Primary Hyperparathyroidism in Pregnancy Complicated by Severe Hypercalcemia and Variable Outcomes

Primary hyperparathyroidism (PHPT) is rare, occurring in 0.86% of the United States population. PHPT of pregnancy is rarer, occurring in one percent of pregnancies. Oftentimes, calcium is mildly elevated and does not result in maternal or fetal complications. However, when levels rise, serious issues can occur. These cases demonstrate various clinical courses in pregnant women with PHPT and severe hypercalcemia.

Case Description:

Three cases of PHPT in pregnancy are described. Each patient had severe hypercalcemia, described as a level greater than 11.4 mg/dL. Patients 1 and 2 were diagnosed in the third trimester, while Patient 3 was diagnosed in the first trimester. Patient 1 presented at 28 weeks gestation with a calcium of 11.9 mg/dL. Beginning at 30 weeks gestation, she was treated with daily intravenous fluids and calcitonin 4 international units (IU) per kilogram (kg) twice daily three days a week. At 37 weeks, her calcium was 11.7 mg/dL and she developed preeclampsia, requiring labor induction and delivery via C-section. Patient 2 presented with nephrolithiasis at 31 weeks gestation with a calcium of 12.6 mg/dL. Her course included many emergency department (ED) visits for hypercalcemia that minimally resolved with daily intravenous fluids and 1-2 doses of calcitonin 4 IU/kg given during the ED visits. At 37 weeks, her calcium remained 13-14 mg/dL despite treatment and she underwent induction of labor and delivery via C-section. Both babies had short stays in the NICU without complications. In patients 1 and 2, surgery was deferred until after delivery given diagnosis in the third trimester. Patient 3 presented at 5 weeks gestation with a calcium of 12.4 and was treated with oral hydration and Sensipar. At week 6, she presented to the ED with intractable nausea and vomiting, with a calcium of 14 and both the patient and fetus developed bradycardia. Parathyroidectomy was planned to be deferred until the second trimester; however, given the high risk of continued pregnancy, and the patient's wishes, the pregnancy was terminated at 7 weeks gestation. All three patients underwent parathyroidectomy postpartum with success. Post-partum, Patient 2 was diagnosed with severe bone loss and started on hormone replacement, with follow up bone density showing significant improvement.

Discussion:

Although the hypercalcemia seen in PHPT of pregnancy is usually mild, these cases demonstrate instances of uncontrolled hypercalcemia despite optimal medical management and variable clinical courses with complications. Thus, it is important to check calcium levels and address abnormalities prior to pregnancy to avoid complications.