Chronic kidney failure occurs when disease or dis- order damages the kidneys so that they can no longer adequately remove fluids and wastes from the body or maintain proper levels of kidney-regulated chemicals in the bloodstream.
Description
Chronic kidney failure, also known as chronic renal failure, affects over 250,000 Americans annually. It may be caused by a number of diseases and inherited disorders, but the progression (end result) of chronic kidney failure is always the same. The kidneys, which serve as the body's natural filtration system, gradually lose their ability to remove fluids and waste products (urea) from the bloodstream. They also fail to regulate certain chemicals in the bloodstream and allow protein to leak into the urine. Chronic kidney failure is irreversible and eventually leads to total kidney failure, known as end-stage renal disease (ESRD). Without treatment and intervention to remove wastes and fluids from the bloodstream, ESRD is inevitably fatal.
Causes and symptoms
Kidney failure is caused by acquired disease or hereditary disorders in the kidneys. The four most common causes of chronic kidney failure include:
Diabetes. Diabetes mellitus (DM), both insulin dependant (IDDM) and non-insulin dependant (NIDDM), occurs when the body cannot produce and/or use insulin, the hormone necessary for the body to process glucose. Long-term diabetes may cause the glomeruli, the filtering units located in the nephrons of the kidneys, to gradually lose function.
Hypertension. High blood pressure is both a cause and a result of kidney failure. The kidneys can become stressed and ultimately sustain permanent damage from blood pushing through them at excessive pressures over long periods of time.
Glomerulonephritis. Glomerulonephritis is an inflammation of the glomeruli, or filtering units of the kidney. Certain types of glomerulonephritis are treatable, and may only cause a temporary disruption of kidney functioning.
Polycystic kidney disease. Polycystic kidney disease is an inherited disorder that causes cysts to form in the kidneys. These cysts impair the regular functioning of the kidney.
Initially, symptoms of chronic kidney failure develop slowly. Even individuals with mild to moderate kidney failure may have few symptoms in spite of increased urea in their blood. Among signs and symptoms that may be present at this point are frequent urination during the night and high blood pressure.
Most symptoms of chronic kidney failure are not apparent until kidney disease has progressed significant- ly. Common symptoms include:
Anemia. The kidneys are responsible for the production of erythropoietin (EPO), a hormone that stimulates red cell production. If kidney disease causes shrinking of the kidney, this red cell production is hampered.
Bad breath or a bad taste in mouth. Urea in the saliva may cause an ammonia-like taste in the mouth.
Bone and joint problems. The kidneys produce vitamin D, which aids in the absorption of calcium and keeps bones strong. In patients with kidney failure, bones may become brittle, and in children, normal growth may be stunted. Joint pain may also occur as a result of unchecked phosphate levels in the blood.
Edema. Puffiness or swelling around the eyes and legs.
Frequent urination.
Foamy or bloody urine. Protein in the urine may cause it to foam significantly. Blood in the urine may indicate bleeding from diseased or obstructed kidneys, bladder, or ureters.
Headaches. High blood pressure may trigger headaches.
Hypertension, or high blood pressure. The retention of fluids and sodium causes blood volume to increase, which, in turn, causes blood pressure to rise.
Increased fatigue. Toxic substances in the blood and the presence of anemia may cause feelings of exhaustion.
Itching. Phosphorus, which is typically eliminated in the urine, accumulates in the blood of patients with kidney failure. This heightened phosphorus level may cause itching of the skin.
Low back pain. Pain where the kidneys are located, in the small of the back below the ribs.
Nausea, loss of appetite, and vomiting. Urea in the gastric juices may cause upset stomach. This can lead to malnutrition and weight loss.
Diagnosis
Kidney failure is typically diagnosed and treated by a nephrologist, a physician specializing in kidney dis- ease. The patient suspected of having chronic kidney failure will undergo an extensive blood work-up, usually performed by a laboratory technologist or technician. Blood tests will assess the levels of creatinine, blood urea nitrogen (BUN), uric acid, phosphate, sodium, and potassium in the blood. Urine samples will also be collected, usually over a 24-hour period, to assess protein loss.
