Certain food, drugs, and gastrointestinal disorders can influence the absorption of your thyroid medication (levothyroxine) which can change your treatment outcomes
The absorption of levothyroxine takes place primary in the gastrointestinal tract. Around 60% to 82% of the administered dose is absorbed during the 3 hours after taking the medicine.
Soybeans and coffee have the greatest impact on the reduction of absorption, whereas vitamin C has the ability to increase it.
Many gastrointestinal disorders, such as celiac disease, atrophic gastritis, lactose intolerance, and Helicobacter pylori infection, may impede the absorption of levothyroxine. During the treatment of these gastrointestinal disorders, the serum TSH and free T4 values should be monitored.
A decrease in the absorption of thyroid medication is established when thyroid medication is taken alongside with:
• cholestyramine (used for chronic liver disease)
• colesevelam (for lowering holesterol and blood sugar)
• lanthanum (kidney disease)
• calcium carbonate (treating too much stomach acid by heartburn, upset stomach, or indigestion)
• calcium citrate (osteoporosis)
• calcium acetate and sevelamer (often used by patients who are on dialysis due to severe kidney disease)
• iron sulfate (anemia)
• ciprofloxacin (part of antibiotics which treat bacterial infections)
• aluminum hydroxide (used by increased stomach acid and certain kidney conditions)
• proton pump inhibitors (medicine addressing the reduction of stomach acid production)
For best absorption of thyroid medication take it 1 hour before breakfast. Separate the intake of thyroid medication from taking the interfering substance.