Abnormal homocysteine metabolism in rheumatoid arthritis

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Abstract
Objective. To assess total homocysteine (tHcy) metabolism in patients with rheumatoid arthritis (RA). Methods. Assessments were performed to determine the fasting levels of tHcy and the increase in tHcy in response to methionine (Met) challenge in blood samples from 28 patients with RA and 20 healthy age‐matched control subjects. Results. Fasting levels of tHcy were 33% higher in the RA patients than in the control subjects (mean ± SD 11.7 ± 1.5 nmoles/ml versus 8.8 ± 1.1 nmoles/ml; P < 0.01). Four hours after Met challenge, the increase in plasma tHcy levels (ΔtHcy) was higher in the RA patients (20.9 ± 10.4 nmoles/ml) than in the control subjects (15.5 ± 1.6 nmoles/ml) (P < 0.02). In a subgroup analysis, the ΔtHcy in patients taking methotrexate (12.9 ± 2.2 nmoles/ml) did not differ from that in the control group, while the ΔtHcy in patients not taking methotrexate (25.3 ± 1.7 nmoles/ml) was significantly higher (P < 0.0001). Conclusion. Elevated tHcy levels occur commonly in patients with RA, and may explain some of the increased cardiovascular mortality seen in such patients. Studies of the prevalence and mechanism of hyperhomocysteinemia in RA are warranted.