Chronic kidney failure

Definition

Chronic kidney failure occurs when disease or disorder damages the kidneys so that they are no longer capable of adequately removing fluids and wastes from the body or of maintaining the proper level of certain kidney-regulated chemicals in the bloodstream.

Description

Chronic kidney failure, also known as chronic renal failure, affects approximately 26 million Americans annually with over 20 million at increased risk of developing the disease. It is caused by a number of diseases and inherited disorders, but the progression 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 deposit protein into the urine. Chronic kidney failure is irreversible, and will eventually lead to total kidney failure, also known as end-stage renal disease (ESRD). Without proper treatment intervention to remove wastes and fluids from the bloodstream, ESRD is fatal.

Causes and symptoms

Kidney failure is triggered by disease or a hereditary disorder in the kidneys. Both kidneys are typically affected. The two most common causes of chronic kidney failure include:

• Diabetes. This condition occurs when the body does not produce and/or use insulin, the hormone necessary to convert starches, sugar, and other food into energy. The two forms of diabetes are categorized as Type 1 or Type 2. Type 1 diabetes occurs when the body fails to produce insulin. This in turn results in the body's inability to process glucose. Approximately 5–10% of Americans have type 1 diabetes. Type 2 diabetes involves a combination of insulin resistance, whereby the body fails to use insulin appropriately, and insulin deficiency. The majority of Americans diagnosed with diabetes have type 2 diabetes.
• Hypertension. High blood pressure is unique in that it is both a cause and a major symptom of kidney failure. The kidneys can become stressed and ultimately sustain permanent damage from blood pushing through them at an excessive level of pressure over a long period of time.

Other possible causes of chronic kidney failure include:

• Amyloidosis. A rare, and in some instances fatal disease that occurs when amyloid proteins build up in the organs. Amyloidosis can affect the heart, kidneys, spleen, liver, gastrointestinal tract, and nervous system.
• Glomerulonephritis. Glomerulonephritis is a chronic 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.
• Kidney artery stenosis. This condition occurs when the kidney artery becomes blocked. In older adults, artery blockage is usually caused by fatty deposit build up, a condition called atherosclerosis.
• Kidney cancer.
• Obstructive nephropathy. This condition occurs when the outflow of urine is obstructed by an enlarged prostate, kidney stones or tumors, or by a condition called vesicoureteral reflux; when urine from the bladder flows into the kidneys. The pressure in the kidneys results in diminished function.
• Polycystic kidney disease. Polycystic kidney disease is an inherited disorder that causes cysts to be formed on the nephrons, or functioning units, of the kidneys. The cysts hamper the regular functioning of the kidney.
• Sickle cell anemia.
• Systemic lupus erythematosus. A chronic inflammatory disease that affects many parts of the body, particularly the kidneys.

Initially, symptoms of chronic kidney failure develop slowly. Even individuals with mild to moderate kidney failure may show few symtpoms in spite of increased urea in their blood. Among the 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 significantly. Common symptoms include:

• Anemia. The kidneys are responsible for the production of erythropoietin (EPO), a hormone which stimulates red cell production. If kidney disease causes shrinking of the kidney, this red blood cell production is hampered.
• Bad breath or a bad taste in mouth. Urea, or waste products, 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. For patients with kidney failure, bones may become brittle, and in the case of 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, arms, hands, and feet.
• 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 wastes 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.
• Lower 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 doctor that specializes in treating the kidneys. The patient that is suspected of having chronic kidney failure will undergo an extensive blood work-up. A blood test 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. An 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.

Treatment

Chronic kidney failure is an irreversible condition. The principal aim of treatment is to arrest or at a minimum delay the progression of the disease. This is accomplished through treatments such as hemodialysis, peritoneal dialysis, or kidney transplantation , all of which replace the lost function of the kidneys. 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 inside of 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.

Peritoneal dialysis

In peritoneal dialysis (PD), the patient's peritoneum, or 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 dialysate. Waste products and excess fluids move from the patient's bloodstream into the dialysate solution. After a waiting period of six 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 attaching a functioning kidney, or 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 don't have a living donor register with UNOS (United Network for Organ Sharing), the federal organ procurement agency, to be placed 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 existing, diseased kidneys may or may not be removed, depending on the circumstances surrounding the kidney failure. A regimen of immunosuppressive, or anti-rejection medication, is required after transplantation surgery.

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. 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 picked up 80% of ESRD treatment costs, including the costs of dialysis and transplantation and 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.

Nutrition/Dietetic concerns

A diet low in sodium, potassium, and phosphorous, three substances that the kidneys regulate, 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.

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 by 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 lifespan. According to the United States Renal Data System (USRDS), the lifespan of an ESRD patient is 18–47% of the lifespan of the age-sex-race matched general population. ESRD patients on dialysis have a lifespan that is 16–37% of the general population.

The demand for kidneys to transplant continues to exceed supply. In 2007, approximately 28,000 kidney transplants were performed in the United States. This is a modest number considering that more than 98,000 patients were on the UNOS waiting list as of the first quarter of 2008.

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.

Combined medical advances in organ preservation, surgical procedure, and the development of more effective drugs to inhibit rejection have improved the success rates of all types of organ and tissue transplants. Studies conducted in 2007 indicate that transplantation from a living donor had a 95% survival rate after one year as compared to a 90% survival rate for deceased donor transplants. In addition, according to the Organ Procurement and Transplantation Network, patients who received living-donor transplants demonstrate an 80% survival rate after five years and those who received a deceased donor transplant have a 70% survival rate.

Resources

PERIODICALS

Wu, Christine MD, and Ron Shapiro MD, Henkie Tan MD, PhD, Amit Basu MD, Cynthia Smetanka MD, Claire Morgan MD, Nirav Shah MD, Jerry McCauley MD, MPH, Mark Unruh MD, MSc. “Kidney Transplantation in Elderly People: The Influence of Recipient Comorbidity and Living Kidney Donors.” Journal of the American Geriatrics Society 56, no. 2 (2008): 231–238.

ORGANIZATIONS

American Association of Kidney Patients, 100 S. Ashley Drive, #280, Tampa, FL, 33602, (800) 749-2257, http://www.aakp.org.

American Diabetes Association, 1701 North Beauregard St., Alexandria, VA, 22311, (800) 342-2383, http://www.diabetes.org.

American Kidney Fund (AKF), Ste. 1010, 6110 Executive Blvd., Rockville, MD, 20852, (800) 638-8299, http://www.arbon.com/kidney.

National Kidney Foundation, 30 East 33rd St., New York, NY, 10016, (800) 622-9010, http://www.kidney.org.

United Network for Organ Sharing, 700 North 4th St., Richmond, VA, 23219, (888) 894-6361, http://www.unos.org.

United States Renal Data System (USRDS), TheUniversity of Michigan, 315 W. Huron, Ste. 240, Ann Arbor, MI, 48103, (734) 998-6611, http://www.med.umich.edu/usrds.

Lisa M. Piazza M.A.