Abstract #1402502: Hypercalcemia of Malignancy in Pregnancy, a Management Dilemma

Abstract

Hypercalcemia of Malignancy (HCM) is a complication that is typically managed with bisphosphonates (BP). However, BP are not studied in pregnant patients with HCM and avoided due to potential adverse outcomes on mother and fetus thus limiting available options to manage hypercalcemia in pregnancy. We describe a case of HCM in a pregnant patient managed with Zoledronic acid. 36-year-old female, 32 weeks pregnant diagnosed during pregnancy with stage IV Breast cancer with liver and bone metastases, was admitted with hypercalcemia with no previous history. She did not have renal stones, polyuria, constipation, bone pain, fractures or taking calcium supplements. Lab data showed high calcium 12.9mg/dl, low PTH 5pg/ml, 25-OH vitamin D 15.5ng/ml, 1,25 OH vitamin D 70.28pg/ml, high PTHrP 6.1pmol/L. She received IV fluids and calcitonin with minimal benefit. After weighing risks and benefit and discussion with other teams, she was given IV Zoledronic acid. With chemotherapy and hypercalcemia, she developed severe emesis and decreased oral intake resulting in dehydration, low magnesium and phosphorus. She developed arrhythmia, frequent uterine contractions and fetal tachycardia and was treated for preterm labor with steroids, penicillin prophylaxis, aggressive hydration, and electrolyte replacement. Preterm delivery was safely avoided. After 4 days of BP dose, calcium normalized to 8.2 mg/dL and she was stable to be discharged home. She later received second cycle of chemotherapy and had uncomplicated vaginal delivery at 38 weeks with no neonatal complications. There are few studies on use of BP in pregnancy showing no increased risk of serious adverse effects. A systematic review of 51 cases with exposure to BP before or during pregnancy did not result in skeletal abnormalities or congenital malformations in the infants. In another case control study of 36 women with BP exposure, no major teratogenic effects were found but rates of neonatal complications were increased in women with systemic diseases, as were spontaneous abortions for women with bone disease. One case of 24 weeks pregnant female with metastatic breast cancer, pamidronate improved HCM and uterine contractions with no adverse effects on neonate. In our patient, treating hypercalcemia was necessary to avoid severe complications. We treated her with zoledronic acid as it is more effective then pamidronate at normalizing calcium and has similar safety profile. We optimized hydration status and monitored electrolytes to mitigate risk of side effects expected from BP use with good maternal and fetal results. More studies are required to determine safe use of BP in pregnant patients to guide management and avoid complications of HCM in mother and fetus.