Bone metabolism and histomorphometric changes in rheumatoid arthritis

OBJECTIVE: We studied bone metabolism and histomorphometry in 66 patients with rheumatoid arthritis. METHODS: Cross-sectional study. RESULTS: BMD at the forearm but not at the lumbar spine was decreased. Age. body mass index and fibrinogen correlated significantly with decreased BMD, whereas age and disease duration were predictors of vertebral fractures. Biochemical parameters were normal but 25 vitamin D levels were markedly reduced. There were significant decreases in bone volume, mean wall thickness, mineral apposition rate (with highly prolonged mineralisation lag time), number of osteoclasts, and osteoclast surface, and increases in resorption surfaces. Mean plate trabecular separation and density were also deeply affected. CONCLUSIONS: Patients with rheumatoid arthritis showed a reduced bone volume and decreased bone turnover, which is further aggravated by microarchitectural deterioration stressing the severe osteoporosis associated with the disease. These findings are consistent with the effect of hypovitaminosis D and low values of vitamin D in serum.