title: Calcemic and phosphaturic response to parathyroid hormone in normal and chronically uremic dogs.
abstract: It is well established that the calcemic response to parathyroid hormone (PTH) is blunted in chronic uremia and is corrected partially by 1,25(OH)2D treatment. Recent evidence suggests that PTH(1-34) and not PTH(1-84) may be the actual calcemic fragment. Equivalent doses of both peptides were infused into five normal dogs (GFR = 51 ml/min) and eight dogs with a remnant kidney and chronic renal insufficiency (GFR = 15 ml/min). Both the calcemic and phosphaturic responses were studied. Remnant dogs had a blunted calcemic response to bPTH(1-84). The increase in fractional phosphate excretion was similar. In contrast, the calcemic response to bPTH(1-34) was equivalent in remnant and normal dogs. Treatment of uremic dogs with 400 ng 1,25(OH)2D daily for 3 days restored the effect of bPTH(1-84) on serum calcium and increased the control value for tubular phosphate reabsorption from 28 +/- 3 micrograms/ml GFR to 37 +/- 4 micrograms/ml GFR (P less than 0.01). These results suggest that there is an impaired conversion of PTH(1-84) to PTH(1-34) in chronic renal insufficiency and that 1,25 (OH)2D may be involved in metabolism of PTH(1-84). In addition, the effect of PTH on fractional phosphate excretion is not magnified in nonparathyroidectomized uremic dogs.
mesh_terms: D000818:Animals; D002117:Calcitriol / Q000378:metabolism / Q000627:therapeutic use; D002118:Calcium / Q000097:blood*; D004285:Dogs; D005260:Female; D005919:Glomerular Filtration Rate; D010281:Parathyroid Hormone / Q000378:metabolism / Q000494:pharmacology*; D010446:Peptide Fragments / Q000494:pharmacology; D010710:Phosphates / Q000097:blood*; D019379:Teriparatide; D014511:Uremia / Q000188:drug therapy* / Q000378:metabolism
chemical_list: D010281:Parathyroid Hormone; D010446:Peptide Fragments; D010710:Phosphates; D019379:Teriparatide; D002117:Calcitriol; D002118:Calcium