Evaluating Elevated Hemoglobin

To the Editor In a JAMA Diagnostic Test Interpretation article, Drs Scherber and Mesa outlined the diagnostic steps in evaluation of an elevated hemoglobin level.1 We agree that JAK2 V617F gene mutation testing is among the options in the diagnostic algorithm for elevated hemoglobin, even in the presence of low-normal serum erythropoietin levels, because prompt treatment of polycythemia vera is warranted to reduce thrombotic risk