Endocrine Abstracts

Two weeks after fracturing his humerus a 14-year-old male presented with ongoing epigastric pain and vomiting. He was persistently tachycardic but normotensive. Treatment with intravenous fluids and ranitidine, for a presumed gastritis, was commenced.

Initial blood tests revealed a mildly raised urea and creatinine, normal inflammatory markers and full blood count. Further investigation showed a moderate hypercalcaemia with an albumin adjusted calcium of 3.05 mmol/l.

Despite comments on being thin it was a more detailed examination that exposed his exophthalmus, lid lag and goitre.

Thyroid function tests results gave a TSH of <0.05 mIU/l (0.3–5.5 mIU/l), free T4 of >100 pmol/l (12–22 pmol/l) and a free T3 of 28.7 pmol/l (3.1–6.8 pmol/l).

Hypercalcaemia is an uncommon consequence of thyrotoxicosis. Thyrotoxicoxis can cause sufficient bone resorption to increase serum calcium, decrease serum parathyroid hormone and increase urinary excretion of calcium. Hypercalcaemia should resolve when the patient is euthyroid.

Treating this patient presented some challenges. This case will demonstrate the mechanisms for and management of hypercalcaemia in thyrotoxicosis.