Rheumatoid arthritis (RA) is a chronic inflammatory condition that can be associated with abnormal bone turnover and hence osteoporosis. Osteocalcin (OC) levels are increased in conditions with high bone turnover, including high RA disease activity. Thus, OC levels could possibly be used as a marker to assess bone health and disease activity in RA patients. As there have been no previous studies looking at serum OC levels in Malaysian RA patients, this study was performed to examine possible correlations between OC, bone mineral density (BMD) and disease activity in this population. A cross-sectional study of 75 female RA patients and 29 healthy controls was performed. Serum OC was measured using a Quantikine® ELISA kit. Dualenergy x-ray absorptiometry (DXA) was used to assess BMD. Serum OC levels were not significantly different between RA patients (median 14.44 ng/mL, interquartile range [IQR 12.99]) compared to healthy controls (median 11.04 ng/mL IQR 12.29) (p=0.198). Serum OC increased with age (Spearman’s rho r=0.230, p=0.047). There was no significant correlation between serum OC and body mass index (BMI), menopause status, BMD, DAS28, swollen or tender joint counts. Overall, there were 11 (14.7%) patients with osteoporosis and 27 (36.0%) with osteopenia. Menopause status was significantly associated with BMD at all sites (lumbar spine p=0.002, femoral neck p=0.004, total hip p=0.002). Serum OC were similar in RA patients compared to healthy controls. In RA patients, serum OC did not correlate with RA disease activity or BMD. Menopause status remains an important influence on BMD. Thus, measuring serum OC levels in Malaysian RA patients was not useful in identifying those at risk of low BMD.
Study site: Rheumatology clinic, Hospital Tuanku Jaafar, Seremban, Negeri Sembilan, and Klinik Pakar Puchong, Kuala Lumpur, Malaysia