Severe Hypercalcemia due to Hypervitaminosis D in a Breastfed Infant

• Published in: JCEM case reports Vol. 1; no. 3; p. luad049
• Main Authors: Barzilay, Julie R, Kreienkamp, Raymond J, Gordon, Rebecca J
• Format: Report
• Language: English
• Published: 01.05.2023
• ISSN: 2755-1520
• DOI: 10.1210/jcemcr/luad049

Vitamin D is one of the most commonly recommended dietary supplements and is often the first medication ever prescribed in infancy. However, with the variety of concentrations available, including many over-the-counter formulations, dosing errors can easily occur. We present a case of a breastfed infant with a calcium level greater than 23 mg/dL (5.75 mmol/L), whose severe hypercalcemia was due to hypervitaminosis D from accidentally overdosed vitamin D supplementation. We consider the differential diagnosis for her presentation and review the interventions required for treatment of her hypercalcemia. Notably, we reinforce the importance of carefully reviewing dosing of vitamin D supplementation with families. We also discuss the management of hypercalcemia, including the role of fluids, diuretics, and glucocorticoids, as well as the long-term sequalae of severe hypercalcemia.