renal failure- Because the kidney damage in chronic renal failure occurs slowly over a long time, symptoms develop slowly, usually beginning when more than 80% of kidney function is lost. When this occurs, symptoms can include:
High blood pressure
Slowing of growth in children
Bone damage in adults
If you have an illness or medical condition that increases the risk of acute renal failure, your doctor will watch for symptoms and signs of kidney failure. He or she may give you blood and urine tests and measure the amount of urine you produce. If you have a chronic (long-term) medical condition that increases the risk of long-term kidney damage, your doctor will check your blood pressure and look for symptoms and signs of chronic renal failure during regularly scheduled office visits.
To confirm the diagnosis of acute renal failure, your doctor will order tests of your urine and blood tests to check for chemical abnormalities. Levels of these chemicals are elevated in people with poor kidney function. Other tests may include:
A chest X-ray to check for signs of excess fluid in the lungs
X-rays of the abdomen or an ultrasound examination of the kidneys to check for a urinary tract obstruction
A kidney biopsy, in which a sample of kidney tissue is removed and examined in a laboratory
If you have symptoms or a chronic medical condition that is known to potentially cause kidney failure, your doctor will periodically order blood tests to check on kidney function. Because chronic renal failure typically develops gradually, a physical examination may be normal. To confirm the diagnosis of chronic renal failure, the same evaluation may be recommended as for acute renal failure, including tests of blood and urine, ultrasound of kidneys and in some cases, a kidney biopsy.
Doctors diagnose end-stage renal disease when symptoms become pronounced and certain blood chemicals reach very high levels in the blood, indicating that kidney function has been severely affected.
Acute renal failure may go away within a few days simply by stopping a medication or reversing whatever caused the situation. Exactly how long the illness lasts varies considerably from person to person, depending on the cause of the kidney problem. In rare cases, acute renal failure progresses to end-stage renal disease.
Chronic renal failure is a lifelong problem that can worsen over time to become end-stage renal disease. End-stage renal disease is a permanent condition that can be treated only with dialysis or a kidney transplant.
Many forms of kidney failure cannot be prevented. People who have diabetes, high blood pressure or coronary artery disease should try to control the illness with appropriate diet, medication and lifestyle changes. Before a computed tomography (CT) scan or angiogram procedure that uses contrast dye, your doctor will want to be sure that your kidneys can handle the dye load. Also your doctor will want you to be well hydrated with either oral or intravenous fluids.
If you already have chronic kidney failure, treating medical problems such as diabetes and high blood pressure and avoiding medications and other treatments that can further damage the kidneys may prevent worsening of kidney function. If you have chronic kidney failure, you should tell any physician who treats you.
Treatment depends on the type of kidney failure.
Acute renal failure - Treatment begins with measures to correct the cause of renal failure (shock, hemorrhage, burns, heart attack, etc.). Usually doctors order intravenous fluids to be sure that there is sufficient blood flow to the kidneys. This is not done if there is already severe fluid overload. Medications may be needed to lower high levels of potassium and other blood chemicals. If severe fluid overload or abnormalities in blood chemistry cannot be corrected with medications, emergency short-term dialysis may be necessary.
Chronic renal failure - People with chronic renal failure are monitored closely with frequent physical examinations, blood pressure checks and blood testing. Treatment often includes:
A low-protein and low-salt diet
Medications to adjust blood chemical levels
Medications to treat high blood pressure
A hormonal medication called erythropoietin (Epogen, Procrit) to correct anemia (a low level of red blood cells).
End-stage renal disease - End-stage renal disease is treated with dialysis. Dialysis must continue indefinitely, or until a suitable donor can be found for a kidney transplant. Dialysis mechanically removes waste products from the blood. In rare cases, patients with severe high blood pressure or chronic pyelonephritis may need both kidneys removed surgically before a transplant.
Many people with acute renal failure already are hospitalized for their other medical conditions when kidney failure develops. Other people should call a health care professional whenever the amount of urine they produce either increases or decreases markedly. In people with decreased urine output, swelling of the face and ankles is another danger sign, especially if there is also shortness of breath. For people with chronic renal failure, it is a good idea to check with your health care professional whenever a new medication is prescribed.
Most children with acute renal failure have a good outlook for recovering their kidney function, although in rare cases, end-stage renal disease can develop. Among adults, the chances of recovery depend primarily on the underlying reason for acute renal failure rather than the renal failure itself.
People with chronic renal failure may have a continuing decrease in kidney function, but not everyone develops end-stage renal disease. For those who do, the time it takes for end-stage renal disease to develop varies from person to person.
National Institute of Diabetes and Digestive and Kidney Disorders
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Building 31, Room 9A04
Center Drive, MSC 2560
Bethesda, MD 20892-2560
National Kidney Foundation
30 East 33rd St.
New York, NY 10016