Essential Thrombocytosis Follow-up

Updated: Aug 11, 2021
  • Author: Asheesh Lal, MBBS, MD; Chief Editor: Emmanuel C Besa, MD  more...
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Thrombosis may be serious and life threatening in patients with essential thrombocytosis (primary thrombocythemia). Bleeding is usually from the gastrointestinal tract and is, in most cases, mild.

Transformation to acute myelogenous leukemia (AML) occurs in 0.6-5% of patients with essential thrombocytosis; the risk may be comparable to that of the healthy population. In an Italian series of 2316 retrospectively collected cases, the rate of transformation to AML or myelodysplastic syndrome was 1% in patients left untreated. [49] Use of interferon or hydroxyurea elicited a similar rate of AML or myelodysplastic syndrome, whereas transformation occurred in 4% of patients treated with alkylators. [49]

Hydroxyurea does not appear to increase the risk of transformation to AML in older patients when used as the sole agent for treatment of essential thrombocytosis (primary thrombocythemia). Whether prolonged use, as needed in younger patients, may be associated with an increased risk of transformation to AML is unclear.

Patients with essential thrombocytosis in whom hydroxyurea therapy fails and who are then treated with alkylating agents or phosphorus-32 have a higher risk of developing AML. Anagrelide or interferon alfa may be good therapeutic options in patients for whom hydroxyurea therapy fails.

Transformation to polycythemia vera and agnogenic myeloid metaplasia may occur in patients with essential thrombocytosis. Spontaneous abortion, intrauterine death, or intrauterine growth retardation may complicate pregnancy.



The life expectancy of patients with essential thrombocytosis (primary thrombocythemia) is nearly that of the healthy population. Median survival is approximately 20 years. For patients younger than age 60 years, median survival is 33 years. [10]