Abstract
Two commercially available PTH assay systems were compared in 443 maintenance hemodialysis patients (M/F=287/156) who had received dialysis for 7.2±4.7 (SD) years. Patients who had been parathyroidectomized were excluded. There was a positive correlation between predialysis serum intact PTH levels (I-PTH) and C-terminal PTH levels (C-PTH), but the correlation was relatively low, at 0.78. A significant negative correlation was observed between I-PTH and serum total calcium concentrations (r=-0.36, p<0.0001), but there was no correlation between C-PTH and calcium levels (r=-0.05, n. s.). Both PTH levels correlated positively with the duration of dialysis, and C-PTH had a higher correlation coefficient (r=0.20, p<0.0001) than I-PTH (r=0.11, p=0.025), probably because C-terminal fragments accumulate with the decrease in residual renal function during the course of dialysis. These results suggest that measurement of I-PTH is preferable to C-PTH for estimating parathyroid hormone secretion in maintenance hemodialysis patients.
