title: Acute oral calcium load decreases parathyroid secretion and suppresses tubular phosphate loss in long-term renal transplant recipients.
abstract: Persistent hyperparathyroidism and impaired tubular reabsorption of phosphate (P) are common after kidney transplantation. In order to assess the suppressibility of these abnormalities, we studied the effects of a single oral calcium (Ca) load (1 g) in 7 healthy subjects (HS) and in 14 normocalcemic long-term renal transplant recipients with good renal function (RT). In HS and RT, serum and urinary Ca were similar at baseline, and increased (p < 0.001) to the same extent after Ca ingestion. Serum parathyroid hormone (PTH) and nephrogenic cAMP (NcAMP) levels were higher at baseline in RT than HS (mean +/- SEM; respectively, PTH 7.8 +/- 0.8 vs. 3.5 +/- 0.6 pmol/l, p < 0.001, and NcAMP 24.8 +/- 2.3 vs. 13.9 +/- 2.3 nmol/l GFR, p < 0.01). After Ca, PTH (p < 0.001) and NcAMP (p < 0.01) decreased markedly in both RT and HS. Maximal changes in PTH and NcAMP were larger in RT than HS (PTH - 3.3 +/- 0.4 vs. -2.1 +/- 0.03 pmol/l, p < 0.01, and NcAMP -18.2 +/- 3.3 vs. -8.1 +/- 2.6 nmol/l GFR, p < 0.05). Although PTH levels remained significantly higher in RT than HS from baseline to the end of the study (p < 0.001), PTH decreased to the normal range in RT after Ca load. Moreover, NcAMP reached similar values in RT and HS after Ca (16.0 +/- 3.3 vs. 13.2 +/- 2.8 nmol/l GFR at the end of the survey, NS).(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Explorations Fonctionnelles Rńales Métaboliques et Endocriniennes, Centre Hospitalier Universitaire, Bescançon, France.
authors.forename: G
authors.initials: G
authors.lastname: Dumoulin
authors.forename: B
authors.initials: B
authors.lastname: Hory
authors.forename: N U
authors.initials: NU
authors.lastname: Nguyen
authors.forename: M T
authors.initials: MT
authors.lastname: Henriet
authors.forename: C
authors.initials: C
authors.lastname: Bresson
authors.forename: J
authors.initials: J
authors.lastname: Regnard
authors.forename: Y
authors.initials: Y
authors.lastname: Saint-Hillier
mesh_terms: D000284:Administration, Oral; D000328:Adult; D002118:Calcium / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D016022:Case-Control Studies; D000242:Cyclic AMP / Q000378:metabolism; D005260:Female; D006801:Humans; D006962:Hyperparathyroidism, Secondary / Q000517:prevention & control; D016030:Kidney Transplantation / Q000502:physiology*; D007684:Kidney Tubules / Q000378:metabolism*; D008297:Male; D010281:Parathyroid Hormone / Q000378:metabolism* / Q000502:physiology; D010710:Phosphates / Q000378:metabolism*; D011183:Postoperative Complications / Q000517:prevention & control; D013997:Time Factors
chemical_list: D010281:Parathyroid Hormone; D010710:Phosphates; D000242:Cyclic AMP; D002118:Calcium