Endocrine Abstracts

JOINT3978

Background: Parathyroid adenoma and hyperplasia are common causes of hyperparathyroidism, with solitary adenomas accounting for 85% to 90% of cases, while multiple gland hyperplasia constitutes approximately 10% to 15%. These typically result in moderately elevated PTH levels compared to carcinomas, which can reach significantly higher levels. Here, we present a case of aggressive parathyroid hyperplasia with severely elevated PTH.

Case Summary: An 86-year-old woman presented to the Emergency Department with drowsiness, weakness in her legs, polyuria, and abdominal pain. She had a history of longstanding constipation and unintentional weight loss, which the surgical team had already investigated; a CT scan of the thorax, abdomen, and pelvis ruled out malignancy. Initial investigations revealed severe hypercalcaemia (serum adjusted calcium 4.48 mmol/l, reference range 2.17 – 2.56 mmol/l) and hypokalaemia (serum potassium 2.4 mmol/l, reference range 3.5 – 5.3 mmol/l). The ECG was unremarkable. Work-up for hypercalcaemia indicated raised PTH-191.7 pmol/l (2.0-8.5), with normal inorganic phosphate at 1.02 mmol/l (0.8 – 1.5). Daily serum-adjusted calcium monitoring demonstrated a rising trend, reaching up to 5.11 mmol/l. She was treated with IV fluids, dexamethasone, zoledronic acid, and calcitonin. A CT scan and ultrasound of the neck revealed a 2.8 cm mass at the posterolateral aspect of the left thyroid nodule, with no lymphadenopathy, raising suspicion for parathyroid carcinoma as the primary differential. She was referred to the Parathyroid MDT and underwent an urgent parathyroidectomy. Surgery revealed left-sided superior and right inferior parathyroid lesions. Intraoperative PTH was 49.5 pmol/l and exploration for ectopic parathyroid tissue was undertaken, but none was found; immediate postoperative PTH was 25.3 pmol/l. Histopathology confirmed two glands of parathyroid hyperplasia with no evidence of malignancy. She was alert to time, place, and person post-surgery, achieving a GCS of 15/15. Her serum-adjusted calcium and PTH levels gradually normalised, leading to her discharge.

Conclusion: Such high PTH levels in parathyroid adenomas (PA) are rare and typically associated with parathyroid carcinoma. This case encourages consideration of suspected parathyroid carcinoma; however, it was ultimately determined to be (2-gland) parathyroid hyperplasia (PH). Genetic mutations, particularly MEN1 and cyclin D1, are noted in PH and PA; however, our patient did not have a known family history, so further genetic testing has been deferred.