In hemodialysis, a machine filters wastes, salts and fluid from your blood when your kidneys are no longer healthy enough to do this work adequately. Hemodialysis (he-moe-die-AL-uh-sis) is one way to treat advanced kidney failure and can help you carry on an active life despite failing kidneys.

With hemodialysis, you'll need to:

• Follow a strict treatment schedule
• Take medications regularly
• Make changes in your diet

Hemodialysis is a serious responsibility, but you don't have to shoulder it alone. You'll work closely with your health care team, including a kidney specialist and other professionals with experience managing hemodialysis. You may be able to do hemodialysis at home.

Your doctor will help determine when you should start hemodialysis based on several factors, including your:

• Overall health
• Kidney function
• Signs and symptoms
• Quality of life
• Personal preferences

You might notice signs and symptoms of kidney failure (uremia), such as nausea, vomiting, swelling or fatigue. Your doctor uses your estimated glomerular filtration rate (eGFR) to measure your level of kidney function. Your eGFR is calculated using your blood creatinine test results, sex, age and other factors. A normal value varies with age. This measure of your kidney function can help to plan your treatment, including when to start hemodialysis.

Hemodialysis can help your body control blood pressure and maintain the proper balance of fluid and various minerals — such as potassium and sodium — in your body. Normally, hemodialysis begins well before your kidneys have shut down to the point of causing life-threatening complications.

Common causes of kidney failure include:

• Diabetes
• High blood pressure (hypertension)
• Kidney inflammation (glomerulonephritis)
• Kidney cysts (polycystic kidney disease)
• Inherited kidney diseases
• Long-term use of nonsteroidal anti-inflammatory drugs or other medications that could harm the kidneys

However, your kidneys may shut down suddenly (acute kidney injury) after a severe illness, complicated surgery, heart attack or other serious problem. Certain medications also can cause kidney injury.

Some people with severe long-standing (chronic) kidney failure may decide against starting dialysis and opt for a different path. Instead, they may choose maximal medical therapy, also called maximum conservative management or palliative care. This therapy involves active management of complications of advanced chronic kidney disease, such as fluid overload, high blood pressure and anemia, with a focus on supportive management of symptoms that affect quality of life.

Other people may be candidates for a preemptive kidney transplant, instead of starting on dialysis. Ask your health care team for more information about your options. This is an individualized decision because benefits of dialysis may vary, depending on your particular health issues.

Most people who require hemodialysis have a variety of health problems. Hemodialysis prolongs life for many people, but life expectancy for people who need it is still less than that of the general population.

While hemodialysis treatment can be efficient at replacing some lost kidney function, you may experience some of the related conditions listed below, although not everyone experiences all of these issues. Your dialysis team can help you deal with them.

• Low blood pressure (hypotension). A drop in blood pressure is a common side effect of hemodialysis. Low blood pressure may be accompanied by shortness of breath, abdominal cramps, muscle cramps, nausea or vomiting.
• Muscle cramps. Although the cause is not clear, muscle cramps during hemodialysis are common. Sometimes the cramps can be eased by adjusting the hemodialysis prescription. Adjusting fluid and sodium intake between hemodialysis treatments also may help prevent symptoms during treatments.
• Itching. Many people who undergo hemodialysis have itchy skin, which is often worse during or just after the procedure.
• Sleep problems. People receiving hemodialysis often have trouble sleeping, sometimes because of breaks in breathing during sleep (sleep apnea) or because of aching, uncomfortable or restless legs.
• Anemia. Not having enough red blood cells in your blood (anemia) is a common complication of kidney failure and hemodialysis. Failing kidneys reduce production of a hormone called erythropoietin (uh-rith-roe-POI-uh-tin), which stimulates formation of red blood cells. Diet restrictions, poor absorption of iron, frequent blood tests, or removal of iron and vitamins by hemodialysis also can contribute to anemia.
• Bone diseases. If your damaged kidneys are no longer able to process vitamin D, which helps you absorb calcium, your bones may weaken. In addition, overproduction of parathyroid hormone — a common complication of kidney failure — can release calcium from your bones. Hemodialysis may make these conditions worse by removing too much or too little calcium.
• High blood pressure (hypertension). If you consume too much salt or drink too much fluid, your high blood pressure is likely to get worse and lead to heart problems or strokes.
• Fluid overload. Since fluid is removed from your body during hemodialysis, drinking more fluids than recommended between hemodialysis treatments may cause life-threatening complications, such as heart failure or fluid accumulation in your lungs (pulmonary edema).
• Inflammation of the membrane surrounding the heart (pericarditis). Insufficient hemodialysis can lead to inflammation of the membrane surrounding your heart, which can interfere with your heart's ability to pump blood to the rest of your body.
• High potassium levels (hyperkalemia) or low potassium levels (hypokalemia). Hemodialysis removes extra potassium, which is a mineral that is normally removed from your body by your kidneys. If too much or too little potassium is removed during dialysis, your heart may beat irregularly or stop.
• Access site complications. Potentially dangerous complications ― such as infection, narrowing or ballooning of the blood vessel wall (aneurysm), or blockage ― can impact the quality of your hemodialysis. Follow your dialysis team's instructions on how to check for changes in your access site that may indicate a problem.
• Amyloidosis. Dialysis-related amyloidosis (am-uh-loi-DO-sis) develops when proteins in blood are deposited on joints and tendons, causing pain, stiffness and fluid in the joints. The condition is more common in people who have undergone hemodialysis for several years.
• Depression. Changes in mood are common in people with kidney failure. If you experience depression or anxiety after starting hemodialysis, talk with your health care team about effective treatment options.

