Infantile hypercalcaemia type 1: A vitamin D-mediated, under-recognised cause of hypercalcaemia

Ryizan Nizar (Lead Author), Nathan W. P. Cantley, Jonathan C. Y. Tang

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A 33-year-old gentleman of Egyptian heritage presented with a 21 years history of unexplained and recurrent hypercalcaemia, nephrolithiasis, nephrocalcinosis, and myocarditis. A similar history was also found in two first-degree relatives. Further investigation into the vitamin D metabolism pathway identified the biochemical hallmarks of infantile hypercalcaemia type 1 (IIH). A homozygous, likely pathogenic, variant in CYP24A1 was found on molecular genetic analysis confirming the diagnosis. Management now focuses on removing excess vitamin D from the metabolic pathway as well as reducing calcium intake to achieve serum-adjusted calcium to the middle of the reference range. If undiagnosed, IIH can cause serious renal complications and metabolic bone disease.

Original languageEnglish
Article number21-0058
JournalEndocrinology, Diabetes and Metabolism Case Reports
Issue number1
Early online date22 Sep 2021
Publication statusPublished - Sep 2021

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