Endocrine Abstracts

A 33 year old man with Williams-Beuren Syndrome (WBS) was admitted following the finding of symptomatic hypercalcaemia (calcium 3.12 mmol/l (2.2-2.6)). Infantile hypercalcaemia is characteristic of WBS, however almost always, calcium levels return to the normal range by ~12 months of age. The patient also had an acute kidney injury (eGFR 39ml/min/1.73², creatinine 178 mmol/l (59-104)), secondary to hypercalcaemia. The patient complained of polydipsia. Past medical history included features typical of WBS such as supra-valvular aortic stenosis, pulmonary stenosis hypertension, intellectual disability and previous endocarditis. Medications included warfarin and bisoprolol. The hypercalcaemia was initially considered to be secondary to excessive calcium ingestion, as the patient drank 4-6 pints of milk per day. However, following a reduction in intake to 1 pint per day, calcium levels measured 2.98 mmol/l, prompting further investigations. Hyperparathyroidism and excess vitamin D were ruled out as potential causes with PTH 2.2 pmol/l (1.9-6.4) and 25OH Vitamin D 31 nmol/l (>50). There were no clinical or radiological features suggestive of a malignant or granulomatous cause. A trial of cinacalcet (30 mg BD) failed to resolve the hypercalcaemia (calcium 3.06 mmol/l), therefore this was discontinued. The patient was commenced on IV pamidronate (60 mg). Six weeks following the infusion, the hypercalcaemia had returned to the reference range (calcium 2.54 mmol/l). On-going monitoring delineated further hypercalcaemia ten months post-infusion (calcium 2.84 mmol/l). Therefore, the patient required another pamidronate infusion, which once again lowered calcium levels. The frequency of pamidronate infusions since has been on a 6-12 monthly basis. Renal function has recovered following the correction of his hypercalcaemia (eGFR 68 and creatinine 109). The continuing management plan for this patient includes long term calcium and vitamin D monitoring and pamidronate infusions as required. In patients with WBS, consideration should be given to 6-12 monthly calcium assessment, even in adulthood and consideration of treatment on a similar frequency with bisphosphonates.