Effect of single oral phosphate loading on vitamin D metabolites in normal subjects and in X-linked hypophosphatemic rickets

Bone Miner. 1989 Sep;7(2):159-69. doi: 10.1016/0169-6009(89)90073-1.

Abstract

There have been several reports that document abnormal vitamin D metabolism in X-linked hypophosphatemic rickets (XLH). Those reports indicate a blunted renal 25-hydroxyvitamin D-1 alpha-hydroxylase response to a potent stimulator, phosphorus restriction. We examined here its response to phosphate supplementation. Seven normal volunteers and 12 patients with XLH were submitted to single oral phosphate loading. This treatment produced a marked elevation of the serum phosphorus level, with a mild reduction in the serum calcium level. In normal subjects, although the concentrations of intact parathyroid hormone and mid-region parathyroid hormone were increased, with two peaks at 2 and 8 h after treatment, there were no significant changes in vitamin D metabolites including 25-hydroxyvitamin D (25(OH)D), 24,25-dihydroxyvitamin D (24,25(OH)2D) and 1,25-dihydroxyvitamin D (1,25(OH)2D). On the other hand, in the patients with XLH, the serum 1,25(OH)2D level increased from 23.4 +/- 12.0 (mean +/- SD) pg/ml to 44.3 +/- 33.6 pg/ml 6 h after ingestion without any significant change in 25(OH)D or 24,25(OH)2D.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • 24,25-Dihydroxyvitamin D 3 / blood
  • Administration, Oral
  • Adolescent
  • Adult
  • Calcifediol / blood
  • Calcitonin / blood
  • Calcitriol / blood
  • Child
  • Child, Preschool
  • Female
  • Humans
  • Hypophosphatemia, Familial / blood*
  • Hypophosphatemia, Familial / metabolism
  • Male
  • Middle Aged
  • Parathyroid Hormone / blood
  • Phosphates / administration & dosage*
  • Phosphates / blood
  • Phosphates / pharmacology
  • Rickets / blood*
  • Rickets / metabolism
  • Vitamin D / metabolism*

Substances

  • Parathyroid Hormone
  • Phosphates
  • Vitamin D
  • 24,25-Dihydroxyvitamin D 3
  • Calcitonin
  • Calcitriol
  • Calcifediol