Cholestyramine as monotherapy for thyrotoxicosis: experience at a tertiary care centre during COVID-19 pandemic

Fizzah Iqbal; Win Yin; Lakshmi Nijith; Andrew Lansdown; Peter Taylor; Justyna Witczak

doi:10.1530/endoabs.86.CC7

Introduction: Thionamides are the mainstay of management of thyrotoxicosis but can be associated with adverse effects like agranulocystosis, hepatitis and vasculitis. While radioactive iodine and thyroidectomy can be utilized in such scenarios, they were not timely available during the COVID pandemic. We present our experience of using cholestyramine as monotherapy.

Case Series: Our series consists of four females. Graves’ disease was the underlying aetiology in all cases (three TSI antibody positive and one TSI antibody negative). The cholestyramine dose used varied between 2-4g bd and all patients achieved clinical and biochemical euthyroidism. Age at diagnosis, adverse effects with thionamides and treatment trajectory following cholestyramine therapy are summarized below:


Case 1 (19years)	Nausea and vomiting with both carbimazole and propylthiouracil (patient lactose intolerant). Completed 10 months of treatment with cholestyramine and remains in remission
Case 2 (61 years)	Mild persistent neutropenia-resolved after carbimazole cessation. Underwent RAI 2 years after initial diagnosis and euthyroid currently.
Case 3 (74 years)	Rash with carbimazole, ALT elevation with propylthiouracil. RAI 6 months after initial diagnosis with post-therapy hypothyroidism.
Case 4 (19 years)	Mouth ulcers with carbimazole; rash and arthralgias with propylthiouracil. Cholestyramine discontinued 4 months after treatment due to discolouration of teeth. Restarted on low dose propylthiouracil and tolerating well.

Conclusion: Thyroid hormones undergo hepatic clearance by conjugation to glucuronides and sulphates, which are excreted into the intestine along with bile. The conjugated metabolites can then release free hormones which are reabsorbed, completing enterohepatic circulation of thyroid hormones. Cholestyramine, a bile acid sequestrant, binds to thyroid hormone in the intestine and enhances their clearance. Cholestyramine is usually prescribed as an adjunct to thionamides in patients with refractory thyrotoxicosis. Our experience however demonstrates that in selected patients it may be used as an effective monotherapy when other options are contraindicated or unavailable.

Endocrine Abstracts

CC7