Hypophosphatemia with elevations in serum fibroblast growth factor 23 in a child with Jansen's metaphyseal chondrodysplasia

Whitney W. Brown, Harald Jüppner, Craig B. Langman, Heather Price, Emily G. Farrow, Kenneth E. White, Kenneth L. McCormick

Research output: Contribution to journalArticle

75 Scopus citations

Abstract

Context: Previous studies have suggested a regulatory relationship between serum phosphorus, vitamin D, and fibroblast growth factor 23 (FGF23), a hormone that promotes renal excretion of phosphate. Despite these associations, the identity of the primary regulator of serum FGF23 is unresolved. Jansen's metaphyseal chondrodysplasia is a rare autosomal dominant disorder associated with short-limbed dwarfism and other characteristic skeletal abnormalities. This condition is caused by mutations in the PTH/PTHrP receptor that result in ligand-independent cAMP accumulation, thus rendering the receptor constitutively active. These patients typically exhibit asymptomatic hypercalcemia and hypophosphatemia despite low or undetectable serum levels of PTH and PTHrP. Evidence Acquisition: A literature search revealed that serum FGF23 levels had not been studied in patients with Jansen's syndrome, a disorder in which the biochemical features present a unique opportunity to study the possible relationship between FGF23 and calcium-phosphorus-vitamin D metabolism. A case of Jansen's syndrome is presented in which serum FGF23 concentrations, along with serum phosphorus and 1,25(OH)2 vitamin D levels, were measured and compared with those of age-matched controls. Evidence Synthesis: Serum FGF23 concentrations in the patient with Jansen's syndrome were found to be markedly and persistently elevated, compared with values in healthy, age-matched controls, despite hypophosphatemia and normal 1,25(OH)2 vitamin D levels. Conclusion: Together, our findings indicate that serum FGF23 could be governed by factor(s) other than serum phosphorus, potentially by activation of the PTH/PTHrP receptor in bone.

Original languageEnglish (US)
Pages (from-to)17-20
Number of pages4
JournalJournal of Clinical Endocrinology and Metabolism
Volume94
Issue number1
DOIs
StatePublished - Jan 2009

ASJC Scopus subject areas

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

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