SUMMARY

In vivo neutron activation analysis was used to measure sequential changes in total body calcium in 14 unselected cases of chronic renal insufficiency. Creatinine clear-ance ranged from 6 to 43 ml/min but none of the patients required dialysis during the period of study. Patients were classified according to the dominant change occurring in iliac crest bone biopsies. Total body calcium fell in those patients with osteomalacia but this change could be reversed with pharmacological doses of vitamin D. In those with osteitis fibrosa total body calcium increased and the possible significance of this finding is discussed