The significance of thrombocytosis in old age.

We performed a retrospective study on 21 patients, aged 70 years or more, affected by polycythemia vera (PV) or essential thrombocythemia (ET). As controls, we evaluated 10 younger ET patients. The results indicate that in older ET subjects there was a lower incidence of hemorrhagic and thrombotic complications than in younger patients and PV patients. However, platelet number and platelet function tests were similar in all the patients studied. We suppose that an increase in hematocrit as seen in PV is much more dangerous as compared to an isolated increase in platelet count, and that thrombocytosis alone in old age can be an isolated expression of a natural involution of blood marrow similar to myelofibrosis.