Endocrine Abstracts

Primary hyperparathyroidism (PHPT) affects approximately 0.3% of the UK population. The most frequent cause is solitary parathyroid adenoma, less commonly parathyroid hyperplasia, multiple adenomas, and parathyroid carcinoma. Cinacalcet is a calcimimetic which may be used in treatment of PHPT in certain circumstances. We report here a case of PHPT, treated by Cinacalcet, wherein apparently spontaneous necrosis of a parathyroid adenoma and resolution of hypercalcaemia occurred. A 58-year-old male with hypertension, alcohol misuse disorder and CKD (eGFR 50 ml/min/1.73m2) was referred for lethargy and abdominal pain. His usual medications included Enalapril, Lansoprazole and Atorvastatin. He was hypercalcaemic with an albumin adjusted serum calcium of 3.23 mmol/l (2.2 – 2.6) and Parathyroid Hormone (PTH) was 25.2 pmol/l (1.6 – 6.9). 25-OH-Vitamin D was 66 nmol/l (> 50), urine Calcium: Creatinine Clearance Ratio 0.0229. Overall this was consistent with PHPT. Parathyroid Single Photon Emission Computed Tomography (SPECT CT) scan showed a 3.8 cm lesion posterior to the lower pole of the right thyroid lobe with focal tracer uptake on its inferior margin suggestive of parathyroid adenoma. He was admitted, treated with IV fluids and discharged on Cinacalcet 30mg BD. Upon subsequent preoperative review, he was found to be hypocalcaemic, he reported a two-week history of change in voice. A palpable mass in the right neck anterior triangle was noted. Flexible nasendoscopy showed right vocal cord palsy. Cinacalcet therapy was suspended. Parathyroidectomy was performed and a 4 cm, partly necrotic lesion was removed from behind the right thyroid lobe. He was discharged on CALVIVE 1 g Effervescent Tablets. Histology confirmed an adenoma showing partial necrosis. We hypothesise that resolution of hypercalcaemia could have been due to Cinacalcet induced necrosis. We have identified two other similar case reports of remission of hypercalcaemia associated with parathyroid necrosis following Cinacalcet treatment in the literature.