1. Increased red cell mass
Men> 36 mL/Kg Women>32 mL/Kg
2. Normal arterial O2 saturation >92%
1. Platelets>400 X 10e3
2. Leukocytes>12 X 10e3
3. LAP level>100
4. B12 level >900 pg/mL or unbound B12 binding capacity>2200 pg/mL
To make the diangosis require all three major criteria or presence of the first two major criteria & any two minor criteri.
Polycythemia vera Diagnostic work up (pdf format). Click to dwonload the file!
Diagnosis of polycythemia vera is not always an easy one! One can use serum erythropoietin levels to aid in the diagnosis. Download the diagnostic work up for details!
Use of serum erythropoietin levels:
1. Only about 50% of patients with secondary erythrocytosis have raised serum erythropoietin levels.
2. About 66% of patients with PCV have reduced erythropoietin levels.The reduced values persist even when the PCV lowered by treatment.
Polycythemia Vera-related Clinical & Laboratory Features:
Persistent Leukocytosis: 21-43% prevalence
Persistent thrombocytosis: 48-63%
Microcytosis due to iron deficiency: 50-80%
Palpable splenomegaly: 70%
Generalized pruritus (after bathing): 46%
Unusual thrombosis: 10%
The median age at diagnosis is approximately 60 years, & the disorder is slightly more common among men. Approximately 20% of patients present with thrombotic events, and the risk of recurrent thrombosis is greater for older patients and for those with a history of thrombosis. Bleeding complications are less frequent & less serious than thrombotic complications, & are associated with the use of NSAIDS. Other clinical manifestations include vasomotor disturbances such as headaches, transient neurologic or ocular symptoms, distal paresthesias, or erythromelalgia & pruritus after bathing. In addition, transformation into myeloid metaplasia occurs in 10%-30% of patients observed for 10-25 years, & there is a risk of transformation into leukemia.
All patients with polycythemia vera should be treated with phlebotomy to maintain a hematocrit of <45% in men & 42% in women. To balance the risk of thrombosis associated with phlebotomy with the potential risk of acute leukemia associated with hydroxyurea, phlebotomy should be supplemented with hydroxyurea in patients who are at high risk of thrombosis.
Low dose aspirin may be beneficial in some patients. However, higher doses of apirin are associated with increased bleeding in PV patients.
Progression to leukemia
This occurs in <5% of patients who are treated with phlebotomy alone. Note that this treatment has extended the median survival in patients with polycythemia vera to longer than 12 years!
Thrombosis & Bleeding:
In addition to advanced age & a history of thrombosis, treatment with phlebotomy alone has been associated with an increased risk of thrombosis. In a nonrandomized study, treatment with hydroxyurea was associated with lower incidences of both early thrombosis & acute leukemia (about 6% after a median follow-up of 8.6 years) (Fruchtman SM et al. Semin Hematol. 1997;34:17-23). The use of high doses of aspirin (300 mg TID) in combination with dipyridamole (75 mg TID) did not alter the risk of thrombosis but increased the risk of GI bleeding ( Berk PD et al. Treatment of polycythemia vera: a summary of clinical trials conducted by the Polycythemia Vera Study Group. Wasserman LR, Berk PD, Berlin NI, eds. Polycythemia Vera and the Myeloproliferative Disorders. Philadelphia: WB Saunders; 1995:166-194). More recent studies have suggested that the risk of bleeding is decreased with lower doses of aspirin (40 mg QD) (Gruppo Italiano Studio Policitemia (GISP). Low-dose aspirin in polycythaemia vera: a pilot study. Br J Haematol. 1997;97:453).
Thrombosis-directed risk stratification in polycythemia vera:
AGE<60 ; no history of thrombosis; no cardiovascular risk factors or extreme thrmobocytosis i.e. PLT>1.5 million/uL
AGE<60 ; no history of thrombosis; positive cardiovascular risk factors or extreme thrmobocytosis i.e. PLT>1.5 million/uL
AGE>60 &/or a history of thrombosis