Dialysis is a procedure to cleanse the blood of wastes, excess fluid and salt after the kidneys can no longer perform these functions. It is the most common treatment for end-stage renal disease (ESRD). The only alternative to dialysis after chronic kidney failure is a kidney transplant.

There are two main types of dialysis:

• Hemodialysis uses a tube to draw blood from the body into a machine that filters out wastes and excess fluid. The machine then returns the cleansed blood to the body. Hemodialysis is usually performed three times a week for several hours at each session. It is most often done at a clinic called a dialysis center, but some patients can be trained to complete hemodialysis at home.
  
  
• Peritoneal dialysis (PD) uses the body’s own abdominal membrane (peritoneum) as the filter. First, a surgeon surgically implants a permanent tube in the abdomen. Dialysis solution is poured through the tube and fills the space between the abdominal wall and organs. The solution draws wastes and excess fluid from the bloodstream. After several hours, the used solution is drained from the abdomen. PD is usually performed in several consecutive sessions daily at home or work.

People with risk factors for renal failure, such as diabetes or high blood pressure, should have their blood and urine tested regularly to catch and treat kidney disease in its early stages and avoid the need for dialysis or transplant.

Dialysis does not cure chronic kidney disease and usually continues for life unless a transplant is possible. Dialysis is also used at hospitals to treat some cases of acute kidney failure due to causes such as poisoning or heart attack. Sometimes dialysis resolves acute kidney failure and is needed only temporarily.

Dialysis is the passage of a solution through a membrane. Usually this term is used to refer to renal dialysis, a procedure that removes toxins, excess fluid and salt from the blood when the kidneys can no longer perform these functions.

Kidney dialysis becomes necessary when the buildup of wastes begins to make a person ill, typically when renal function falls below 10 percent in someone with chronic kidney failure (end-stage renal disease, ESRD). Causes of chronic kidney failure include diabetes, high blood pressure, lupus, prolonged obstructions in the urinary tract, and kidney disorders such as polycystic kidney disease and some types of nephritis.

Chronic kidney failure is irreversible, and dialysis does not cure it. Treatment usually continues for life unless a kidney transplant is available, and patients may die within weeks if they discontinue dialysis. However, there have been unusual cases where kidney function improved enough that a physician could safely discontinue dialysis.

Dialysis also can be used to treat acute kidney failure, which is sometimes reversible. Causes of this sudden condition include trauma, blood loss, shock, poisoning (sometimes caused by medications such as common painkillers), heart attack, severe infections such as E. coli bacteria, dehydration, glomerulonephritis, and recent obstructions in the urinary tract due to causes such as kidney stones or prostate enlargement. Dialysis can resolve some cases of acute kidney failure and be needed only temporarily.

The kidneys are central to the body’s waste-removal system. They are composed of filtering units called nephrons, which themselves are made up of tiny blood vessels called glomeruli. Waste products in the blood pass through the glomeruli and later leave the body in urine. Protein and other needed substances are normally too big to leak through the filters.

The primary cause of kidney failure in the United States is diabetic kidney disease (diabetic nephropathy). Diabetes damages the kidneys by making them filter too much blood. After years of overwork, the glomeruli begin leaking small amounts of protein in the urine (microalbuminuria). If the condition is not caught early, it will worsen to proteinuria, the presence of larger amounts of protein in the urine. High blood pressure, often associated with diabetes, speeds up the damage. This damage can lead to chronic kidney failure and the need for dialysis or a kidney transplant.

People with diabetes can avoid or delay the need for dialysis by having their physician perform a special urine test for microalbuminuria annually upon diagnosis of type 2 diabetes or starting five years after diagnosis of type 1 diabetes. A physician may also recommend other assessments of kidney function, such as glomerular filtration rate (GFR) and waste product testing.

Dialysis patients, especially those with diabetes, may have relatives with undiagnosed kidney disease, researchers have determined. At-risk family members may also benefit from testing for microalbuminuria.

Among diabetes patients in the United States, some racial and ethnic groups are at much higher risk for chronic kidney failure and the need for dialysis, according to the American Diabetes Association:

Treatment usually continues for life, and people with kidney failure may die within weeks if they discontinue dialysis. However, in unusual cases it is possible for kidney function to improve to the point where dialysis can be safely discontinued by a physician.

Dialysis is a life-extending treatment for patients who would otherwise not be able to survive. For some patients, dialysis is not enough to sustain their lives. The U.S. Food and Drug Administration (FDA) has reported an annual mortality rate of up to 23 percent for American dialysis patients. However, some dialysis patients may live as long as people who do not have renal failure, according to the National Kidney Foundation. Researchers are investigating whether dialysis procedures can be improved to reduce that mortality rate. Better patient education also may increase the success of dialysis by encouraging patients to monitor symptoms, adhere to their treatment schedule and undergo regular testing.

Researchers are working on advances in dialysis, including improved home units and a dialysis device that can be worn like a belt.

