Serial measurements of body composition and total body mineral content in dialysis and nondialysis patients with renal failure.

Thirty-two patients with chronic renal failure, and 68 patients on maintenance hemodialysis underwent serial total body neutron activation over periods of time ranging from 23 to 159 months. Measurements of total body potassium (TBK), total body sodium (TBNa), total body calcium (TBCa), total body phosphorus (TBPhos), and total body chloride (TBC1) were performed. The results were normalized by lean body mass (LBM) or kilogram body weight (BW). The TBNa/LBM and TBC1/BW decreased during the first 36 months of measurements in the dialysis males, while there was no change in the nondialysis males. The TBNa/LBM, TBC1/LBM and TBC1/BW decreased during the first 36 months of monitoring the dialysis females, while a decrease in the LBM was the only change in the nondialysis females. In patients with an increasing K ratio (observed/predicted TBK), the TBNa/LBM and TBCa/LBM decreased and the LBM/BW increased. Similarly, in patients with an increasing Ca ratio (observed/predicted TBCa), the TBCa/LBM and TBPhos increased. The increasing K ratio in dialysis patients with a decreasing TBNa/LBM probably represents an improvement in nutritional status. The increasing TBPhos in dialysis patients with an increasing Ca ratio may represent an increase in skeletal tissue and/or soft tissue calcification. In dialysis females, the total body nitrogen is not different from controls. The total body fat, as a percentage of body weight, is greater in dialysis patients than in controls.