Whole body retention of diphosphonate in rheumatoid arthritis

The skeletal metabolism of patients with rheumatoid arthritis (RA) osteoarthritis (OA) and ankylosing spondylitis (AS) has been assessed by 24-h whole body retention of 99mTc diphosphonate (WBR). Values for RA and AS patients were significantly elevated but those of OA patients were not when compared to age and sex matched controls (27.0 +/- 8.6 vs 20.5 +/- 1.8%; 24.8 +/- 5.4 vs 19.4 +/- 1.5% greater than and 21.4 +/- 4.1 vs 21.2 +/- 1.4%, respectively). The WBR of patients taking steroids was greatly elevated and RA inpatients had higher values than outpatients, but the increased WBR could not be correlated with disease activity. The increased WBR in RA may represent an indirect effect possibly related to immobility.