Postoperative Hypocalcemia Following Parathyroidectomy for Giant Parathyroid Adenoma

ABSTRACT Objective Giant parathyroid adenomas (GPAs) are a rare type of parathyroid adenoma (PA) weighing >2 to 3 g. The objective of this manuscript is to report a case of giant parathyroid adenoma and highlight the risk of postoperative hypocalcemia. Methods We describe the presentation and work-up of a woman with GPA confirmed with histopathology as well as management of postoperative hypocalcemia. Results A 66-year-old Caucasian female with chronic fatigue was found to have elevated calcium levels at 13.7 mg/dL (normal, 8.9 to 10.2 mg/dL) and elevated parathyroid hormone levels at 1,240 pg/mL (normal, 12 to 72 pg/mL). Contrast enhanced computed tomography scan of the neck showed a 5.6 cm heterogeneous mass posterior to the right thyroid. The patient underwent right parathyroidectomy and histopathology confirmed the diagnosis of a giant parathyroid adenoma (GPA) weighing 28.7 g. Postoperatively, the patient developed hypocalcemia secondary to hungry bone syndrome and was treated aggressively with intravenous calcium supplementation. At 4 weeks postoperatively, she had normal calcium levels without any calcium supplementation. Conclusion GPAs are a rare variant of PA, and could be a distinct clinical entity with features different from both PA and parathyroid carcinoma. We further postulate that the risk of postoperative hypocalcemia secondary to hungry bone syndrome could be higher among patients with GPA compared to patients with PA. These hypotheses needs to be validated with further studies. Abbreviations CT computed tomography GPA giant parathyroid adenoma HBS hungry bone syndrome PA parathyroid adenoma PTH parathyroid hormone