Contributor: Gordon K. Klintworth
Erythema (polycythemia vera, polycythemia rubra, primary polycythemia, Vaquez-Osler disease, idiopathic polycythemia) is an idiopathic disease characterized by a marked increase in the number of circulating erythrocytes, an elevated hematocrit (men >54%, women >47%) and evidence of increased hematopoiesis. It usually becomes manifest during mid life (~35 years of age). Neurologic symptoms (headaches, tinnitus, vertigo, blurring of vision, loss of consciousness, and convulsions) are common (~34% of cases). Other manifestations include dyspnea, weakness, hypertension (42% of cases), hepatomegaly (50% of cases), and splenomegaly (90% of cases). An increased blood viscosity reduces the blood flow in the circulation and the hemoglobin in the circulating blood becomes reduced. Variable degrees of cyanosis become apparent in the face and distal extremities depending on amount of reduced hemoglobin in the circulation. Idiopathic polycythemia often culminates in leukemia or anemia. The blood viscosity increases exponentially with the hematocrit and predisposes to thrombosis and  varicosities in veins. Sequelae of thrombosis include phlebitis, portal hypertension, esophageal varices and perhaps peptic ulcer. Idiopathic polycythemia needs to be differentiated from secondary polycythemia [polycythemia - secondary].