SAT-400 Management Of Type II Amiodarone-induced Thyrotoxicosis With Low Dose Prednisone And Colestipol, A Bile Acid Binding Resin

Abstract Disclosure: A.J. Spiro: None. N.O. Vietor: None. T.D. Hoang: None. M.K. Shakir: None. The risk of amiodarone-induced thyrotoxicosis (AIT) increases with higher cumulative doses of amiodarone. For most patients with type 2 AIT, initial treatment with glucocorticoids (oral prednisone, 30 to 40 mg/day) rather than other therapies is suggested. However, in patients with type 2 AIT and active hepatitis B infection, treatment with high-dose prednisone is relatively contraindicated. We report a patient with type 2 AIT, treated with a combination of relatively low dose prednisone and colestipol, a bile acid binding resin.A 68-year-old man presented for evaluation of recent onset thyrotoxicosis. He was seen by cardiology for non-ischemic cardiomyopathy, systolic heart failure, and atrial fibrillation. Baseline thyroid function tests were normal. He was treated with amiodarone 6 months ago, but with onset of thyrotoxicosis, he was switched to dronedarone. He also had active hepatitis B. He was physically active with no exertional symptoms. His vital signs were normal and had no evidence of thyroid eye disease. Thyroid examination was normal with a 20-gram gland without nodules or tenderness. Lab tests showed TSH 0.001 uIU/mL(0.450 − 4.500) , free T4 2.02 ng/dL(0.82 − 1.77) , total T3 211 ng/dL(71 − 180), TSI <0.1 IU/L(0.00 - 0.55), reverse T3 37.5 ng/dL(9.2 - 24.1), serum iodine 559 ug/L(40.0 - 92.0), HBV 34,880 IU/mL(>20,000 significant), ALT 82 IU/L(0 − 44), AST 74 IU/L(0 − 40). Thyroid ultrasound with Doppler color showed absent vascular flow (pattern 0). A Tc-99m pertechnetate scintigraphy showed low uptake. Chronic HBV infection was also diagnosed and antiviral treatment with tenofovir was considered, although the treatment could not be initiated because of the need for steroid treatment. He was started on a low dose 25 mg prednisone and colestipol 3 gms daily. Two months later laboratory studies showed TSH 0.03 uIU/mL(0.450 − 4.500), free T4 1.99 ng/dL(0.82 − 1.77) , serum iodine 582 ug/L40.0 - 92.0). Five months later, prednisone was tapered to 7.5 mg daily and labs showed TSH 0.99 uIU/L(0.450 − 4.500), free T4 1.56 ng/dL(0.82 − 1.77) and total T3 130 ng/dL(71 − 180). The liver associated enzymes remained stable. At present, it is planned to taper prednisone and initiate the antiviral treatment.Conclusion: Colestipol, a bile acid binding resin has dual mechanism of action in the management of thyrotoxicosis associated with thyroiditis. Bile-salt sequestrants bind thyroid hormones in the intestine and thereby increase their fecal excretion. Studies have also indicated that colestipol significantly reduces the enterohepatic circulation of amiodarone and lowers the serum levels of amiodarone. Therefore, combination therapy with bile acid binding resins along with low dose prednisone can be utilized in patients with type II AIT. Presentation: Saturday, July 12, 2025