Is bone turnover a determinant of bone mass in rheumatoid arthritis?

OBJECTIVE

To study the relationship between bone turnover markers and bone mineral density in patients with rheumatoid arthritis.

METHODS

We studied 54 patients, 24 of whom were receiving low dose steroids, and compared them to 54 age and sex matched controls.

RESULTS

An 8.2% decrease of femoral neck bone mineral density (BMD) was found in patients not taking steroids compared with controls (confidence interval 1.2-15.3%). Serum markers of bone turnover -- namely, procollagen type I C-terminal propeptide (PICP) and procollagen type I N-terminal propeptide (PINP), which reflect bone formation, and procollagen type I C-terminal telopeptide, which reflects bone resorption -- were significantly increased compared with controls (p < 0.05, p < 0.01, p < 0.01, respectively). Both PINP levels and PICP levels were correlated with the femoral neck BMD as well as osteocalcin levels: R = -0.32 (p < 0.05), R = -0.29 (p < 0.05), and R = -0.42 (p < 0.01), respectively. The best independent predictors of bone mass (stepwise multiple regression analysis) at the femoral neck were steroid use, osteocalcin levels, age, height, the presence of rheumatoid factor, and the Health Assessment Questionnaire score, which explained 61.6% of the variance in femoral neck BMD.

CONCLUSION

Elderly patients with RA using steroids with severe disease and high levels of osteocalcin have marked osteoporosis at the hip.