Endocrine Abstracts

Case Presentation: A 27-year-old female who recently moved to the UK, was referred to Endocrinology with suspected thyrotoxicosis. She was diagnosed with thyrotoxicosis 11 years prior, and was temporarily treated with a ‘block and replace’ regimen. She had history of traumatic brain injury with no long-term sequelae, and cholecystectomy leading to chronic diarrhoea. She reported swallowing difficulty and a choking sensation. Investigations identified hyperthyroidism due to multi-nodular goitre. Thyroid receptor antibodies were initially negative, but weakly positive on follow up (0.9I U/l), indicating Graves’ disease. A thyroid ultrasound revealed three U3 thyroid nodules with maximal diameter of 32 mm. These were benign (THY2) on fine needle aspiration. She remained thyrotoxic despite titration of carbimazole to 20 mg daily, over 3 years. A follow-up ultrasound showed interval increase in nodule size, with maximal diameter of 36 mm and U3 classification. The patient’s TSH remained suppressed (<0.01 mU/l) and she remained symptomatic. The decision was made to proceed to thyroidectomy. Simultaneously, she was noted to have asymptomatic severe hypocalcaemia (adjusted calcium 1.46 mmol/l, vitamin D 54.6 nmol/l, PTH 1.4 pmol/l, magnesium 0.63 mmol/l, phosphate 2.50 mmol/l). She reported repeated childhood hospital admissions requiring intravenous calcium infusions, but was unsure of the cause. Parathyroid antibodies were negative. She was diagnosed with hypocalcaemic hypoparathyroidism and was commenced on Adcal-D3, Alfacalcidol and Magnesium supplementation. She suffered repeated hospital admissions, despite titration of Alfacalcidol to 2.5 mg daily, Adcal D3 to 4 tablets daily and Magnesium 10 mmol sachets twice daily. She was initially asymptomatic, however more recent hospital admissions were complicated by seizures alongside hypocalcaemia. She was commenced on levetiracetam and referred for neurological assessment. As her calcium failed to normalise, underlying bile acid malabsorption was suspected, due to ongoing diarrhoea. She was commenced on Colesevelam 1250 mg daily after gastroenterology input. On latest follow-up, her adjusted calcium is stable at 2.12 mmol/l, with magnesium of 0.64 mmol/l. She still awaits thyroidectomy.

Discussion: This is a complex case of refractory hypocalcaemia in a patient with significant co-morbidities. Her previous traumatic brain injury has likely lowered the seizure threshold, with hypocalcaemia possibly exacerbating seizure episodes. Exploring and treating other reasons for persistent hypocalcaemia, including malabsorption, was paramount in this case. Careful consideration and planning will be required prior to thyroidectomy, to avoid post-operative hypocalcaemia. The risk is significant due to her concurrent Graves’ disease and hypoparathyroidism. A pre-load regime of higher dose Alfacalcidol has been planned prior to her thyroidectomy.