Uncovering the cause of kidney failure is critical to proper treatment. A full assessment of the kidneys is necessary to determine if the underlying disease is treatable and if the kidney failure is chronic or acute. X ray, MRI, computed tomography scan, ultrasound, renal biopsy, and/or arteriogram of the kidneys may be employed to determine the cause of kidney failure and level of remaining kidney function. X rays and ultrasound of the bladder and/or ureters may also be taken. Most imaging studies are performed by radiology technicians.
Treatment
Chronic kidney failure is an irreversible condition. Hemodialysis, peritoneal dialysis, or kidney transplantation must be employed to replace the lost function of the kidneys if the failure progresses to ESRD. In addition, dietary changes and treatment to relieve specific symptoms such as anemia and high blood pressure are critical to the treatment process.
Hemodialysis
Hemodialysis is the most frequently prescribed type of dialysis treatment in the United States. Most hemodialysis patients require treatment three times a week, for an average of three to four hours per dialysis "run" depending on the type of dialyzer used and their current physical condition. The treatment involves circulating the patient's blood outside of the body through an extracorporeal circuit (ECC), or dialysis circuit. The dialysis circuit consists of plastic blood tubing, a two-compartment filter known as a dialyzer, or artificial kidney, and a dialysis machine that monitors and maintains blood flow and administers dialysate, a chemical bath used to draw waste products out of the blood. The patient's blood leaves and enters the body through two needles inserted into the patient's vein, called an access site, and is pushed through the blood compartment of the dialyzer. Once the patient's blood is inside the dialyzer, excess fluids and toxins are pulled out of the bloodstream and into the dialysate compartment, where they are carried out of the body. At the same time, electrolytes and other chemicals in the dialysate solution move from the dialysate into the bloodstream. The purified, chemically balanced blood is then returned to the body. Specially trained nurses and dialysis technicians supervise and monitor patients during treatment.
Peritoneal dialysis
In peritoneal dialysis (PD), the peritoneum, (lining of the abdomen) acts as a blood filter. A catheter is surgically inserted into the patient's abdomen. During treatment, the catheter is used to fill the abdominal cavity with liquid dialysate. Waste products and excess fluids move from the patient's bloodstream into the dialysate solution. After a waiting period of 6 to 24 hours, depending on the treatment method used, the waste-filled dialysate is drained from the abdomen, and replaced with clean dialysate. There are three types of peritoneal dialysis, which vary by treatment time and administration method: continuous ambulatory peritoneal dialysis (CAPD), continuous cyclic peritoneal dialysis (CCPD), and intermittent peritoneal dialysis (IPD).
Kidney transplantation
Kidney transplantation involves surgically implanting a functioning kidney, known as a graft, from a brain dead organ donor (a cadaver transplant), or from a living donor, to a patient with ESRD. Patients with chronic renal disease who need a transplant and do not have a living donor register with UNOS (United Network for Organ Sharing), the federal organ procurement agency. UNOS places patients on a waiting list for a cadaver kidney transplant. Kidney availability is based on the patient's health status. When the new kidney is transplanted, the patient's diseased kidneys may or may not be removed, depending on the circumstances surrounding the kidney failure. A regimen of immunosuppressive (anti-rejection) medication is required after transplantation surgery.
Dietary management
A diet low in sodium, potassium, and phosphorous, three substances that healthy kidneys excrete, is critical in managing kidney disease. Other dietary restrictions, such as a reduction in protein, may be prescribed depending on the cause of kidney failure and the type of dialysis treatment employed. Patients with chronic kidney failure also need to limit their fluid intake. Patients may receive instruction about appropriate dietary measures from registered dietitians, nutritionists, nurses, or health educators.
Medications and dietary supplements
Kidney failure patients with hypertension typically take medication to control their high blood pressure. Epoetin alfa, or EPO (Epogen), a hormone therapy, and intravenous or oral iron supplements are used to manage anemia, especially if the kidneys have been surgically removed. A multivitamin may be prescribed to replace vitamins lost during dialysis treatments. Vitamin D, which promotes the absorption of calcium, along with calcium supplements, may also be prescribed.
