A 60 year old Caucasian woman was referred to endocrine clinic with persistent hypercalcaemia between 2.8 and 2.9 mmol/l (2.22.6), with inappropriately normal PTH at 7 pmol/l (1.487.63). Her hypercalcaemia was noted first in 2008. She had no signs or symptoms associated with hypercalcemia. However, she has a strong family history of hypercalcaemia, where her mother required Cinacalcet to control her hypercalcaemia despite two previous parathyroid resections. She has 3 children in their 30s who had not had calcium screening before. However, the son had a renal stone. There was no history of pancreatitis. Her creatinine was 105 mmol/l (eGFR 47). She received replacement for her 25OH vitamin D deficiency at 20.8 nmol/l. Under the context of strong family history of hypercalcaemia with normohormonal hyperparathyroidism, further tests were done to explore the possibility of FHH, or syndromic presentation such as Multiple Endocrine Neoplasia. Her anterior pituitary axes and plasma normetanephrine/metanephrine were normal. However, her urine calcium:creatinine clearance ratio was <0.01 with urine volume of 965ml/day leading to suspicion for FHH. A genetic screening revealed a heterogenous pathogenic variant in CASR: c.488C>G, p.(Pro163Arg), which is an extremely rare variant not listed in population frequency databases. This has previously been reported in patient with Tropical Chronic Pancreatitis (Murugaian, et al., 2008). Segregation studies in three families performed by the Oxford Genetics laboratory has shown the variant to segregate with hypercalcaemia in two affected first-degree relatives in each family. This is consistent with the clinical presentation in this patient. Therefore, we seek to offer her first-degree relatives genetic counselling and screening. This further emphasise the importance of investigating the calcium:creatinine clearance ratio and genetic testing for CASR mutations, (Familial hypocalciuric hypercalcaemia panel and isolated familial hyperparathyroidism panel) in the context of strong family history to avoid unwarranted parathyroid surgery.
19 Nov 2018 - 21 Nov 2018