Exceedingly Hyper-Secreting Parathyroid Adenoma: A Literature Review and Case Series

Background: Hypercalcemia is most commonly caused by hyperparathyroidism, which is often due to the presence of a parathyroid adenoma and more rarely, a parathyroid carcinoma. Distinguishing between the two can be challenging when serum calcium and parathyroid hormone (PTH) levels are severely elevated. Carcinomas classically present with markedly increased values and more severe clinical symptoms. Methods: Clinical data was obtained via retrospective chart review and literature review. Results: Three cases of female patients with symptomatic hypercalcemia from primary hyperparathyroidism with markedly elevated PTH levels (755–3547.4 pg/mL) underwent uncomplicated parathyroid adenoma excision with no histopathologic evidence of malignancy. Appropriate intraoperative reduction in PTH levels was observed, and all patients experienced normalization in calcium levels postoperatively. There is a notable deficit in available literature regarding similar cases. Conclusions: Given the rarity of parathyroid carcinoma, these exceptional cases and laboratory values serve as a valuable reminder for clinicians about the diverse presentations of adenomas.