Increase in platelets deserves diagnosis

Dear Dr. Roach: My wife is 58 years old, in good health, exercises and gets regular checkups. The bloodwork from those checkups has shown that her platelet count was 400 a year ago, 600 six months ago and 800 a couple weeks ago. She went to a hematologist who had little more information than her internist on why it’s happening. My wife has no other symptoms like bruising, bleeding, headaches, tiredness or vision issues. Her blood pressure is within the normal range. The hematologist wants to prescribe blood thinners. The next step will be a bone marrow biopsy. What are the causes of platelet counts dramatically increasing like that? — Anon.

I find the treatment of (and communication about) your wife’s condition frustrating (I’m being kind). You and your wife deserve to have the correct diagnosis and a thorough explanation of her treatment options. By far, the most likely diagnosis is essential thrombosis (“essential” in this context means we don’t know what causes it; the “thrombosis” means “too many blood-clotting cells,” otherwise known as platelets). ET is a chronic myeloproliferative neoplasm, a type of blood cell cancer. Most people with this disease have a mutation in the blood cell (an acquired mutation, one not present at birth) causing the cells that make platelets to proliferate in the bone marrow. She will also be tested for the JAK2 mutation since that has important information to help predict the course of her disease. Treatment for symptoms is not appropriate if she has no symptoms. The goals of treatment are to prevent complications of this disease (abnormal clotting is the major concern: bleeding is less common) and to be alert for transformation to a more aggressive disease, acute myelogenous leukemia. I’d like to hear back from you after the biopsy.