Endocrine Abstracts

Introduction: It is rare for someone with FHH to have co-existing primary hyperparathyroidism. We describe a case of a 50-year-old woman who was assumed to have FHH due to her strong family history of hypercalcaemia. However, her recurrent admissions with hypercalcaemia prompted further investigations that suggested primary hyperparathyroidism.

Clinical History: Patient was known to have hypercalcaemia since age of 12 years. Father had parathyroidectomy, her sister, children and grandchildren were also known to have hypercalcaemia. However, none had any diagnostic genetic testing. Since 2019 she attended emergency department 5 times due to symptoms of palpitations, nausea and headache. Three of these visits occurred in the past 12 months.

Diagnostics: Initial tests in primary care in 2018 showed PTH 7.8 pmol/L, adjusted calcium 3.15mmol and phosphate of 0.59mmol/L. In 2019 her PTH was 11.8pmol/L and recently it was 16.9pmol/L. Her adjusted calcium remained above 3.10 mmol since 2018. 24hr Urine Calcium was 2.19mmol/24hr (low) in 2019 and 4.00 mmol/24hr (normal) in 2022. Her DXA and renal ultrasound were normal. MIBI/SPECT CT in 2020 revealed no abnormality. However, Ultrasound of Neck in 2023 showed 8mm nodule close to trachea and a repeat MIBI/SPECT CT revealed a 7mm nodule in the tracheo-oesophageal groove. Genetic testing in 2024 was positive for heterozygous variant in CASR causing FHH Type 1.

Management: Her symptoms during admissions were managed with intravenous fluids and bisphosphonates. In late 2023 she was prescribed Cinacalcet 30mg twice daily which was later increased to 90mg three times daily. Currently she is awaiting surgery

Conclusion: This case elucidates that progressive rise in PTH and recurrent admissions with symptomatic hypercalcaemia despite high doses of cinacalcet were important cues for an additional cause of hypercalcaemia.