SUN-819 - Giant Parathyroid Adenomas: A Case Series and Review of Literature

Background: Giant parathyroid adenomas (GPAs) represent a diverse set of tumors that range from benign adenomas to potentially malignant masses. Their mass is greater than 3-3.5 grams. GPAs account for 1-5% of all parathyroid masses and are associated with hypercalcemia, nephrolithiasis, renal disease, osteoporosis, or osteitis fibrosis cystica (OFC) in severe cases(1).

Objective: To characterize the clinical presentation, management, and outcomes of giant parathyroid adenomas (GPAs), defined as masses ≥3g, from a large single-institution series.

Methods: Retrospective analysis of 30 cases of GPA from October 2014 to September 2025. We reviewed demographics, presenting symptoms, complications, pre-operative biochemistry, localization studies, surgical approach, response to surgery, tumor pathology, and recurrence rates.

Results: Of the 30 cases, the majority were female (70%) with an average age of 61 at the time of surgery. The most common presenting symptoms included fatigue (36.7%), nephrolithiasis (26.7%), constipation (23.3%), and bone pain (16.7%). Pre-operative biochemical data revealed significant hypercalcemia (mean 12.6 mg/dL) and elevated PTH levels (mean 410 pg/mL). Pre-operative imaging included ultrasonography (53.3%), computed tomography (63.3%), and sestamibi scans (76.7%), and most tumors were effectively localized by one of these methods. Most surgeries completed were focused excisions (70%), achieving intraoperative PTH drop of >50% in 93 % of cases. GPA mass averaged 4.9 g (range 3.13-14.5g). Post-operative complications were infrequent (27%). The most common complications were transient hypocalcemia and hoarseness (13.3% each). Recurrent/persistent hyperparathyroidism occurred in 10 patients (33.3%), though no cases reported re-operation during the study period.

Conclusions: This single-institution series provides a comprehensive overview of GPAs, highlighting their variable clinical features. Compared to typical parathyroid tumors(2), GPAs are associated with more severe biochemical profiles at presentation and a higher rate of recurrent hyperparathyroidism, underscoring the need for vigilant follow-up.

References:
1. Aziz H, Hussein Z. Giant Parathyroid Adenoma versus Parathyroid Carcinoma: Differentiating Two Entities. J ASEAN Fed Endocr Soc. 2021;36(1):104-107.
2. Wilhelm SM, Wang TS, Ruan DT, et al. The American Association of Endocrine Surgeons Guidelines for Definitive Management of Primary Hyperparathyroidism. JAMA Surg. 2016;151(10):959-968.

*Unless otherwise noted, all abstracts presented at ENDO must not be released to the press or the public until the date and time of presentation. For oral presentations, the abstracts are embargoed until the session begins. The Endocrine Society reserves the right to lift the embargo on specific abstracts that are selected for promotion prior to or during ENDO.*