Whole body retention of 99mTc-diphosphonate. Relation to biochemical indices of bone turnover and to total body calcium.

Whole body retention (WBR) and urinary excretion (UE) of 99mTc-diphosphonate were determined in 161 healthy adults and the results were compared to accepted biochemical markers of bone turnover. WBR was corrected for total body bone mineral (TBBM) and UE for forearm bone mineral content (BMC). Both uncorrected and corrected retention measurements were highly significantly correlated to the biochemical markers (P less than 0.001), but the r values were low (0.22-0.64). All bone turnover variables demonstrated considerably higher levels of bone turnover in postmenopausal women than in premenopausal women (P less than 0.001), whereas the variables were unchanged with age in men. The correction of WBR for TBBM and UE for BMC increased the validity of the retention methods and the two calculations gave exactly the same results on a group basis, both demonstrating significantly higher bone turnover in women than in men in each age group (P less than 0.05-P less than 0.001). All the turnover variables were measured in a group of perimenopausal women (n = 33). The data clearly demonstrated that bone turnover is menopause dependent, whereas age in itself is of minor significance.