Preparation for kidney dialysis depends on the type of treatment being used. Hemodialysis can begin with little preparation by using a temporary access site. When time allows, a surgeon prepares a vascular access, the place on the body where blood is siphoned and returned. This surgically prepared site, usually in the forearm, provides a more stable access area for repeated hemodialysis.

The hemodialysis machine is often described as an artificial kidney. However, dialysis cannot replace all of the kidneys’ roles, which in addition to removal of wastes and excess fluid and salt include creation of hormones, activation of vitamin D and balancing of electrolytes.

Individually prescribed dialysis solution pumped around the machine’s filter draws impurities and excess fluids from the blood. Each session is usually performed two to three days a week and lasts three to five hours.

Hemodialysis patients pass the time with activities such as reading, computer work, socializing, napping or light exercise. People often experience fatigue after a session, but the treatment is generally painless except for insertion of needles. Hemodialysis is usually performed at a dialysis center and sometimes at a hospital. In some cases patients can use it at home.

Peritoneal dialysis (PD) requires more preparation. A surgeon inserts a catheter near the navel to allow access to the abdominal (peritoneal) cavity. A few inches of the catheter show outside the abdomen. This catheter remains within the patient, even between treatments. A full schedule of dialysis usually starts after a few weeks to allow healing.

The most popular form of peritoneal dialysis uses gravity to fill and empty the abdomen. A bag of dialysis solution is hung from a pole next to the patient. A tube connects the bag to the catheter in the patient’s abdomen. The solution passes into the abdominal cavity and the patient is disconnected when the bag is empty. The patient is allowed to resume normal activities while the solution remains in the abdominal cavity (dwell time).

After several hours, the patient connects the catheter to an empty bag on the floor. This bag is filled with the used dialysis solution and discarded. Draining and filling takes about half an hour. This exchange procedure is typically completed several times a day and through the night. Some forms of PD use a machine to help fill and empty the abdomen at night during sleep.

The primary advantage of dialysis is the extension of life. People whose kidneys no longer work can die within weeks without dialysis or a kidney transplant.

There are a number of risks common with chronic kidney failure that can occur with either form of dialysis. These conditions occur because the kidneys no longer make hormones or balance the body’s electrolytes and other chemicals. Potential risks of dialysis include:

• Anemia. Insufficient red blood cells result from lack of erythropoietin (EPO), a hormone made by kidneys that stimulates creation of red blood cells. Dialysis patients often receive supplemental EPO because the kidneys no longer form it. Contributors to anemia also include inadequate consumption of vitamins or iron, and blood loss caused by procedures, tests and anticoagulant medications. Some research has found overuse of anemia drugs in dialysis patients. In 2007 the U.S. Food and Drug Administration tightened warning labels on these erythropoiesis-stimulating agents (ESAs) because of potential risks including heart attack and stroke. The agency recommends using the lowest dosage needed to avoid blood transfusions.
  
  
• Weakened bones. Bone disease caused by kidney failure (renal osteodystrophy) affects 90 percent of dialysis patients, according the U.S. National Institutes of Health (NIH). The condition has similarities to osteoporosis. Women and older individuals are at increased risk, and the condition is especially serious in children. Insufficient calcium in the blood (hypocalcemia) can cause the parathyroid glands to release a hormone drawing calcium from the bones and thus weakening them. Excess phosphorus (hyperphosphoremia) can also leach calcium from the bones. Treatments include low-phosphorus diet, medication and exercise.
  
  
• Itchiness (pruritus). Many people on dialysis experience itchy skin. Causes include excess phosphate, wastes that dialysis cannot remove from the blood and mineral imbalances caused by overactive parathyroid glands. Treatments include low-phosphorus diet or phosphate binders, EPO injections, exposure to ultraviolet light, skin creams and removal of the parathyroid glands.
  
  
• Abnormal heart rhythm (arrhythmia). Electrolyte imbalances, such as too much potassium in the blood (hyperkalemia), can affect the heart rate. Avoiding potassium-rich foods can help.
  
  
• Amyloidosis. The accumulation of protein in the organs and tissues. Amyloidosis of the joints and tendons has symptoms similar to those of arthritis: stiffness, pain and fluid in the joints. Dialysis-related amyloidosis (DRA) is common in people who have been on dialysis for more than five years.
  
  
• Sleep disorders. People on dialysis often experience insomnia, which is often caused by aching in the legs (due to mineral imbalances). Treatment includes moderate exercise well before bedtime, warm baths, massages, medications, and avoiding caffeine, alcohol and tobacco. Some people on dialysis suffer from sleep apnea, interrupted breathing while asleep. This might result from disrupted control of breathing caused by kidney failure. Treatments for apnea include change of sleep position, weight loss and use of a mask that brings air into the nose.
  
  
• High blood pressure (hypertension). Elevated blood pressure is common among patients with diabetes and is of particular concern to patients with diabetes and kidney disease.

• Peripheral neuropathy (nerve damage in the limbs, hands and feet). Also a major problem for diabetic patients, it can worsen if waste products accumulate in the bloodstream.

