POLYCYTHEMIA VERA

I. Definitions and pathophysiology

1. A myeloproliferative disorder characterized by consistently elevated RBC counts
2. Diagnostic criteria--All 3 major criteria or the first 2 major criteria + any two minor criteria (Am. J. Med. 109:141, 2000--AFP):
   1. Major criteria
      1. RBC mass > 36mL/kg for men or > 32mL/kg for women
      2. SaO2 > 92%
      3. Splenomegaly
   2. Minor criteria
      1. Platelet count > 400,000/uL
      2. WBC count > 12,000/uL
      3. Serum alkaline phosphatase > 100U/L
      4. Serum B12 level > 900pg/mL
      5. Unbound B12 binding capacity > 2,200pg/mL
3. Associated with risk of abnormal thrombosis (unclear if risk correlates with degree of polycythemia) and, more rarely, hemorrhage

II. Clinical presentation

1. Thrombotic events
2. Hemorrhage
3. Headache
4. Transient neurologic or ocular sx
5. Paresthesias
6. Pruritis after bathing

III. Treatment

1. Phlebotomy
2. Hydroxyurea
3. 518 pts w/polycythemia vera (90% with no prior h/o thombotic event) randomized to ASA 100mg QD vs. placebo; over mean 3y f/u, incidence of (MI, CVA, PE, major venous thrombosis, or CV death) was sig. less in ASA group (3% vs. 8%); no sig. diff. in major bleeding between the groups (NEJM 350:114, 2004--JW)