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

Abstract 

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.

Keywords:  Rheumatoid arthritis, Inflammation, Pyridoxal 5′-phosphate, Homocysteine, C-reactive protein, Erythrocyte sedimentation rate