Since 1973, Medicare has reimbursed up to 80% of ESRD treatment costs, including the costs of dialysis and transplantation as well as the costs of some medications. To qualify for benefits, a patient must be insured or eligible for benefits under Social Security, or be a spouse or child of an eligible American. Private insurance and state Medicaid programs often cover the remaining 20% of treatment costs.
Prognosis
Early diagnosis and treatment of kidney failure is critical to improving length and quality of life in chronic kidney failure patients. Patient outcome varies; it depends on the cause of chronic kidney failure and the method chosen to treat it. Overall, patients with chronic kidney disease leading to ESRD have a shortened life span. According to the United States Renal Data System (USRDS), the life span of an ESRD patient is 18-47% of the life span of the age-sex-race matched general population. ESRD patients on dialysis have a life span that is 16-37% of the general population.
The demand for kidneys to transplant continues to exceed supply. Cadaver kidney transplants have a 50% chance of functioning nine years, and living donor kidneys that are well-matched (have two matching antigen pairs) have a 50% chance of functioning for 24 years. However, some transplant grafts have functioned for more than 30 years.
Health care team roles
Patients with chronic kidney failure are treated by a team that includes nephrologists, dialysis technicians, nurses, radiology technicians, and laboratory technicians. Patients undergoing kidney transplant are cared for by a transplant team headed by a transplant surgeon. Registered dietitians, nutritionists, and nurses instruct patients about dietary changes to manage their disease.
KEY TERMS
End-stage renal disease (ESRD)—Total kidney failure; chronic kidney failure is diagnosed as ESRD when kidney function falls to 5-10% of capacity.
Nephrotic syndrome—Characterized by protein loss in the urine, low protein levels in the blood, and fluid retention.
Ureters—The two ducts that pass urine from each kidney to the bladder.
BOOKS
Brenner, Barry M. and Floyd C. Rector, Jr., eds. The Kidney, 5th edition. Philadelphia: W.B. Saunders Company, 1996.
Cameron, J. S. Kidney Failure: The Facts. New York: Oxford Univ. Press, 1996.
Ross, Linda M., ed. Kidney and Urinary Tract Diseases and Disorders Sourcebook. Vol. 21. Health Reference Series. Detroit: Omnigraphics, 1997.
U.S. Renal Data System. USRDS 1997 Annual Data Report. Bethesda, MD: The National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases, 1996. (Available in paper and microfiche versions from National Technical Information Service (NTIS), Springfield, VA.)
The Washington Manual of Medical Therapeutics, 30th Edition. Philadelphia PA: Lippincott Williams & Wilkins, 2001, pp. 267-270.
PERIODICALS
Friedman, Elia A. "End-stage Renal Disease Therapy: An American Success Story." Journal of the American Medical Association 275 (April 1996): 1118-22.
Taylor, Judy H. "End-stage Renal Disease in Children: Diagnosis, Management, and Interventions." Pediatric Nursing 22 (Nov-Dec 1996): 481-92.
ORGANIZATIONS
American Association of Kidney Patients (AAKP). 100 S. Ashley Drive, Suite 280, Tampa, FL 33602. (800)749-2257. <http://www.aakp.org>.
American Kidney Fund (AKF). Suite 1010, 6110 Executive Boulevard, Rockville, MD 20852. (800)638-8299. <http://www.arbon.com/kidney/>.
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Natcher Building - 6AS-13K, 45 Center Drive, Bethesda, MD 20892-6600. <http://www.niddk.nih.gov.>.
National Kidney Foundation (NKF). 30 East 33rd Street, New York, NY 10016. (800)622-9020. <http://www.kidney.org>.
United States Renal Data System (USRDS). USRDS Coordinating Center, 315 W. Huron, Suite 240, Ann Arbor, MI 48103. (313)998-6611. <http://www.med.umich.edu/usrds/>.
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