The Next Diagnostic Step in a Patient With Polycythemia

The next step in his evaluation would be for measurement of the RBC mass, because this will tell you if he has an absolute erythrocytosis or if it's just a relative. Usually if we find an elevated RBCMass, then we'll measure the erythropoietin or EPO levels to distinguish between polycythemia and other causes such as kidney cancer or lung disease. You could also consider an arterial blood gas to look for hypoxemia, and sometimes you see that in people who have bad lung disease. Obviously, pulmonary function tests would also be helpful in that case,. ultrasounds in PFTs would be later tests in the evaluation.