Levothyroxine Interactions and More and More

Levothyroxine absorption is highly vulnerable to gastrointestinal disruptions and concurrent ingestions. Common culprits include calcium carbonate, ferrous sulfate, proton pump inhibitors, and fiber supplements, which bind the hormone or alter gastric pH. Co-administered agents or malabsorptive states necessitate strategic spacing of at least four hours or dosage recalibration based on free thyroxine and thyrotropin monitoring. Clinicians must systematically screen for dietary and pharmacological interferences before pursuing extensive workups for apparent refractory hypothyroidism.