Preparation for hemodialysis starts several weeks to months before your first procedure. To allow for easy access to your bloodstream, a surgeon will create a vascular access. The access provides a mechanism for a small amount of blood to be safely removed from your circulation and then returned to you in order for the hemodialysis process to work. The surgical access needs time to heal before you begin hemodialysis treatments.

There are three types of accesses:

• Arteriovenous (AV) fistula. A surgically created AV fistula is a connection between an artery and a vein, usually in the arm you use less often. This is the preferred type of access because of effectiveness and safety.
• AV graft. If your blood vessels are too small to form an AV fistula, the surgeon may instead create a path between an artery and a vein using a flexible, synthetic tube called a graft.
• Central venous catheter. If you need emergency hemodialysis, a plastic tube (catheter) may be inserted into a large vein in your neck. The catheter is temporary.

It's extremely important to take care of your access site to reduce the possibility of infection and other complications. Follow your health care team's instructions about caring for your access site.

You can receive hemodialysis in a dialysis center, at home or in a hospital. The frequency of treatment varies, depending on your situation:

• In-center hemodialysis. Many people get hemodialysis three times a week in sessions of 3 to 5 hours each.
• Daily hemodialysis. This involves more-frequent, but shorter sessions — usually performed at home six or seven days a week for about two hours each time.

Simpler hemodialysis machines have made home hemodialysis less cumbersome, so with special training and someone to help you, you may be able to do hemodialysis at home. You may even be able to do the procedure at night while you sleep.

There are dialysis centers located throughout the United States and in some other countries, so you can travel to many areas and still receive your hemodialysis on schedule. Your dialysis team can help you make appointments at other locations, or you can contact the dialysis center at your destination directly. Plan ahead to make sure space is available and proper arrangements can be made.

The procedure

During treatments, you sit or recline in a chair while your blood flows through the dialyzer ― a filter that acts as an artificial kidney to clean your blood. You can use the time to watch TV or a movie, read, nap, or perhaps talk to your "neighbors" at the center. If you receive hemodialysis at night, you can sleep during the procedure.

• Preparation. Your weight, blood pressure, pulse and temperature are checked. The skin covering your access site — the point where blood leaves and then reenters your body during treatment — is cleansed.
• Starting. During hemodialysis, two needles are inserted into your arm through the access site and taped in place to remain secure. Each needle is attached to a flexible plastic tube that connects to a dialyzer. Through one tube, the dialyzer filters your blood a few ounces at a time, allowing wastes and extra fluids to pass from your blood into a cleansing fluid called dialysate. The filtered blood returns to your body through the second tube.
• Symptoms. You may experience nausea and abdominal cramps as excess fluid is pulled from your body — especially if you have gained a significant amount of fluid in between dialysis sessions. If you're uncomfortable during the procedure, ask your care team about minimizing side effects by such measures as adjusting the speed of your hemodialysis, your medication or your hemodialysis fluids.
• Monitoring. Because blood pressure and heart rate can fluctuate as excess fluid is drawn from your body, your blood pressure and heart rate will be checked several times during each treatment.
• Finishing. When hemodialysis is completed, the needles are removed from your access site and a pressure dressing is applied to the site to prevent bleeding. Your weight may be recorded again. Then you're free to go about your usual activities until your next session.

If you had sudden (acute) kidney injury, you may need hemodialysis only for a short time until your kidneys recover. If you had reduced kidney function before a sudden injury to your kidneys, the chances of full recovery back to independence from hemodialysis are lessened.

Although in-center, three-times-a-week hemodialysis is more common, some research suggests that home dialysis is linked to:

• Better quality of life
• Increased well-being
• Reduced symptoms and less cramping, headaches and nausea
• Improved sleeping patterns and energy level

Your hemodialysis care team monitors your treatment to make sure you're getting the right amount of hemodialysis to remove enough wastes from your blood. Your weight and blood pressure are monitored very closely before, during and after your treatment. About once a month, you'll receive these tests:

• Blood tests to measure urea reduction ratio (URR) and total urea clearance (Kt/V) to see how well your hemodialysis is removing waste from your body
• Blood chemistry evaluation and assessment of blood counts
• Measurements of the flow of blood through your access site during hemodialysis

Your care team may adjust your hemodialysis intensity and frequency based, in part, on test results.

Between treatments

Between hemodialysis treatments, you can help achieve the best possible results from your hemodialysis if you:

• Eat the right foods. Eating properly can improve your hemodialysis results and your overall health. While you're receiving hemodialysis, you'll need to carefully monitor your intake of fluids, protein, sodium, potassium and phosphorus. A dietitian can help you develop an individualized meal plan based on your weight, personal preferences, remaining kidney function and other medical conditions, such as diabetes or high blood pressure.
• Take your medications as prescribed. Carefully follow the instructions from your health care team.
• Allow your team to assist you by discussing your concerns. Your health care team can present options to you and help you deal with any concerns.