Lupak O, et al. - Researchers examined the value of low erythropoietin (EPO) level in polycythemia vera (PV) diagnosis in the context of positive JAK2 mutation status as well as other diagnostic parameters. They examined 138 patients; of these, 75 patients had PV and 63 had secondary erythrocytosis. EPO levels were within the normal range among 32% of the 75 patients with PV. They observed a positive correlation between EPO level and obesity and smoking status, making it an unreliable diagnostic marker in those patients. For PV, positive JAK2V617F demonstrated a strong predictive value either alone or in combination with other variables.