Homocysteine levels in polycythaemia vera and essential thrombocythaemia.

Patients with polycythaemia vera (PV) or essential thrombocythaemia (ET) have an increased risk of arterial and venous thromboembolic complications. Since hyperhomocysteinaemia (HHC) is a risk factor for vascular disease, we investigated the frequency of HHC in these disorders and analysed a possible association of elevated plasma homocysteine levels with vascular complications. In the cohort of 134 patients from Vienna (69 female, 65 male, median age 65.5 years, range 21-91 years) with PV (n = 74) or ET (n = 60), plasma homocysteine levels were significantly higher compared to 134 healthy controls. Median homocysteine level was 12.3 micromol/l (range 3.5-48.4 micromol/l) in patients with PV or ET and 8.9 micromol/l (range 4.8-30.5 micromol/l) in normal controls (P < 0. 0001). In addition to the 134 patients from Vienna, 48 patients (28 female, 20 male; median age 66.5 years, range 24-82) from Vicenza with PV (n = 25) or ET (n = 23) were included to evaluate the impact of HHC on the risk of thrombosis. Of 59 patients with HHC (44 from Vienna and 15 from Vicenza) 18 (31%) had a history of arterial and 10 (17%) of venous thrombosis. Of 123 patients with normal homocysteine levels, 30 (24%) had arterial and 16 (13%) had venous thromboses. The difference between the two groups was statistically not significant. Even though mild to moderate HHC occurred in a larger number of patients with PV or ET and thrombosis, it can presently not be regarded as an additional risk factor for thrombosis.