Serum Osteocalcin Levels in Premenopausal Rheumatoid Arthritis Patients

The objective of this study was to assess the occurrence of generalized bone loss in rheumatoid arthritis (RA) patients and to evaluate the factors influencing bone loss, in particular, the usefulness of bone turnover markers. Twenty-five premenopausal patients (mean age, 40 x 5 years) with active RA were compared with 27 age-matched premenopausal patients with RA but without active disease and 30 age-matched healthy premenopausal controls. Serum concentrations of osteocalcin, intact parathyroid hormone (PTH), spot urine concentrations of crosslinked N-telopeptidases of type 1 collagen (NTX), and deoxypyridinoline (DPD) were detected by ELISA and radioimmunoassay. Serum osteocalcin levels were found to be significantly lower (p < 0.001) in patients with active RA compared with patients without active RA and controls. Similarly, serum intact PTH was significantly lower (p < 0.01) in patients with active RA than in patients with RA without active disease and controls. Spot urine concentrations of NTX and DPD were significantly higher (p < 0.01) in active RA patients than in patients with nonactive RA and controls. Positive correlations between osteocalcin and marker of disease activity were found to be significant (p < 0.01). There were no significant correlations between serum intact PTH, urine concentrations of NTX and DPD, and markers of inflammation. This study suggests that generalized bone loss occurs in active RA and is characterized by an evident bone resorption correlated with the high levels of inflammation.