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What Is Dialysis?

The kidneys are a pair of organs, each about the size of a fist, located on either side of your spine. They’re responsible for purifying your blood by removing waste and excess fluid from your body. When the kidneys don’t work properly, dialysis is used to perform the function of the kidneys.

Dialysis is a treatment that filters and purifies the blood using a machine. This helps keep your body in balance when the kidneys can’t do their job. Dialysis has been used since the 1940s to treat people with kidney problems.

Why Is Dialysis Used?

Properly functioning kidneys prevent extra water, waste, and other impurities from accumulating in your body. They also help control blood pressure and regulate the levels of chemicals in the blood, such as sodium, or salt, and potassium. They even activate a form of vitamin D that improves the absorption of calcium.

When your kidneys can't perform these functions due to disease or injury, dialysis can help keep the body running as normally as possible. Without dialysis, salts and other waste products will accumulate in the blood and poison the body. However, dialysis isn’t a cure for kidney disease or other problems affecting the kidneys. Different treatments may be needed to address those concerns.

How Does Dialysis Work?

Dialysis is an artificial way of cleaning your blood. There are two different types of dialysis:


Hemodialysis is the most common type of dialysis. It uses an artificial kidney, known as a hemodialyzer, to remove waste and chemicals from your blood. To get the blood to flow to the artificial kidney, your doctor will surgically create a vascular access, or an entrance point, into your blood vessels. This vascular access will allow a larger amount of blood to flow through your body during hemodialysis treatment. This means more blood can be filtered and purified.

The two type of vascular access designed for long-term dialysis treatments are an arteriovenous (AV) fistula, which connects an artery and a vein and an AV graft, which is a looped tube. For short-term use, a catheter may be inserted into the large vein in your neck.

Hemodialysis treatments usually last three to five hours. The treatment is typically needed three times per week. However, hemodialysis treatment can also be done in shorter, more frequent sessions.

Most hemodialysis treatments are done at a hospital, doctor's office, or dialysis center. The length of treatment depends on your body size and the amount of waste in your body.

After you’ve been on hemodialysis for an extended amount of time, your doctor may feel that you're ready to give yourself dialysis treatments at home. This option is more common for people who will need long-term treatment.

Peritoneal Dialysis

Peritoneal dialysis involves surgery to implant a catheter into your belly area. During treatment, a special fluid called dialysate flows into your abdomen. Once the dialysate draws waste out of the bloodstream, it’s drained from your abdomen.

There are numerous different types of peritoneal dialysis, but the main ones are continuous ambulatory peritoneal dialysis and continuous cycler-assisted peritoneal dialysis. In continuous ambulatory peritoneal dialysis, your abdomen is filled and drained multiple times each day. Continuous cycler-assisted peritoneal dialysis, however, uses a machine to cycle the fluid in and out of your abdomen. It’s usually done at night while you sleep.

Peritoneal dialysis can be done at home. You’ll receive training on how to perform the steps of the treatment.

Are There Any Risks Associated with Dialysis?

While both peritoneal dialysis and hemodialysis are treatments that can save your life, they can have certain risks.

Peritoneal dialysis is associated with an increased risk for infections in or around the catheter site in the abdominal cavity. For example, a person can experience peritonitis, an infection of the membrane lining the abdominal wall, after catheter implantation. Other risks include:

  • abdominal muscle weakening
  • high blood sugar due to the dextrose in the dialysate
  • weight gain

Hemodialysis also has unique risks, including:

  • low blood pressure
  • anemia, or not having enough red blood cells
  • muscle cramping
  • difficulty sleeping
  • itching
  • high blood potassium levels
  • depression
  • pericarditis, which is an inflammation of the membrane around the heart

If you continue to have these symptoms while on peritoneal dialysis or hemodialysis, tell the healthcare provider performing the treatment.

Those who undergo long-term dialysis treatments are also at risk of developing other medical conditions, including amyloidosis. This disease can occur when amyloid proteins produced in bone marrow build up in the kidneys, liver, heart, and other organs. This usually causes joint pain, stiffness, and swelling. Some people may also develop depression after being diagnosed with long-term kidney failure. Call 911 immediately if you’re having thoughts associated with depression, such as thoughts of harming yourself or committing suicide. The National Alliance on Mental Illness can also provide you with resources if you struggle with depression.

How Do I Prepare for Dialysis?

Before your first dialysis treatment, your doctor will surgically implant a tube or device to gain access to your bloodstream. This is typically a quick operation. You should be able to return home the same day.

It's best to wear comfortable clothing during your dialysis treatments. You should also follow your doctor's instructions, which may include fasting for a certain amount of time before the treatment.

What Is the Long-Term Outlook for Someone Who Needs Dialysis?

Not all kidney disorders are permanent. Dialysis can temporarily serve the same function as kidneys until your own kidneys repair themselves and begin to work on their own again. However, in chronic kidney disease, the kidneys rarely get better. You must go on dialysis permanently or until a kidney transplant becomes an option if you have this condition.

Content licensed from:

Written by: Brian Krans
Medically reviewed on: Dec 02, 2015: Jeanne Morrison, PhD, MSN

This feature is for informational purposes only and should not be used to replace the care and information received from your health care provider. Please consult a health care professional with any health concerns you may have.
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