Bone mineral density and biochemical markers of bone metabolism in late onset rheumatoid arthritis and polymyalgia rheumatica--a prospective study on the influence of glucocorticoid therapy.

In the present prospective study, bone metabolism was examined in 51 patients at the time of diagnosis and 6-7 months later: 29 patients had definitive diagnosis of late onset rheumatoid arthritis (LORA) and 22 patients had polymyalgia rheumatica (PMR). At the time of diagnosis, the patients had not received any medication; during the 6-7 months of follow-up they were treated with corticosteroids and nonsteroidal-antirheumatic drugs (NSAIDs). Serum levels of osteocalcin, alkaline phosphatase and ostase, as markers for bone formation, were tested. Bone density was examined by dual x-ray absorption (DEXA) of the lumbar spine and the left ward triangle. At the time of diagnosis, no signs of bone alterations were seen. After 6-7 months, abnormal values of the serum parameters and bone mineral density were found in 16/51 patients (31%): 10/29 patients with LORA and 6/22 with PMR. Thus, our findings suggest that an alteration of bone metabolism could be observed in a minority of patients during the first few months of glucocorticoid medication, but in the majority of patients an osteoprotective effect seems to be worth discussing. The results suggest from a prophylactic and therapeutic point of view that an additional disease-modifying antirheumatic medication should be considered in the early stages of therapy to reduce the osteoporotic risk of a longterm corticoid therapy.