Endocrine Abstracts

The commonest cause of hypercalcaemia is primary hyperparathyroidism (PHPTH). The diagnostic work up includes paired blood samples for serum corrected calcium, parathyroid hormone (PTH) and vitamin D levels. But in young patients, rare genetic conditions could be contributing towards hypercalcaemia and hence could produce a diagnostic challenge. We report hypercalcaemia work up in two young females where genetic tests were required.

Case 1

A 19yr girl presented with fatigue and osmotic symptoms. She is noted to have mild hypercalcaemia (2.61–2.77 mmol/l) since the age of 13 yrs. Her PTH was persistently high (7.8–14.4 pmol/l) with normal vitamin D (71–83 nmol/l) supporting a diagnosis of primary hyperparathyroidism. Her urinary calcium excretion suggested possibility of familial hypocalciuric hypercalcaemia (FHH). Her parathyroid imaging showed bilateral parathyroid adenomas and she was also noted to have raised prolactin along with a pituitary incidentaloma. Her case was discussed in MDT. Since she was a teenager with PHPTH with multiple gland involvement, it was decided to exclude multiple endocrine neoplasia (MEN). Due to her low urinary calcium excretion, it was also advised to exclude FHH. Genetic tests were sent for both conditions and were reported as normal. Her parathyroid imaging (4D CT scan, SESTAMIBI and Ultrasound) was reviewed in MDT again it was decided to proceed with right superior parathyroidectomy. This resolved hypercalcemia (corrected calcium = 2.39 mmol/l, PTH = 2.8 pmol/l). Histology confirmed parathyroid adenoma.

Case 2

A 42 yr lady presented with incidental hypercalcaemia (2.7–3.05 mmol/l) with normal PTH on routine blood tests. She had mild symptoms of constipation, fatigue, lower back pain. There was no osteoporosis or nephrocalcinosis on DEXA and US scans, respectively. Parathyroid imaging (4D CT scan, SESTAMIBI and Ultrasound) failed to identify any adenoma. Her urinary calcium excretion was low which suggested possibility of familial hypocalciuric hypercalcaemia (FHH). The genetic tests for FHH were organised which confirmed heterozygous mutation for CASR supporting the diagnosis of FHH type 1. The patient was reassured with no further treatment of her hypercalcaemia however, genetic work up was offered for her family to avoid unnecessary work up in incidental hypercalcaemia. Both these cases highlight important message of genetic workup in cases of hypercalcaemia with suspected hyperparathyroidism. In teenage patients with multi-gland disease and those with imaging negative primary hyperparathyroidism one should consider doing genetic tests for MEN and FHH. This avoids unnecessary interventions and also prevents missing serious conditions associated with MEN.