Whole-body retention (WBR) of 99mTc-methylene diphosphonate was measured in 15 control subjects and in 99 patients with various metabolic bone diseases (osteoporosis, Paget's disease of the bone, hyperparathyroidism). In all the subjects WBR was measured indirectly from urinary excretion and in 30 it was also measured directly using a simple detector. Mean WBR values did not differ between control subjects and osteoporotic patients, whereas patients with Paget's disease and patients with hyperparathyroidism had significantly higher mean WBR levels than the controls. However, overlapping of results among the groups was high, and consequently the diagnostic value in the individual patients was low. In the patients whose WBR levels were measured simultaneously by both the direct and the indirect urinary method, the results were essentially the same, provided urine losers were excluded. Comparison of the two detection methods showed that urine loss occurred frequently and this was probably partly responsible for the low diagnostic sensitivity of the WBR. When WBR was measured at different time intervals in untreated individuals, the values remained markedly constant. The method would probably be of value in monitoring treatments influencing bone turnover in metabolic bone diseases.
