Bone GLA protein (BGP) levels and bone turnover in rheumatoid arthritis.

Bone GLA protein (BGP) and other biochemical indices of bone turnover were measured in 42 female patients with rheumatoid arthritis (RA) and in a group of normal subjects matched for sex and age. Mean serum BGP concentrations were significantly higher in patients with active arthritis than in patients with mild activity (p less than 0.01) and controls (p less than 0.01). No significant difference was found in serum BGP levels and in other parameters of bone turnover when the patients were stratified according to functional class or duration of disease. There was a correlation between BGP and alkaline phosphatase levels only in RA patients with high activity of disease. Our data suggest an accelerated bone turnover in patients with active RA. We infer that in such patients the impairment of bone metabolism is a determinant of RA-associated osteopenia. Disease activity rather than functional impairment or duration of arthritis should be regarded as a factor in the bone loss of RA.