Iron, calcium, magnesium, antacids, sucralfate, bile-acid binders such as cholestyramine, and proton pump inhibitors all reduce levothyroxine absorption either by chelation or by altering gastric pH. The standard intervention is temporal separation of at least 4 hours, while keeping levothyroxine on its routine empty-stomach morning schedule. Stopping the thyroid hormone risks profound hypothyroidism and is not appropriate for treating iron deficiency. Crushing levothyroxine is acceptable for swallowing difficulty but mixing it with iron defeats the separation strategy. After a new interacting medication is started, recheck TSH in 6 weeks because absorption changes can shift TSH out of range and require dose adjustment.
For study reference only. Always follow current clinical guidelines and your institution’s protocols.