Neonatal Severe Primary Hyperparathyroidism: A Case Report on the Successful Management of Hypercalcemia with Phosphorus Supplementation

Neonatal Severe Primary Hyperparathyroidism (NSHPT) is a rare autosomal recessive disorder caused by inactivating mutations in the calcium-sensing receptor (CaSR) gene, leading to severe hypercalcemia and elevated parathyroid hormone levels. We report the case of a 7-day-old girl who presented with hypercalcemic crisis and was treated with hyperhydration, bisphosphonates, and phosphorus supplementation. Despite initial management, cinacalcet showed limited efficacy, suggesting a homozygous phenotype. Long-term management remains challenging, with surgery being the ultimate solution. Genetic analysis is crucial to guide treatment strategies.