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[Dysregulation of plasma 1,25(OH)2D in calcium restriction in hypercalciuric children]

C Belon1, R Dumas, C Tau

  • 1Laboratoire de Biochimie I, Faculté de Pharmacie, Montpellier.

Archives Francaises De Pediatrie
|June 1, 1992
PubMed

Insights

Calcium restriction increases 1,25(OH)2D in normocalciuric children but not in hypercalciuric children. This suggests impaired dietary vitamin D regulation in hypercalciuric patients.

Area of Science:

  • Pediatric Nephrology
  • Endocrinology
  • Nutritional Science

Context:

  • The relationship between calcium intake and vitamin D metabolism in children with varying calcium excretion levels is not well understood.
  • Hypercalciuria, a condition of elevated urinary calcium, can be associated with kidney stones and other renal abnormalities.

Purpose:

  • To investigate the impact of dietary calcium restriction on plasma 1,25-dihydroxyvitamin D [1,25(OH)2D] levels in normocalciuric and hypercalciuric children.
  • To compare phosphate and calcium metabolism between these two groups under different dietary calcium conditions.

Summary:

  • Studies included 8 normocalciuric and 8 hypercalciuric children (ages 4-16) under normal calcium intake, calcium restriction, and calcium loading.
  • Hypercalciuric children exhibited higher urinary calcium, elevated plasma 1,25(OH)2D, and lower tubular reabsorption of phosphate (TmP) compared to controls.
  • While normocalciuric children showed increased 1,25(OH)2D after calcium restriction, hypercalciuric children did not, indicating a potential impairment in vitamin D regulation.

Impact:

  • Dietary calcium restriction influences 1,25(OH)2D levels in normocalciuric children through a mechanism independent of parathyroid hormone (PTH) and phosphorus.
  • Hypercalciuric children demonstrate an impaired ability to regulate renal vitamin D metabolism in response to dietary calcium changes.
  • Findings highlight potential differences in calcium and vitamin D homeostasis between normocalciuric and hypercalciuric pediatric populations.
Abstract

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