Background Hyperhomocysteinaemia is a well-known risk factor for cardiovascular diseases. Patients with severe chronic plaque psoriasis have a higher risk of death due to arterial and/or venous thrombosis.
Objectives To investigate the relationship among plasma homocysteine and folate levels and severity of chronic plaque psoriasis in a selected cohort of patients with psoriasis without known risk factors for acquired hyperhomocysteinaemia.
Methods We performed a case–control study in 40 patients with chronic plaque psoriasis and 30 age- and sex-matched healthy controls. Cases and controls were selected excluding individuals with conditions or diseases associated with acquired hyperhomocysteinaemia, and were also asked to stop alcohol and coffee consumption for 1 week before blood sampling. The plasma levels of homocysteine and folic acid were measured and were correlated with the severity of psoriasis (Psoriasis Area and Severity Index, PASI).
Results Patients with psoriasis had plasma homocysteine levels higher than controls (mean ± SD 16·0 ± 5·6 vs. 10·4 ± 4·7 μmol L−1; P < 0·001). Conversely, folic acid levels were lower in patients with psoriasis compared with controls (mean ± SD 3·6 ± 1·7 vs. 6·5 ± 1·7 nmol L−1; P < 0·001). Plasma homocysteine levels in patients with psoriasis correlated directly with disease severity (PASI) and inversely with folic acid levels. Plasma folic acid levels were inversely correlated with the PASI. No abnormalities of plasma vitamin B6 and B12 were found.
Conclusions Patients with psoriasis may have a tendency to hyperhomocysteinaemia, which may predispose to higher cardiovascular risk. Dietary modification of this risk factor appears relevant to the global management of patients with moderate to severe psoriasis.