Markers of bone metabolism in postmenopausal women with rheumatoid arthritis

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Abstract
Objective. To investigate bone metabolism in postmenopausal women with rheumatoid arthritis (RA) treated with or not treated with corticosteroids, and the response to hormone replacement therapy (HRT). Methods. One hundred six RA patients were divided into those taking low‐dose steroids (RA+; n = 35) and those not (RA–; n = 71) and randomly allocated to receive HRT or calcium for 2 years. Bone formation markers included serum osteocalcin (OC) and bone‐specific alkaline phosphatase, and resorption markers included urinary deoxypyridinoline (DPyr) and CrossLaps (XL). Bone mineral density (BMD) was measured annually using dual x‐ray absorptiometry. Results. OC levels were significantly lower in both the RA+ and RA– groups compared with 112 healthy control subjects (P < 0.01 and P < 0.05, respectively), but were similar in the 2 RA groups. DPyr and XL levels were elevated in the RA+ group compared with the RA– group (P < 0.05) but were similar between the RA– group and controls. OC was negatively correlated with parameters of disease activity (P < 0.05). After HRT, XL excretion decreased significantly in the overall RA group. Three‐month changes in XL correlated with 2‐year changes in spinal BMD (P < 0.01). Conclusion. Bone metabolism may be uncoupled in chronic RA. Bone formation appears to be reduced, partly reflecting disease activity, whereas resorption increased only in steroid users. HRT reduces resorption in RA irrespective of steroid usage, emphasizing its value in the treatment of postmenopausal women with RA.