Endocrine Abstracts

Background: Hypercalcaemia is a well-recognised feature amongst children with Williams-Beuren syndrome with a reported incidence between 0-43%¹. In most cases this is mild however in some, reportedly 6.1% (Sindhar et al.¹) it is severe enough for it to be actionable and cause nephrocalcinosis. We present 2 cases of severe hypercalcaemia requiring treatment with bisphosphonates.

Case 1: A 16 month old male admitted following routine bloods due to developmental delay and recently having been more unsettled. Bloods revealed acute kidney injury (AKI) with urea 15.2 mmol/l and creatinine 73 umol/l with hypercalcemia of 3.26 mmol/l. He was commenced on 200% hyper-hydration with furosemide cover. His calcium level remained high at 3.14 mmol/l therefore his IVF were stopped and he was managed with a pamidronate infusion. The dose was discussed with the renal team given his AKI and hypertension (132/88). He responded well as his calcium fell to 2.6 mmol/l. He required a further pamidronate infusion 2 weeks later as his calcium level had risen to 3 mmol/l. Both infusions were well tolerated.

Case 2 : 17 month old male with known Williams-Beuren syndrome admitted with vomiting, cough & lethargy. Bloods showed calcium of 3.5 mmol/l. Parents felt he had low tone, poor appetite and constipation. Due to difficult IV access he was managed initially with increased oral fluids which improved calcium to 2.67 mmol/l however his calcium increased further to 4.4 mmol/l. He received hyper-hydration and furosemide. After 48 hrs of hyper-hydration his adjusted calcium remained high (3.04 mmol/l) therefore he received one dose of IV pamidronate. He had no side effects or acute phase reaction and calcium normalised to 2.46. Both cases were managed with a low calcium diet and USS showed evidence of medullary nephrocalcinosis.

Conclusion: Severe and refractory hypercalcaemia is uncommon but potential harmful condition seen in Williams-Beuren syndrome. Early recognition of the condition and appropriate treatment are essential to optimise outcomes in such patient group. We have also shown that pamidronate has been well tolerated in the presence of AKI.