Polycythemia With an Identifiable Cause

Sometimes the body produces too many red blood cells, and no cause can be identified. This disorder is called polycythemia vera. When a cause can be identified, the disorder is called secondary polycythemia.

Secondary polycythemia can result from the following:

• Conditions that prevent the body's tissues from getting enough oxygen. Examples are smoking, spending time at a high altitude, and having a severe lung disorder or heart failure.
• Conditions that reduce the amount of fluid (plasma) in the blood. In such cases, the percentage of red blood cells in the blood (hematocrit) increases even though the number is normal. These conditions include burns, vomiting, diarrhea, and use of drugs that increase the amount of salt and water excreted by the kidneys (diuretics). Not drinking enough fluids can also reduce the amount of plasma in the blood.
• Cysts in the kidneys or tumors in the kidneys, liver, or brain that produce erythropoietin. Erythropoietin is a hormone that stimulates the bone marrow to produce red blood cells. These cysts and tumors are rare.

Symptoms of secondary polycythemia are similar to those of polycythemia vera but are usually much milder.

If possible, the condition causing polycythemia is corrected or treated. Depending on the cause, oxygen given by nasal prongs, phlebotomy, or fluids given by mouth or intravenously may be appropriate. Smokers are advised to stop smoking and are offered specific treatment to help them. People who live at high altitudes may be advised to move to lower altitudes if possible.

Generally, the outlook for people with secondary polycythemia is much better than for those with polycythemia vera. Secondary polycythemia, unlike polycythemia vera, does not progress to leukemia.