Hypercalcemia in pregnancy can result from either PTH-dependent mechanisms, including primary hyperparathyroidism and familial hypocalciuric hypercalcemia, or PTH-independent mechanisms, including PTHrP-mediated hypercalcemia of pregnancy, milk-alkali syndrome, abnormal vitamin D metabolism, malignancy, and drugs.1 Here we present a case of a rare cause of hypercalcemia in pregnancy, highlighting the challenges in diagnosis and management of this disease. The gene discussed is PTH; the disease is primary hyperparathyroidism.