elevated platelets and megathrobocytes should I be scared

[Bunnyj1957]

On a routine CBC my platelets were 563 and all other blood work was within normal ranges. My Endo informed me that my platelets had been elevated since May and was referring me to a Hematologist. The Hematologist tells me that she wants to run additional blood work and depending on the outcome I might need a bone biopsy. The ANA was negative. No infection and no iron problems The lab sent a finding of normal cells with exception of increased megathrobocytes and platelets. They found no lymphoma or cancer cells, but recommended a bone biopsy for myeloproliferative/myelodysplastic disease. I feel fine with the exception of hip pain, heaviness in my legs and tingling in my legs and arms. I had thyroid cancer in January and 2 surgeries later and radiation therapy I am hopefully cured, but now I am scared to death that I could possibly have leukemia. Should I be concerned?

[Neil Cuadra]

Bunnyj1957,

From what I've read, your high platelet count, tingling, and heavy legs (which may be a sign of general weakness) match the symptoms of essential thrombocythemia, where the bone marrow makes too many megakaryocytes (future platelets). You've ruled out an iron problem or autoimmune reaction as the cause. It's possible but uncommon for essential thrombocythemia to lead to leukemia or myelofibrosis, so I don't think you should focus your worries in that direction. Essential thrombocythemia can be caused by the JAK2 gene, which genetic tests can identify.

Your symptoms also match the other form of thrombocytosis, not due to a bone marrow problem, called reactive thrombocytosis. It can result from an infection, but that's a cause you've already ruled out. It seems more likely to be a result of the cancer and surgeries you mentioned, since both are considered possible causes of reactive thrombocytosis. Reactive thrombocytosis can also result from use of certain drugs. Have you taken vincristine (Oncovin)? That's one of the drugs associated with reactive thrombocytosis.

In either case, some cases of thrombocytosis need to be treated and others do not. It depends on your apparent risk of blood clots and that's what your hematologist has to decide. But from the tests you've described it sounds to me (a caregiver, not a doctor) that your physicians have been doing exactly the right things to narrow down the possible causes of your symptoms and elevated platelet count. Let's hope it's one of the less serious causes.