Kinetic studies on the serum 1, 25-dihydroxy vitamin D₃ and intact parathyroid hormone (PTH) levels in non-dialyzed, renal failure patients without diabetes mellitus

Abstract

Chronic renal failure is usually associated with disorders in Ca and P metabolism and secondary hyperparathyroidism as well as abnormalities in serum 1, 25-dihydroxyvitamin D₃ (1, 25VD₃) levels. We studied these correlations by regression analysis using mathematical models. The following regression equations were obtained: P=2.463+0.025urea+0.005iPTH, r²=0.909 Ca=9.785-0.012urea-0.002iPTH, r²=0.783 Ca×P=29.589+0.144urea+0.009iPTH, r²=0.648 iPTH=-190.06+69.07P-0.005CCr, r²=0.797 1, 25VD₃=16.99-1.12P+0.277CCr, r²=0.544 iPTH: intact parathyroid hormone (pg/ml);
CCr: creatinine clearance (l/day); P: serum phosphorus (mg/dl). The probability and accuracy of these models were confirmed by the one-way analysis of variance method. Our regression models showed that both the increased iPTH levels and disorders in 1, 25VD₃ levels in renal failure patients depend mainly on renal dysfunction and disorders in Ca and P levels. However, the changes in serum iPTH and 1, 25VD₃ levels were found to be independent of each other.