Higher serum uric acid levels are associated with reduced risk of hip osteoporosis in postmenopausal women with rheumatoid arthritis

Although the positive correlation between serum uric acid (UA) levels and bone mineral density (BMD) has been reported in the general population, there are little data regarding the effect of serum UA levels on bone loss in patients with rheumatoid arthritis (RA). We investigated whether increased serum UA levels were associated with a reduced risk of osteoporosis in postmenopausal women with RA. In this retrospective cross-sectional study, 447 postmenopausal female patients with RA and 200 age-matched, postmenopausal healthy controls underwent BMD examination by dual energy x-ray absorptiometry and serum UA levels measurement. Osteoporosis was diagnosed when the T-score was <-2.5. The median UA level in postmenopausal RA patients was found to be significantly lower than that in the healthy women (4 vs 4.1 mg/dL, P=.012) and the frequency of osteoporosis incidence in the lumbar spine, hip, and either site in RA patients was 25.5%, 15.9%, and 32.5%, respectively; the values were significantly higher than those of the controls. After adjusting for confounding factors, a significantly lower risk for osteoporosis of the hip in RA patients was observed within the highest quartile (odds ratio [OR]= 0.37, 95% confidence interval [CI]= 0.16-0.72, P=.021) and the second highest quartile (OR= 0.44, 95% CI= 0.2-0.95, P=.038) of serum UA levels as compared with the lowest quartile, but this association was not found to be consistent with respect to the lumbar spine. Serum UA levels also showed an independently positive correlation with femoral neck BMD (beta= 0.0104, P=.01) and total hip BMD (beta= 0.0102, P=.017), but not with lumbar BMD. Our data suggest that UA may exert a protective effect on bone loss in RA, especially in the hip.