Age-related alterations in skeletal metabolism--24-hr whole-body retention of diphosphonate in 250 normal subjects: concise communication.

Twenty-four-hour measurements of whole-body retention (WBR) of Tc-99m diphosphonate (a sensitive measure of skeletal metabolism) have been obtained in 250 healthy volunteer subjects. WBR values were found to fall from the age of 20 yr until 35 yr and then in men to rise linearly thereafter. Women showed a similar pattern initially but there was a marked rise in WBR corresponding to the menopausal years. Our results lend support to the belief that skeletal metabolism increases with age. It is suggested that some imbalance must always exist between resorption and formation in bone, with net loss of bone mineral, and increasing levels of skeletal metabolism will exaggerate this imbalance and accelerate the rate of bone loss.