What is kidney failure?

Your kidneys are two bean-shaped organs, each about the size of your fist, located at the back of your upper abdomen on either side of your spine. The kidneys' main function is to eliminate excess fluid and waste material from your blood. When your kidneys lose this filtering ability, dangerous levels of fluid and waste accumulate in your body — a condition known as kidney (renal) failure.

Sometimes kidney failure occurs suddenly (acute kidney failure). This is most likely to happen after complicated surgery or severe injuries, or when blood vessels leading to the kidneys become blocked.

Chronic renal failure, on the other hand, usually develops slowly, with few symptoms in the early stages. Many people with chronic renal failure don't have symptoms until their kidney function has decreased to less than 25 percent of normal. High blood pressure and diabetes — a disorder that causes high blood sugar levels — are the most common causes.

In end-stage renal disease, the kidneys function at less than 10 percent of normal capacity. At this point they're simply not able to sustain life. People with end-stage renal disease need either dialysis or a kidney transplant to stay alive. When a transplant isn't possible — often because of poor general health — dialysis becomes the only option. More than 300,000 Americans receive long-term dialysis therapy, and about 80,000 live with a functioning kidney transplant.

Signs and symptoms

The signs and symptoms of kidney failure vary, depending on whether the failure is acute or chronic.

Acute kidney failure
Acute kidney failure occurs when the kidneys suddenly stop filtering waste products from your blood. The signs and symptoms may include:

• Fluid retention
  
  
• Bleeding, often in the stomach or intestines
  
  
• Confusion
  
  
• Seizures
  
  
• Coma

Chronic kidney failure
According to the National Kidney Foundation, almost 20 million adult Americans have chronic kidney disease and another 20 million are at risk of developing it. Over time, chronic kidney failure can lead to congestive heart failure, weak bones, stomach ulcers and damage to the central nervous system. Unfortunately, signs and symptoms often don't appear until irreversible damage has occurred. They include:

• Abnormal urine tests
  
  
• High blood pressure
  
  
• Unexplained weight loss
  
  
• Anemia
  
  
• Nausea or vomiting
  
  
• Malaise or fatigue
  
  
• Headaches that seem unrelated to any other cause
  
  
• Decreased urine output
  
  
• Decreased mental sharpness
  
  
• Muscle twitches and cramps
  
  
• Bleeding in the intestinal tract
  
  
• Yellowish-brown cast to the skin
  
  
• Unusual itching
  
  
• Sleep disorders

End-stage renal disease
For some people, end-stage renal disease is the final result of chronic kidney failure. At this point, kidney function is so poor that either dialysis or kidney transplantation is needed to sustain life. A number of complications may develop with end-stage renal disease, depending on how rapidly it occurs, including:

• Anemia
  
  
• High blood pressure
  
  
• Congestive heart failure
  
  
• Bone disease
  
  
• Digestive tract problems
  
  
• Loss of mental functioning (dementia)

Congestive heart failure Osteoporosis Anemia High blood pressure High Blood Pressure Center

Causes

Your kidneys are part of a complex system that removes excess fluid and waste material from your blood. Initially, blood enters your kidneys through the renal arteries, which are branches of the aorta — the main artery leading from your heart. From there, blood moves through structures in your kidneys known as nephrons.

• Continuous ambulatory peritoneal dialysis (CAPD). You perform this type of dialysis yourself at home, exchanging the dialysis solution in your abdomen four times a day, 7 days a week. These exchanges are spaced throughout the day.
  
  
• Continuous cycling peritoneal dialysis (CCPD). In this type of dialysis, a machine (cycler machine) automatically infuses dialysis solution into and out of your peritoneal cavity over a period of 10 to 12 hours while you sleep.

If you have no other serious medical conditions, a kidney transplant is usually a better option than dialysis because it provides a healthier and better quality of life. But you may need dialysis until a suitable kidney donor is found. Finding the right donor may be difficult, however.

The more compatible the donor is with your blood type, cell surface proteins, and antibodies, the less likely your body is to reject the new kidney. A sibling is likely to be the best donor. But you may not have siblings, or they may not qualify for various reasons. In that case, another blood relative, such as a parent, aunt, uncle or cousin, or even a non-blood-related adult may be considered. When a living donor isn't available, tissue-typing centers throughout the country may search for a kidney from an accident victim or other person who has offered to donate organs after his or her death.

Kidney donation Organ transplantation: Coping with waiting

Prevention

It's often not possible to prevent kidney failure. But you may reduce your risk by following these suggestions:

• Don't abuse alcohol or other drugs, including over-the-counter pain medications such as aspirin, acetaminophen and ibuprofen. Avoid long-term exposure to heavy metals, such as lead, as well as to solvents, fuels and other toxic substances.
  
  
• If you have a chronic medical condition that increases your risk of kidney failure, carefully follow all your doctor's recommendations for managing your condition. The American Diabetes Association recommends albumin-specific urine tests every year for most people with diabetes.
  
  
• If you have chronic kidney failure and are thinking of becoming pregnant, consider a pre-pregnancy consultation with a knowledgeable obstetrician or nephrologist to discuss your risks. If you're already pregnant, be sure to get comprehensive medical care — including prenatal visits every 2 weeks for at least the first 32 weeks.

Self-care

If you have end-stage renal disease, your doctor may ask you to limit the amount of fluids you consume every day. In most cases, limiting fluids means more than reducing the amount of water you drink. It may include cutting back on your consumption of such things as ice cubes and ice chips, coffee and tea, sodas, fruit and vegetable juices, soups, milk, cream, ice cream, sherbets, sorbets, Popsicles and even gelatin.

When you limit liquids, you may have a hard time controlling your thirst. The following suggestions may help you feel less thirsty:

• Suck on a lemon wedge or a few ice chips.
  
  
• Rinse your mouth with water but don't swallow it.
  
  
• Eat a piece or two of sour candy or chew gum to increase the moisture level in your mouth.

— June 14, 2002 —