Is Cholestyramine (bile acid sequestrant) effective in treating thyroiditis?

Cholestyramine in Thyroiditis: Efficacy and Recommendations

Cholestyramine is effective as an adjunctive therapy in thyrotoxic thyroiditis, producing more rapid normalization of thyroid hormone levels when combined with standard antithyroid medications. 1, 2

Mechanism and Efficacy in Thyroiditis

• Cholestyramine is a bile acid sequestrant that binds to thyroid hormones in the intestine, increasing their fecal excretion and reducing enterohepatic circulation of thyroid hormones, which is increased in thyrotoxic states 2, 3
• Multiple randomized controlled trials have demonstrated that adding cholestyramine to standard therapy (methimazole and beta-blockers) produces a more rapid decline in thyroid hormone levels than standard therapy alone 1, 4
• In one double-blind placebo-controlled study, patients receiving cholestyramine showed a significantly faster decline in all thyroid hormone levels (p<0.01) compared to the placebo group (p=0.05) 2

Dosing and Administration

• Effective dosing ranges from low-dose regimens (1-2g twice daily) to higher doses (4g four times daily) 1, 2
• Even low doses (2g twice daily) have been shown to be effective and well-tolerated as adjunctive therapy 1
• A prospective randomized trial showed that all patients receiving cholestyramine 2g twice daily with methimazole achieved euthyroid state by the end of a 4-week study period 1

Clinical Response

• Cholestyramine produces a more complete decline in thyroid hormone levels:
  • One study showed 61% reduction in T4, 78% reduction in free T4, and 68% reduction in T3 with cholestyramine plus methimazole, compared to 43%, 65%, and 50% reductions respectively with methimazole alone (p<0.05 for all comparisons) 4
• The greatest efficacy appears to be during the first few weeks of treatment 2, 3
• Case reports demonstrate that cholestyramine can be effective even in cases of refractory hyperthyroidism that fail to respond to conventional high-dose antithyroid medications 5

Adverse Effects and Considerations

• Cholestyramine is generally well-tolerated as an adjunctive therapy in thyroiditis 1, 4
• Common side effects include abdominal bloating, pain, dyspepsia, nausea/vomiting, flatulence, borborygmi, abdominal distension, and constipation 6
• Approximately 11% of patients may find cholestyramine intolerable due to unpalatability or side effects 6
• Cholestyramine can impair the absorption of various medications, including UDCA, and should be administered separately from other drugs 6

Clinical Application

• Cholestyramine is most appropriate as an adjunctive short-term therapy when rapid control of thyroid hormone levels is needed 3
• It should be considered particularly when:
  • First-line antithyroid medications are not adequately controlling severe thyrotoxicosis 3
  • Side effects of high-dose antithyroid drugs are of concern 3
  • Rapid normalization of thyroid function is clinically important 2, 4

Important Considerations

• While cholestyramine has been traditionally recommended as first-line therapy for bile acid diarrhea 6, newer evidence suggests bezafibrate may be preferred for pruritus in cholestatic conditions 6
• When using cholestyramine, it's important to separate administration from other medications to avoid interaction 6
• The therapeutic effect appears to be temporary, with slowing of thyroid hormone decline once cholestyramine is discontinued 4