Endocrine Abstracts

Section 1: Case history: At the age of 18 our patient presented with renal stones and was diagnosed with Primary Hyperparathyroidism (PHPT). At 20 she underwent a right sided nephrectomy for a calculus associated non-functioning kidney. Over the years she has had numerous renal calculi, ureteric obstructions with stents, requiring urology input. Of note she had osteoporosis, hypertension, pancreatitis, gastritis, intracranial hypertension (with shunt in situ) and resistant Vitamin D deficiency. She was partially blind. Her late mother and brother also had renal stones, but no cause was identified. Her offspring remain normocalcaemic and asymptomatic. Referred for parathyroidectomy where she was diagnosed with familial hypocalciuric hypercalcaemia (FHH), a genetic disorder of phosphocalcic metabolism which is usually asymptomatic.

Section 2: Investigations: Between 2001 to 2019 her adjusted calcium varied between 2.4–2.8 mmol/l. Vitamin D persistently remained low. PTH ranged from 32–298 mmol/l. 24–hour urinary Calcium/creatinine ratio: 0.23. No paired bloods were done. Ultrasound parathyroid showed possible ectopic parathyroid lateral to the right lobe of the thyroid gland. Parathyroid SPECT CT showed generally homogenous uptake in thyroid except in the region of the right lower pole. DEXA SCAN showed: Spine T score –3.6, Hip T score –3.6 and Neck of femur T score –3.5.

Section 3: Results and treatment: Cinacalet 30 mg once a day was started but calcium levels remained unchanged. Cholecalciferol 50,000 IU was also started but Vitamin D remained persistently low. Bisphosphonate therapy was withheld due to dental complications. Despite compliance, remained symptomatic. Prior to four gland exploration, genetic testing was requested in 2020. A mosaicism mutation in CASR gene was identified.

Section 4: Conclusions and points for discussion: FHH is generally considered a benign disorder. Our patient was diagnosed with FHH 38 years after her diagnosis of primary hyperparathyroidism. Unusually, she developed multiple complications associated with (PHPT). This case highlights that FHH may not be benign. Points for discussion. 1. Urinary calcium should be evaluated in all cases of PHPT. 2. FHH may not be a benign disease as usually stated. 3. Management of symptomatic FHH is complex and needs MDT input. 4. How should this patient be managed further?