Normal calcitonin stimulation of serum calcitriol in patients with X-linked hypophosphatemic rickets

Michael J. Econs, Bruce Lobaugh, Marc K. Drezner

Research output: Contribution to journalArticle

18 Scopus citations


Patients with X-linked hypophosphatemic rickets (XLH) have normal or low calcitriol concentrations despite manifesting hypophosphatemia, a known stimulus of 25-hydroxyvitamin D-1 α-hydroxylase activity. In accord, administration of pharmacological doses of PTH results in a markedly blunted stimulation of calcitriol levels. In the murine homolog of the human disorder, the Hyp mouse, regulation of 25-hydroxyvitamin D-1 α-hydroxylase activity is defective in response to hypophosphatemia and PTH administration, but not in response to calcitonin administration. In the current study we administered calcitonin to controls and patients with XLH to test the hypothesis that calcitonin-stimulatable 25-hydroxyvitamin D-1 α-hydroxylase activity is normal in patients with XLH. We found that calcitriol concentrations increased in both groups to a similar degree (78.5 ± 20.9 pmol/L in patients and 49.9 ± 19.7 pmol/L in controls) and with a similar time course. Our results indicate that the complex and incomplete defect in the regulation of 25-hydroxyvitamin D-1 α-hydroxylase observed in Hyp mice also exists in humans.

Original languageEnglish (US)
Pages (from-to)408-411
Number of pages4
JournalJournal of Clinical Endocrinology and Metabolism
Issue number2
StatePublished - Aug 1992
Externally publishedYes


ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Biochemistry
  • Endocrinology
  • Clinical Biochemistry
  • Biochemistry, medical

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