People on chronic dialysis can lead fulfilling lives, but they have many responsibilities, particularly those associated with managing their diabetes or other complications. Concerns common to both types of dialysis include:

• Diet. People on dialysis have many special dietary needs. A dietician can help. Generally, an individual’s diet is more restricted with hemodialysis than with peritoneal dialysis. A closely controlled diet is necessary because hemodialysis is performed less frequently and more wastes gather in the body between treatments. A physician may prescribe specially designed vitamins and minerals to help with dietary requirements. Patients must avoid over-the-counter vitamins, supplements and medications without a nephrologist’s recommendation because they can provide dangerous levels of minerals and other substances. Dietary concerns include:
  
  
• • Protein. Because protein breaks down into the waste product blood urea nitrogen (BUN), predialysis patients are often put on a low-protein diet to keep the kidneys working as long as possible. After dialysis begins, however, emphasis is placed on eating high-quality proteins that produce less waste in the blood (e.g., meat, fish, poultry and egg whites).
    
    
  • Potassium. High-potassium foods can harm the heart by making it beat too fast. These include milk, yogurt, sardines, clams, and many fruits and vegetables including bananas, avocados, oranges, melons and dried fruits. Potatoes and other potassium-rich vegetables can be improved by peeling them, soaking them in water for a few hours and rinsing them.
    
    
  • Phosphorus. Excess phosphorus can weaken the bones and cause itchy skin (pruritus). High-phosphorus foods include milk, cheese, colas, nuts, dried beans and peas.
    
    
  • Fluids. It is important for dialysis patients to monitor daily consumption of liquids, including those found in foods. These individuals must follow the limits recommended by the physician or dietician. Consuming too much fluid can cause high blood pressure (hypertension), tax the heart and make dialysis less effective.
    
    
  • Salt. Too much sodium can raise blood pressure and result in drinking too much fluid. Many canned goods and processed foods are high in salt.
    
    
• Depression and stress. Emotional and psychological difficulties go hand in hand with the upheavals caused by dialysis. Often the toll on relationships, self-image and finances is heavy. Social workers, counselors, therapists and support groups can help with emotional support.
  
  
• Expense. Dialysis costs tens of thousands dollars a year. Medicare pays 80 percent for recipients requiring regular treatment. Medicaid, private insurance or state aid usually covers the remaining cost. A social worker can provide more information about financial assistance. People relying on home dialysis units, especially those in regions prone to hurricanes or other causes of power outages, may need to consider buying a generator.
  
  
• End-of-life decision making. Because of concerns about quality of life and other matters, one-fourth of the people on dialysis choose to end treatment. Unless a kidney transplant is available, death normally results within weeks. People undergoing dialysis should consider in advance such matters as living wills and power of attorney. Most people on dialysis, however, find the extension of life outweighs the inconveniences.

The two main variations of dialysis are hemodialysis and peritoneal dialysis. The only alternative to dialysis in cases of end-stage renal disease is a kidney transplant. There usually is a long wait for an organ, and transplant might not be an option in some cases, such as poor general health. Physicians determine if an individual on dialysis is a candidate for a kidney transplant.

Dialysis is most often used for chronic kidney failure but is also used in hospitals to treat some cases of acute kidney failure due to such factors as poisoning, infection, trauma or obstruction. Depending on its cause and course, acute kidney failure can sometimes be resolved instead with treatments such as antibiotics, diuretics and intravenous infusion of potassium exchange resin and other substances.

The best course for at-risk people, such as those with diabetes, high blood pressure or lupus, is to prevent kidney disease and the need for dialysis through early and careful control and monitoring. Prevention may include special testing by the physician for protein in the urine (a microalbuminuria test), other tests of kidney function such as glomerular filtration rate and waste product testing, management of blood pressure and glucose (blood sugar), diet and exercise, and possibly medication such as ACE inhibitors or other antihypertensives.

Preparing questions in advance can help patients have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following questions about dialysis:

1. Do I need or am I at risk of needing dialysis?
   
   
2. Can anything be done to prevent or delay my need for dialysis?
   
   
3. Is a kidney transplant or other treatment a possible alternative for me?
   
   
4. How do hemodialysis and peritoneal dialysis compare? Which do you recommend for me?
   
   
5. How often will my dialysis take place, and how long will my sessions be?
   
   
6. Can my dialysis be done at home, or do I need to go to a dialysis center?
   
   
7. If I do my dialysis at home, what sort of training is needed? Is a helper necessary?
   
   
8. What changes in my diet and other habits does dialysis require?
   
   
9. Can I be employed and enjoy other activities while undergoing dialysis?
   
   
10. What sort of financial, transportation and emotional support is available for me?
    
    
11. What kind of testing do I need to monitor kidney function and effectiveness of dialysis, and how often?
    
    
12. Should I complete a living will and other such documents?
    
    
13. What are the chances that I could regain enough kidney function to survive without dialysis?