Objectives: Vitamin D (VD) has multiple physiological function 
including bone-mineral metabolism and musculo-skeletal effects. 
The purpose of this study is to disclose actual circumstances of 
VD contentment and characteristics in patients with Rheumatoid 
Arthritis (RA). 
Methods: Serum VD levels of 132 outpatients with RA 
consecutively selected in our hospital were estimated. The 
relationship between serum VD levels and various clinical indices 
was investigated.
Results: Mean serum concentration of 25-hydroxyvitamin D3
 
(25OHD) in total subjects was 18.1ng/ml, which was regarded as 
apparent VD deficiency. Importantly, 60% of the subjects showed 
less than 20ng/ml, and only 5% exceeded 30ng/ml which fulfilled 
sufficient VD level. In contrast, mean serum 1α, 25-dihydroxyvitamin 
D3
 level was 37.9 pg/ml, which was within the normal reference 
value. Disease activity and various serum chemistry data were not 
related to the VD levels. Instead, there was a tendency that higher 
Steinbrocker’s functional class was associated with lower serum 
25OHD level. 

Conclusion: From these results, we concluded that frequency 
of VD deficiency in RA patients is high and it is supposed that low 
physical activity is closely related to VD deficiency. Appropriate VD 
supplementation should be considered a part of comprehensive 
management of RA patients.
Keywords: Rheumatoid arthritis; Vitamin D deficiency; 
25-hydroxyvitamin D.