Abnormal vitamin B6 status is associated with severity of symptoms in patients with rheumatoid arthritis

Purpose Patients with rheumatoid arthritis have low plasma vitamin B6 levels and elevated plasma homocysteine responses to a methionine load. We examined whether these abnormalities are associated with clinical and biochemical indicators of disease status. Methods We performed a cross-sectional study in 37 patients who met the American College of Rheumatology criteria for rheumatoid arthritis. Vitamin B6 status was assessed by the plasma pyridoxal 5′-phosphate level and with the homocysteine response to a methionine load test. Clinical disease activity was assessed by joint counts, the Health Assessment Questionnaire disability score, and biochemical markers of the acute phase response. Results Plasma pyridoxal 5′-phosphate levels were inversely correlated with the erythrocyte sedimentation rate (r = −0.37, P = 0.02), C-reactive protein level (r = −0.52, P = 0.002), disability score (r = −0.37, P = 0.02), morning stiffness (r = −0.38, P = 0.02), and degree of pain (r = −0.33, P = 0.04). The increase in homocysteine levels after a methionine load correlated with the erythrocyte sedimentation rate (r = 0.39, P = 0.02), C-reactive protein level (r = 0.37, P = 0.03), disability score (r = 0.37, P = 0.04), degree of pain (r = 0.38, P = 0.02) and fatigue (r = 0.42, P = 0.01), number of painful joints (r = 0.43, P = 0.007), and number of swollen joints (r = 0.32, P = 0.05). Conclusion Markers of vitamin B6 status are associated with disease activity and severity, synovial burden, and pain in patients with rheumatoid arthritis, raising the possibility that impaired vitamin B6 status in these patients is a result of inflammation.