Thrombocytosis Secondary

Question: Primary or Secondary Thrombocytosis/Polycythemia Vera? I had some initial blood work done on a routine visit to the doctor. I was notified the next day that I had a platelet count of 1,200,000. This was about three weeks ago. It has since declined to 900,000 then down to 898,000. Does it decline naturally when you have a myeloproliferative disorder? I have been very afraid and concerned and have relatively no symptoms. No bruising, no fever, no loss of appetite, no enlarged liver or spleen. I don't have history of cancers in the family. They looked at my platelets and they were NOT misshapen or malformed. Everything else about my blood is normal. White/Red Counts, etc. I feel generally fit and am 24 years old. Next step I think is a bone marrow sample. Any hope out there? What do you think it is? No copy and pasting from wikipedia please. I want an educated, intelligent answer. I also had an inflammatory test done and the test came back normal.

Answer: This is a high platelet count. Diagnosis of a myeloproliferative disorder (in this case essential thrombocythemia or ET) would require classically at least 3 successive platelet counts in a row >600,000, which you have met. Ruling out iron deficiency (check ferritin) or other inflammatory/infectious state is important. Additionally one would usually see larger-than-usual platelet precursors (megakaryocytic hyperplasia) on a bone marrow. A newer blood test, JAK2 mutation, is also frequently positive, and then usually we rule out chronic myeloid leukemia by testing for BCR/ABL in the blood as well. I have many myeloproliferative patients and yes there counts can fluctate a fair bit at times. Not all patients with ET require therapy. Given you are young, healthy and platelets <1.5 million, no therapy and close observation is a reasonable option (see link below). Others might require therapy. In your case, there is a trend downward so certainly bears following to see how low will go. In any case, ET can be associated with NORMAL life expectancy for most patients. There is a slight risk for progression to leukemia, fibrosis of bone marrow, and risk for blood clots (cumulative risk about 2%, 4%, and 17% over 15 years in one study). This is why bone marrow is helpful and why you need to be followed. God bless, best wishes