What Dialysis Can and Cannot Do

Many people assume dialysis replaces the function of healthy kidneys. This is partially true. The primary job of the kidneys is to remove excess fluid and waste from the bloodstream. When your kidney function is below 15 percent of normal, you need dialysis to filter these items from your blood. But your kidneys have other duties as well. They make and release hormones that regulate and control certain body functions. Unfortunately, dialysis is unable to manufacture these essential hormones. Patients in the later stages of chronic kidney disease (CKD) will need medical supplements to compensate for the hormones their kidneys are unable to produce.

Dialysis removes fluid and wastes

The main purpose of dialysis is to replace impaired renal function. When your kidneys are damaged, they are no longer able to remove wastes and excess fluid from your bloodstream efficiently. Waste such as nitrogen and creatinine build up in the bloodstream. If you have been diagnosed with CKD, your doctor will have these levels carefully monitored. One of the best indicators of kidney function is your glomerular filtration rate (GFR). Your GFR tells your doctor how well your kidneys are filtering waste from your blood.

If your GFR level is below 15, dialysis becomes necessary. Before dialysis, patients often felt weak and ill. Dialysis brings relief from these symptoms. This is the primary benefit of dialysis.

Dialysis helps regulate electrolytes

Electrolytes are certain minerals the body needs to function correctly. They are important for our overall health. We get most of these minerals from the foods we eat. But too much or too little can make you sick. Healthy kidneys help control the levels of electrolytes by filtering the excess and keeping what is needed.

For patients with CKD, following their renal dietitian’s recommendations is an important aspect of regulating electrolytes. A renal diet provides good all-around nutrition while limiting proteins and certain minerals. Your dialysis session becomes more effective, and you will feel better as a result.

Dialysis can’t replace hormones

Your kidneys are part of the body’s endocrine system. The endocrine system controls certain body functions by making and releasing hormones into the bloodstream. When your kidneys are damaged, they may produce very little hormones or none at all. Unfortunately, dialysis cannot replace or manufacture these chemicals. These will need to be replaced in the body with medication.

Calcitriol helps your body absorb calcium

One of the hormones your kidneys produce is calcitriol (vitamin D). Calcitriol allows your body to absorb calcium from the foods you eat. Without it, your body would be unable to get enough calcium, even if you are taking calcium supplements. Calcium has many functions in the body. One of its main functions is keeping bones strong. A lack of calcium can make bones weak and brittle. Calcium is also important in maintaining a normal heartbeat and keeping your nerves and muscles functioning properly. If your kidneys are not producing enough calcitriol, your doctor may choose to prescribe a vitamin D supplement such as prescribe ZEMPLAR®.

Erythropoietin signals red blood cell production

Another hormone your kidneys produce is erythropoietin. Erythropoietin sends a chemical message to your bone marrow to make red blood cells. Red blood cells are the cells that transport needed oxygen throughout the body. Without adequate levels of oxygen, your body’s cells will not have the energy to do their jobs. If your red blood cell count is too low, you may develop anemia. Anemia will make you feel dizzy and weak, a sign that there is not enough oxygen making its way throughout your body. If you are anemic, your doctor will prescribe EPOGEN® or EPO be given to you during your dialysis treatment.

Renin helps regulate blood pressure

Renin is an enzyme your kidneys make. Its primary job is to regulate blood pressure. However, some patients with CKD produce too much renin. Excess renin can cause your blood pressure to rise. If you have already been diagnosed with high blood pressure, too much renin can elevate your pressure even more. High blood pressure is the second most common cause of CKD. It can also accelerate kidney damage. Your doctor may prescribe a medication to help lower your blood pressure.


Dialysis is the primary procedure used to treat patients in the later stages of chronic kidney disease. However, additional medicine may be needed to replace enzymes and hormones. It is important to follow your health care team’s recommendations regarding treatment. Your overall health depends on treating the lack of renal and endocrine functions of your kidneys.