Primary Hyperparathyroidism in Pregnancy: Management and Diagnostic Pearls

Primary hyperparathyroidism in pregnancy is rare, representing <1% of cases, but carries substantial maternal and fetal risks, including nephrolithiasis, pancreatitis, pre-eclampsia, miscarriage, and neonatal hypocalcemia. Diagnosis is obscured by physiologic reductions in calcium and limited imaging options. The objective of this report is to describe 2 cases of primary hyperparathyroidism in pregnancy where unique imaging modalities were utilized.

A 36-year-old G3P2 female presented in the first trimester with nausea, fatigue, hypercalcemia (11.1 mg/dL; reference 8.5-10.5), and hyperparathyroidism (108 pg/mL; reference 19-88). Biplanar ultrasound and 4D CT of the thyroid and parathyroid glands were unremarkable. Management included oral hydration and parathyroidectomy at 22 weeks, with normalization of calcium and parathyroid hormone postoperatively.A 24-year-old G1P0 female presented in the first trimester with abdominal pain, hypercalcemia (12.2 mg/dL), and high-normal parathyroid hormone (70.5 pg/mL). Ultrasound of the thyroid/parathyroid glands was nondiagnostic and MRI suggested a lesion along the posterior-inferior aspect of the left thyroid lobe. Management included intravenous hydration and resection of a parathyroid adenoma at 23 weeks. Calcium and parathyroid hormone normalized postoperatively, and delivery was uncomplicated.

Primary hyperparathyroidism in pregnancy is difficult to diagnose due to hemodilution, hypoalbuminemia, and increased renal calcium excretion, lowering measured serum calcium. Treatment options are limited and expedited as standard medications lack safety data and serious complications are possible. Hydration provides temporary stabilization, while second-trimester surgery is the definitive treatment.

These cases highlight the importance of clinical suspicion, prudent imaging, and timely surgery to optimize maternal and fetal outcomes.