Endocrine Abstracts

Introduction: Primary hyperparathyroidism may be sporadic or occur as part of a genetic predisposition. Inactivation of CDC73 tumour suppressor gene can cause hyperparathyroidism-jaw tumour (HPT-IJ) syndrome, parathyroid carcinoma or familial isolated hyperparathyroidism (FIHP).

Case details: We report a 26 year old gentleman, previously fit and well who was found to have hypercalcemia on a routine testing. Renal ultrasound demonstrated nephrocalcinosis. He was referred to hospital with adjusted calcium 3.60 mmol/l (2.20-2.60), PTH 31.3 pmol/l (1.6-6.9), phosphate 0.64 mmol/l (0.80-1.50) which were keeping with primary hyperparathyroidism. He was given IV bisphosphonate by the acute team for persistent hypercalcemia. He described non-specific symptoms of lethargy but had no jaw pain or clinical history to suggest a syndromic cause. His maternal grandfather had kidney stones and mother had a hysterectomy. Genetic tests were sent but pending results, samples were sent for calcitonin and plasma metanephrines as these may alter the treatment course. Both results were normal. The USS parathyroid scan and 99m Tc-MIBI scan demonstrated a parathyroid adenoma inferior to the left thyroid lobe. He started cinacalcet pending operative treatment. Genetic testing identified a pathogenic variant in CDC73. Family have been advised about cascade screening.

Discussion: This case highlights the importance of genetic testing in young patients with hyperparathyroidism. It also demonstrates a pathway for necessary pre-operative testing in those needing more urgent parathyroid surgery, where genetic results may be delayed. Concurrent phaeochromocytoma or medullary thyroid carcinoma as part of MEN2 could alter operative treatment approach. Increased identification may allow for more detailed screening recommendations in family members with CDC73 mutations. Current recommendations suggest annual parathyroid biochemistry alongside dental check-up and periodic pelvic ultrasound to evaluate for uterine tumours in women of reproductive age.