Recurrent hypocalcaemia in an infant with primary hypoparathyroidism due to maternal and infant vitamin D deficiency

Primary hypoparathyroidism is a rare disorder characterised by hypocalcaemia due to insufficient secretion of parathyroid hormone, which plays a critical role in calcium homeostasis. We report a case of an infant with primary hypoparathyroidism associated with 22q11.2 deletion syndrome who developed recurrent hypocalcaemia despite treatment with active vitamin D analogues. Further evaluation revealed severe vitamin D deficiency in both the infant and her mother, as well as low calcium concentrations in breast milk. The mother adhered to a vegetarian diet and practised exclusive breastfeeding, which likely led to insufficient calcium and vitamin D intake in the infant. The recurrent hypocalcaemia was attributed to the combination of impaired parathyroid hormone response and inadequate calcium intake. Vitamin D deficiency was treated in both the mother and the infant, resulting in the resolution of recurrent hypocalcaemia in the infant. This case highlights the importance of comprehensive clinical and nutritional assessment in infants with primary hypoparathyroidism, particularly when symptoms recur despite appropriate initial therapy.