Abnormal 99mTechnetium-tin-pyrophosphate bone scans in chronic renal failure

A high incidence of abnormal 99mTechnetium-tin-pyrophosphate (99mTcPPi) is reported in a population of chronic renal failure patients. Using the 5 hour bone to soft tissue ratio as a quantitative index of increased uptake, 78% of 45 long-term dialysis patients and a similar proportion of non-dialyzed chronic renal failure patients were found to have increased uptakes. In animal studies using a uremic model, similar increased uptakes of 99mTcPPi was found with evidence of increased vascularity as reflected by red cell or plasma volumes in the bone or by the uptake of concomitantly administered 45Ca. The evidence suggests that the abnormal bone scans reflect abnormalities in collagen metabolism that occurs in the uremic state and that 99mTcPPi scans are useful in the diagnosis and management of renal osteodystrophy.