Schafer outlined the approach to management of a patient with primary thrombocythemia. The author is from the University of Pennsylvania Health System in Philadelphia.
Patient selection: A patient with a primary (clonal) thrombocytosis and platelet count > 450,000 per µL.
Parameters:
(1) symptomatic status
(2) platelet count
(3) age
(4) cardiovascular risk factors
(5) history (thrombosis, bleeding)
(6) thrombosis present
(7) active ischemia (cerebrovascular, digital, other)
Rule |
Management |
symptomatic with active ischemia |
immediate cytoreduction (consider plateletpheresis); antiplatelet therapy |
symptomatic with history of bleeding or thrombosis, thrombosis present |
cytoreduction; antiplatelet therapy |
symptomatic with history of bleeding or thrombosis |
cytoreduction |
asymptomatic but at high risk (age > 60 years or cardiovascular risk factors) |
cytoreduction; antiplatelet therapy |
asymptomatic with history of bleeding or thrombosis |
cytoreduction |
asymptomatic with platelet count > 1.5 million per µL |
cytoreduction |
asymptomatic not at high risk with platelet count <= 1.5 million per µL |
follow without therapy |
where:
• The rules are not hard and fast. For example, I would imagine that cytoreduction might be done at a lower platelet count, especially if it was rising sharply.
• A symptomatic person with active (not just history of) bleeding would be treated with cytoreduction but I am not sure about the use of aspirin (see below).
• Cytoreduction for asymptomatic history of bleeding or thrombosis is not shown in Figure 3, but is indicated as a risk factor in the text on page 1215.
Cytoreduction is usually achieved by therapy with
(1) hydroxyurea
(2) anagrelide
(3) interferon alpha (may have intolerable side effects). This is the treatment of choice for a younger woman who may become pregnant (hydroxyurea is teratogenic; anagrelide is not known to be safe)
(4) alkylating agents in an older patient who cannot tolerate other therapy (use in younger patients is avoided due to risk of acute leukemia)
The preferred antiplatelet therapy would be aspirin but other agents may be required if a patient cannot tolerate aspirin. Low doses of aspirin are often effective without increasing the risk of excessive bleeding.
Specialty: Hematology Oncology
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