A Diagnostic Roadmap for Polycythemia

Abstract

Polycythemia could be defined as an elevation in hemoglobin or hematocrit levels above normal. To figure out what induces polycythemia is very important since the causes of polycythemia are very variable and the approaches for the treatments are basically different. Polycythemia can be primary or secondary in origin. The secondary causes are all associated with increase in erythropoietin (EPO) levels. If serum EPO levels are elevated, one try to differentiate whether the elevation is a physiologic response to hypoxemia or is related to autonomous production. Patients with low arterial O<sub>2</sub> saturation (< 92%) should be further evaluated for the presence of heart or lung disease. Patients without hypoxemia who are smokers may have elevated EPO levels because of CO displacement of O<sub>2</sub>. If carboxyhemoglobin levels are elevated, the diagnosis is smoker’s polycythemia. Patients without hypoxemia who do not smoke, either could be diagnosed as high oxygen affinity hemoglobinopathy or have EPO producing tumors. If EPO levels are low, the patients most likely have polycythemia vera which has almost JAK2 mutation.