Polycythemia

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Medical Author:

Siamak T. Nabili, MD, MPH

Siamak T. Nabili, MD, MPH

Dr. Nabili received his undergraduate degree from the University of California, San Diego (UCSD), majoring in chemistry and biochemistry. He then completed his graduate degree at the University of California, Los Angeles (UCLA). His graduate training included a specialized fellowship in public health where his research focused on environmental health and health-care delivery and management.

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Medical Editor:

Melissa Conrad Stöppler, MD, Chief Medical Editor

Melissa Conrad Stöppler, MD, Chief Medical Editor

Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

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• Polycythemia Overview
• Polycythemia Primary Causes
• Polycythemia Secondary Causes
• Relative Polycythemia
• Stress Polycythemia
• Polycythemia Risk Factors
• Polycythemia Symptoms
• When to Seek Medical Care
• Exams and Tests
• Polycythemia Treatment
• Self-Care at Home
• Medical Treatment
• Next Steps
• Follow-up
• Prevention
• Outlook
• Synonyms and Keywords
• Author and Editor
• Read more on Polycythemia (High Red Blood Cell Count) from Healthwise

Polycythemia is an increased number of red blood cells in the blood. In polycythemia, the levels of hemoglobin (Hgb), hematocrit (Hct), or the red blood cell (RBC) count may be elevated when measured in the complete blood count (CBC), as compared to normal. Hemoglobin levels greater than 16.5 g/dL (grams per deciliter) in women and greater than 18.5 g/dL in men suggest polycythemia. In terms of hematocrit, a value greater than 48 in women and 52 in men is indicative of polycythemia.

Production of red blood cells (erythropoiesis) occurs in the bone marrow and is regulated in a series of specific steps. One of the important enzymes regulating this process is called erythropoietin (Epo). The majority of Epo is produced and released by the kidneys, and a smaller portion is released by the liver.

Polycythemia can result from internal problems with the production of red blood cells. This is termed primary polycythemia. If polycythemia is caused due to another underlying medical problem, it is referred to as secondary polycythemia.

Most cases of polycythemia are secondary and are caused by another medical condition. Primary polycythemias are relatively rare; for example, polycythemia vera occurs in approximately 1 to 2 adults per 100,000 in the United States. One percent to five percent of newborns can have polycythemia (neonatal polycythemia).

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