Endocrine Abstracts

Background: Primary hyperparathyroidism is a relatively common endocrine disorder. Familial hypocalciuric hypercalcaemia is an important differential diagnosis but is much less prevalent. We examine a case of hypercalcaemia where there was some initial diagnostic uncertainty.

Case report: a 55-year-old lady was referred from primary care with mild hypercalcaemia, low mood, constipation and urinary frequency. She had a previous history of renal stones at the age of 38, a previous clavicular fracture and no history of renal disease. Her mother has a history of osteoporosis but there is no other family history of calcium-related disorders. She was not on any diuretics or any calcium supplements. Initial blood tests from primary care showed an adjusted calcium of 2.64 with a PTH of 14 and a Vitamin D level of 60.5. An initial calcium creatinine clearance ratio in secondary care came back at 0.0049, a result more consistent with familial hypocalciuric hypercalcaemia than primary hyperparathyroidism. A renal tract ultrasound as well as a DEXA scan showed no abnormalities. A repeat calcium creatinine clearance ratio came back as inconclusive (< 0.014), with a repeat adjusted calcium of 2.69, a PTH of 11.9 and a Vitamin D level of 51. The clinical suspicion of primary hyperparathyroidism remained, so an ultrasound of the parathyroid gland and a SestaMIBI SPECT scan were requested. These both showed evidence of a left-sided inferior parathyroid adenoma. A third calcium creatinine clearance ratio was positive at 0.021 and primary hyperparathyroidism was finally diagnosed.