The long-term skeletal retention and recirculation of 85Sr in man.

Abstract

The retention of85Sr for periods up to 150 days has been followed in 8 patients with osteoporosis, 2 patients with Paget's disease and 2 patients with chronic renal failure. The rate of decrease of whole body retention of isotope does not represent the rate of loss from the skeleton, as isotope returning from bone goes into a rapidly exchanging pool (R.E.P.) composed of E.C.F. soft tissue and bone, and from the pool is in part lost in urine, faeces and sweat, and in part returns to bone. We have determined the rate of loss of isotope from bone into the R.E.P. before recycling occurs. This rate of loss (γ) was found to be greater in Paget's disease than in osteoporosis, and in chronic renal failure, the last two being nearly equal. By applying our calculation to the data ofAdams andCarr (1965), we have found that in microphthalmic mice, which have very low rates of bone destruction (Gruneberg, 1963, 1948), the rate of return of isotope was in fact greater than in normal mice. This supports our previous conclusions that the rate of loss of85Sr is very largely due to heterionic exchange and not to resorption of labelled bone.