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Epic search launched for cause of high hemoglobin level

BY KEITH ROACH, M.D.

DEAR DR. ROACH: I am a 51-year-old male in very good health. I have had blood tests taken yearly for the past 15+ years. Nearly every test shows high hemoglobin. My average is 17.4, but has been as high as 18.1 within the past several years. (Anything above 17.5 is considered high.)

My primary care physician was never concerned. He said that my numbers were not much over the threshold and that as long as the numbers hold steady and are not increasing, there is nothing I should do about it.

He retired a year ago, and my new doctor is very concerned. I was sent to a hematologist, who also was concerned about the high hemoglobin. We discussed what could cause this, and ruled out everything — including using performance enhancing drugs, sleep apnea, etc. She ran another set of blood tests to check for genetic markers for polycythemia vera. They came back negative. I did not have a bone marrow biopsy nor a test for erythropoietin.

Is there any reason to keep searching for a cause when it seems I’ve exhausted the list? The primary concern is that I am at an increased risk of blood clotting that could cause a stroke or heart attack, so my doctor suggested I take baby aspirin. Should I have my blood’s clotting ability tested? Can I continue to donate blood? — L.B.

ANSWER: The first step in deciding what to do after an unexpected test result is to decide whether it is really abnormal. The range of “normal” values provided by the laboratory represent where 95% of people without apparent illness would be. That means 5% of healthy people will have a lab result that is outside the published range. If you do 20 lab tests, which isn’t uncommon, 36% of people will have at least one abnormal result.

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.

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