Behind the storm: A case of severe hypercalcemia due to an atypical parathyroid tumor during late pregnancy

A 37-year-old pregnant woman who developed life-threatening hypercalcemia and acute pancreatitis at 33 weeks of gestation. The patient was presented with premature contractions, altered mental status, and fetal distress, requiring emergency delivery. Initial laboratory findings revealed elevated calcium levels at 17.1 mg/dL and parathyroid hormone at 1194 pg/mL. Despite intense medical management including intravenous hydration, zoledronic acid, and dialysis, hypercalcemia persisted. Imaging studies identified multiple parathyroid nodules and osteolytic bone lesions. The patient underwent a successful parathyroidectomy with removal of a 3 cm adenoma. Histopathological analysis revealed an atypical parathyroid tumor with trabecular architecture, preserved parafibromin expression, and low Ki-67 index, indicating low malignancy risk. Postoperatively, parathyroid hormone levels dropped dramatically from 1194 pg/mL to less than 4 pg/mL within 24 hours, though subsequently rose to 189 pg/mL during follow-up. At three months of postpartum, calcium levels remained normal with supplementation. This case highlights the diagnostic challenges of hyperparathyroidism during pregnancy and emphasizes the importance of early recognition, multidisciplinary management, and long-term surveillance for atypical parathyroid lesions.