Endocrine Abstracts

Hungry bone syndrome is common in tertiary hyperparathyroidism after parathyroidectomy. Less frequently, it has been described after thyroidectomy in patients with hyperthyroidism. We hereby report a case of hungry bone syndrome in a patient who suffers with Graves’ disease.

A 44-year-old woman with a history of refractory Graves’ disease presented with 4 weeks history of shortness of breath, palpitations and peri-oral paraesthesia following total thyroidectomy. She had previously been treated with high doses of carbimazole for 18 months followed by radioactive iodine. She remained thyrotoxic and after refusing further radioactive therapy underwent total thyroidectomy. Following post-operative hypocalcaemia she was discharged on Adcal 1.5 g TDS, Alfacalcidol 0.5 mg OD and levothyroxine 100 mcg. On the day of admission, laboratory results revealed a profound hypocalcaemia (total calcium 1.1 mmol/l; ionized calcium 0.53 mmol/l) and hyperphosphataemia (2.66 mmol/l) with undetectable levels of parathyroid hormone. Echocardiogram showed tachycardia with prolonged QT of 0.55 s. She was treated with intravenous calcium infusion which restored her calcium levels, however within 12 h her calcium levels fell rapidly, causing a tonic-clonic seizure. After initial stabilization with intravenous calcium administration, oral calcium carbonate and calcitriol were required. She continued to require intravenous calcium infusion every 2 to 3 days and her oral calcitriol supplementation was increased gradually to 16 mg daily over a period of four weeks. There was an unusually high need for calcium combined with a low calcium excretion in the urine. Bone-specific ALP continued to rise in the first few weeks indicating increased bone reconstruction. Following prolonged hospital stay, she was discharged on high doses of vitamin D and elemental calcium. Six months postoperatively it was possible to gradually reduce her calcitriol to 5 mg daily with 2 g calcium supplement. This case highlights hungry bone syndrome in a case of severe and prolonged thyrotoxicosis treated with total thyroidectomy. This condition can be monitored by the use of calcium profile investigations, including bone-specific ALP.