MON-LB64 Primary Hyperparathyroidism With Severe Hypercalcemia During Pregnancy: A Challenging Diagnosis and Management

Background:Primary Hyperparathyroidism (PHPT) is rare in pregnancy and the physiological adaptations in mineral and skeletal homeostasis that occur during gestation need to be taken into consideration for the diagnosis and management. Clinical case:A 30-year-old primgravid woman with history of kidney stones presented at our institution during the 13(th) week of twin gestation with severe nausea and vomiting. She had previously been hospitalized at 9 weeks for hypercalcemia and acute kidney injury, and treated with steroids for presumed granulomatous disease without improvement. She was on prenatal vitamins and family history was significant for kidney stones, but not hypercalcemia. At admission, calcium was 14.4 mg/dl, ionized calcium 1.89 mmol/L (1.16-1.32), PTH 15.2 pg/ml (12-88), albumin 3.4 g/dl, phosphorus 2.1 mg/dl, and creatinine 1.8 mg/dl. PTHrP was <2 pmol/L (<4.2) and 1, 25-dihydroxyvitamin D was 191 pg/mL (2(nd) trimester range 72-160 pg/ml). She was treated with IV hydration, but her calcium remained elevated and severe hypercalcemia recurred after stopping hydration. She underwent neck exploration and right upper parathyroidectomy in the second trimester. The other parathyroid glands were noted to be normal. Intraoperative PTH dropped from 25.2 pg/mL to 4.4 pg/mL. Final pathology showed a hypercellular parathyroid. Her calcium dropped to normal levels in the early postoperative period. Calcitonin was initiated by another provider two weeks postoperatively for persistent mild hypercalcemia. Her calcium levels remained at the upper limit of normal during her 2(nd) and 3(rd) trimesters. PTH remained suppressed at 3.2 pg/ml. She had a C-section at 34 weeks for premature rupture of membranes. Her twins did not develop hypocalcemia or hypoparathyroidism. The most recent postpartum calcium was 9.2 mg/dl with PTH 3.3 pg/ml.Conclusions:Our case highlights the challenge in the diagnosis and management of PHPT in pregnancy. During pregnancy, PHPT is diagnosed by elevated ionized or albumin corrected calcium and non-suppressed PTH level. It is important to note that 1,25-dihydroxyvitamin D levels physiologically increase in the second and third trimester. Since both PHPT and pregnancy cause intestinal calcium absorption and bone resorption, PHPT during pregnancy has increased risk of severe hypercalcemia, pancreatitis and renal stones. During the third trimester the transfer of calcium through the placenta and the uptake of calcium by the fetal skeleton can protect against severe hypercalcemia. However, hypercalcemic crisis can occur because of the peak release of PTHrP by the placenta and breasts, or after delivery due to loss of calcium transfer to the placenta. Parathyroidectomy is preferably performed in the second trimester to reduce fetal and maternal complications. After delivery neonatal hypocalcemia can have a delayed onset, a prolonged course and could be permanent.