Infantile hpercalcaemia Type 1: a vitamin D-mediated, under-recognised cause of hypercalcaemia

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

Research output: Contribution to journalArticlepeer-review


A 33 year old gentleman of Egyptian heritage presented with a 21 year 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) [1]. 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
JournalEndocrinology, Diabetes and Metabolism Case Reports
Issue number1
Early online date22 Sep 2021
Publication statusPublished - Sep 2021

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