Do giant parathyroid adenomas represent a distinct clinical entity?

Background. The size of abnormal parathyroid glands in patients with primary hyperparathyroidism (PHPT) is highly variable, but the clinical significance of giant glands is unknown. Methods. We reviewed 300 consecutive patients after parathyroidectomy for PHPT. We compared patients with giant parathyroid adenomas (weight >= 95th percentile) with the remaining patients. Results. Giant adenomas were defined as weight >= 95th percentile or 3.5 g (median, 0.61; range, 0.05-29.93). Patients with giant adenomas had a greater mean preoperative calcium level, greater mean parathyroid hormone (PTH) level, and were less likely to have multiglandular or symptomatic disease. Giant adenomas were successfully localized on imaging in 87% of patients, which was not increased over other patients (82%). There were no differences between the groups in age, gender, gland location, or the incidence of persistent or recurrent hyperparathyroidism. Finally, giant glands had an increased incidence of symptomatic postoperative hypocalcemia, including 1 patient who required rehospitalization after removal of a giant gland. Conclusion. Giant parathyroid adenomas have a distinct presentation characterized by single gland disease and lower incidence of symptoms despite increased levels of calcium and PTH. Additionally, after resection of a giant adenoma, patients are more likely to develop symptomatic hypocalcemia.