Low red blood cells or hemoglobin called anemia is the most common blood disorder world-wide. However, some patients have hemoglobin that is too high called polycythemia. Polycythemia can be caused by a bone marrow disorder caused polycythemia vera or from other causes outside the bone marrow called secondary polycythemia. Distinguishing between the two became much easier about ten years ago with the discovery and testing for Janus Kinase 2 (JAK-2) mutations. Janus was the Roman god of gates and this protein regulates the production of red bloods cells. When is mutated, red blood cells are continuously produced causing a high hemoglobin. Treatment of polycythemia vera is removal of the extra blood in a process called phlebotomy.
Secondary polycythemia can be caused by conditions that cause low oxygen levels in the blood. Extra red blood cells are then produced as a compensation. Common causes include tobacco smoking and sleep apnea. Other causes can include congenital heart disease, carbon monoxide exposure and being born with an abnormal type of hemoglobin. The best treatment for secondary polycythemia is treating the underlying condition such as smoking cessation or the treatment of the sleep apnea.