Low hemoglobin levels, anemias, are very common, but high hemoglobin levels are much less so. It seems your former primary care physician determined that your hemoglobin result was normal for you, but your new doctor wasn’t so sure. An evaluation for the most common causes of high hemoglobin is reasonable, as some of them are quite serious. Polycythemia vera is a blood cancer, but the genetic tests you had make polycythemia vera unlikely.

I am surprised you did not have an erythropoietin level, as most experts find that is an important test to evaluate high hemoglobin levels. A high EPO level indicates that something is stimulating your bone marrow to make more red blood cells. Sleep apnea was one good thought; high altitude, a defect in the wall of the heart, carbon monoxide poisoning and, rarely, EPO-producing tumors would be worth considering. A low EPO level would be more suggestive of polycythemia vera.

Abnormal blood clotting is a critical issue in polycythemia vera, which is partly why it is critical to make the correct diagnosis. Deciding whether to go further in your evaluation — getting the EPO level, and if it’s low, then getting the definitive bone marrow biopsy — requires judgment. It also requires knowing how confident a patient needs to be. Some people are very uncomfortable living with uncertainty.

Continuing to give blood will help both you and your community, provided you have no medical conditions causing the high hemoglobin level.