A high red blood cell count indicates there are too many red blood cells circulating in your bloodstream. Red blood cells (RBCs), also called erythrocytes, are produced in your bone marrow and transport oxygen from your lungs to tissues throughout your body. A high red blood cell count is also called erythrocytosis (uh-rith-roh-sie-TOE-sis).

The threshold for a high red blood cell count is somewhat different from one medical practice to another. A high red blood cell count is generally defined as more than 5.72 million red blood cells per microliter (mcL) of blood for men and 5.03 million per mcL for women. In children, the threshold for high red blood cell count varies with age and sex.

A high red blood cell count is rarely an unexpected finding or simply discovered by chance. It's usually found when your doctor has ordered tests to help diagnose a condition you have. Talk to your doctor about what these results mean. A high red blood cell count and results from other tests may indicate the cause of your illness, or your doctor may suggest additional tests to monitor your condition.

Jan. 25, 2013