Endocrine Abstracts

Agranuloctosis is a rare and serious complication of Carbimazole. (risk <1/10⁶ of population/year. It is associated with higher doses. We report two cases over 1 year in patients exposed to amiodarone.

Case 1: A 63 year old man with ischemic cardiomyopathy had been treated with amiodarone for atrial fibrillation for 3 years. 6 months after stopping he developed symptomatic thyrotoxicosis and started on carbimazole 60 mg per day. Thyroid T^c uptake was low. (Probable type 1 or mixed amiodarone thyrotoxicosis AIT). 3 months later he presented with sepsis and a neutrophil count of 0.010×10⁹/l and was treated with Filgrastim and antibiotics. Granulocytes rose >1.000×10⁹/l on day nine of treatment Thyrotoxicosis resolved after 3 months on prednisolone and a short course of potassium perchlorate.

Case 2: A 72 year old female with atrial fibrillation, diabetes and ES renal disease previously on amiodarone for 2 years developed symptomatic thyrotoxicosis and treated with carbimazole 60 mg per day on a reducing regime. 2 months later she developed agranulocytosis and sepsis: neutrophil count: 0.010×10⁹/l. Probable type 2 AIT induced thyrotoxicosis. She was treated with Filgrastim and antibiotics.Neutrophil count rose over 1.000×10⁹ after 6 days. She became euthyroid after prednisone therapy.

Risk for carbimazole induced agranulocytosis may be do the combination of high doses and older age predisposing these patients to agranulocytosis. Because of the cross reactivity of antithyroid drugs treatment of thyrotoxicosis is particularly difficult with the risk of thyroid storm during sepsis. Amiodarone induced thyrotoxicosis can be slow to respond to antithyroid drugs and higher doses are often necessary. Both our patients had accelerated recovery with Filgrastim. We advise caution with high antithyroid drug doses in amiodarone induced thyrotoxicosis and suggest considering combined therapy early.