Chronic kidney failure usually results from a gradual loss of kidney function. Occasionally it follows rapid loss of kidney function. Few symptoms develop until after more than 75% of the kidney's function is lost.

Without treatment, unfiltered toxins in the blood damage all the person's major organs. If he or she can tolerate it, the person with chronic kidney failure will receive dialysis or a kidney transplant.

What causes it?

Chronic kidney failure can follow a long list of diseases described in other parts of this chapter:

chronic kidney tissue disease, such as glomerulonephritis

chronic infections, such as pyelonephritis

inherited defects, such as cyst-filled kidneys

vascular diseases, such as nephrosclerosis or high blood pressure

obstructions, such as kidney stones

connective-tissue diseases, such as lupus

drugs that affect the kidneys, such as long-term aminoglycoside therapy

endocrine diseases, such as complications of diabetes.

All of these factors gradually destroy the kidney's tissue and cause the organ to fail. If the person has acute kidney failure that does not respond to treatment, chronic kidney failure develops.

What are its symptoms?

Chronic kidney failure produces major changes in all of the person's body systems:

Kidney and urinary system: Initial changes include low blood pressure, dry mouth, loss of skin tone, listlessness, fatigue, and nausea; later, confusion. As the kidney loses its capacity to excrete sodium, the person suffers sodium retention and overload, with muscle irritation then weakness. The person's urine output decreases, and the urine's chemical composition is altered .

Heart and circulation: Kidney failure leads to high blood pressure, irregular heartbeat (including life-threatening fast heartbeat or fibrillation), swelling, and congestive heart failure.

Respiratory: Lung changes include susceptibility to infection, accumulation of fluid, pain, pneumonia, and difficult breathing due to congestive heart failure.

Gastrointestinal tract: Inflammation and ulceration affect many parts of this system. Obvious symptoms include a metallic taste in the mouth, ammonia on the breath, poor appetite, nausea, and vomiting.

Skin: Typically, the person's skin is pale, yellowish bronze, dry, and scaly. Fingernails may be thin and brittle with lines, and hair may be dry and brittle, change color, and fallout easily.

Nervous system: Restless leg syndrome, one of the first signs of nerve damage, causes pain, burning, and itching in the legs and feet. It may be relieved by voluntarily shaking or rocking them. The person also may experience muscle cramping and twitching, shortened memory and attention span, apathy, drowsiness, irritability, confusion, coma, and seizures. The doctor may check for brain wave changes indicating damage.

Endocrine: Chronic kidney failure can cause stunted growth patterns in children, infertility and reduced sexual drive in both sexes, reduced or stopped menstruation, impotence and decreased sperm production, and increased blood glucose levels similar to diabetes.

Blood changes: These include anemia, decreased red blood cell survival time, blood loss from dialysis and gastrointestinal bleeding, and mild clotting problems that can get worse.

Skeletal: Mineral and hormone imbalances cause muscle and bone pain, bone loss, fractures, and calcium deposits in the brain, eyes, gums, joints, heart lining, and blood vessels. Arterial calcification may produce coronary artery disease. In a child, kidney-related rickets may develop.

How is it diagnosed?

The doctor will ask about symptoms of worsening kidney function and order a lab test called the creatinine clearance test to assess kidney function. Then, the doctor will order a variety of lab tests to pinpoint the specific problems. Blood and urine samples, X-ray studies, and kidney biopsy may be used to determine the source of the problem.

How is it treated?

The doctor may use dietary therapy to correct the person's specific symptoms. A low-protein diet reduces the production of materials that the kidneys can't excrete. (However, a person receiving continuous peritoneal dialysis will be given a high-protein diet.) A high-calorie diet prevents mineral imbalances that cause tissue damage. The prescribed diet also restricts sodium and potassium.

The doctor may work to correct the person's fluid balance with fluid restriction and drugs that control blood pressure, swelling, nausea and vomiting, stomach irritation or constipation, and itching skin. The person may benefit from supplementary vitamins, especially B, D, and essential amino acids.

If the person's gastrointestinal tract is affected, he or she may need regular stool analysis to detect blood and cleansing enemas to remove the blood. Anemia calls for iron and folate supplements, and severe anemia may require transfusions, though they provide only temporary help. The person may be given hormone therapy to increase red blood cell production.

The person with chronic kidney failure in its severe stage may be given either hemodialysis or peritoneal dialysis to help control most of the symptoms. But anemia, nerve damage, and other complications may persist. Finally, maintenance dialysis itself can produce complications. A kidney transplant may be needed for someone with end-stage kidney disease.