Endocrine Abstracts

We report the case of a 41-year-old woman who was under investigation for deranged liver function tests following an insurance medical when she also serendipitously was found to have hypercalcaemia - 2.70 millimols per litre (Reference range 2.45-2.65 millimols per litre). She was completely asymptomatic and on no medication. She had an elevated Parathyroid hormone level of 11.6 picomols per litre (Reference range 0.9-8.0 picomols per litre), consistent with primary hyperparathyroidism. However the 24-hour urinary calcium levels were repeatedly low 2.2 millimols per collection and 1.7 millimols per collection (Reference range 2.5-7.5 millimols per collection). Her calculated calcium:creatinine clearance ratio was 0.0026. A value of less than 0.01 is suggestive of possible familial benign hypocalciuric hypercalcaemia. Screening of first-degree relatives did not demonstrate hypercalcaemia, although her mother was deceased and other key family members were unavailable. Parathyroid hormone can be raised in familial benign hypocalciuric hypercalcaemia and a low calcium:creatinine clearance is considered neither pathognomonic of familial benign hypocalciuric hypercalcaemia nor can it exclude primary hyperparathyroidism. The controversies in differentiating between the two conditions and the implications of conservative versus definitive treatment vary considerably, particularly in patients less than 50 years. Diagnosis in such situations can be difficult and further management challenging in view of the overlap in diagnostic criteria between mild primary hyperparathyroidism and familial benign hypocalciuric hypercalcaemia, which are both usually asymptomatic.