Increased bone metabolism in rheumatoid arthritis as measured by the whole-body retention of 99Tcm methylene diphosphonate.

Bone metabolism in 21 patients with rheumatoid disease was investigated by measurement of the 24-hour whole body retention (WBR) of 99Tcm methylene diphosphonate (MDP) in parallel with clinical, radiological, and biochemical measurements (urinary excretion of hydroxyproline) of disease activity. Corticosteroid-treated patients of those with other forms of metabolic bone disease were excluded from the study. WBR was increased in the rheumatoid patients as compared with 21 age- and sex-matched controls (p less than 0.05), and there was a significant correlation in the rheumatoid group between WBR and urinary excretion of hydroxyproline (p less than 0.01) and between urinary excretion of hydroxyproline and an articular index (p less than 0.05) and global index (p less than 0.01) of disease activity. The increased WBR of the rheumatoid patients was not explicable by factors such as immobilisation, and the results are interpreted as reflecting an overall increase in bone metabolism which may occur in rheumatoid arthritis as part of the disease process.