Relationship between bone mineral density, trabecular bone score and uric acid level in postmenopausal women with rheumatoid arthritis

Background : uric acid (UA) is the end product of purine metabolism in humans. UA is considered as an antioxidant that prevents the negative effects of oxidative stress associated with aging and metabolic diseases. Some studies have shown both positive and negative associations between UA and bone mineral density (BMD) and its relationship with the trabecular bone score (TBS) is not fully understood. Aim : to determine the relationship of BMD and TBS with UA level in postmenopausal women with rheumatoid arthritis (RA). Materials and methods : the cross-sectional study included 140 postmenopausal women (median age 65.0 [59.5; 70.0] years) with a reliable diagnosis of RA. A unified questionnaire survey was conducted, a laboratory examination and dual-energy X-ray absorptiometry of femur and lumbar spine (L1-L4) with determination of TBS were performed. Results : in the examined group, degraded microarchitecture was detected in 40.7% of patients, and the mean UA level was 273.9±73.7 mmol/L. Correlation analysis revealed a positive association between UA level and BMD of L1-L4 (r=0.025, p=0.003), total hip (TH) (r=0.23, p=0.007) and femoral neck (FN) (r=0,15, p=0,045) and a negative association with TBS (r=-0.18, p=0.035). Multiple linear regression revealed a significant positive association between BMD L1-L4 and TH with UA and body mass index (BMI), a negative association of BMD TH and TBS with age and UA level with TBS, while BMD FN was negatively associated with age and positively associated with BMI and calcium intake, but no relationship has been identified with UA. Conclusion : our study showed an independent multidirectional relationship of UA level with BMD and TBS in postmenopausal women with RA: positive — with BMD L1-L4 and TH, negative — with TBS.