Although not specifically stated in the labeling for levothyroxine (L-T4), in clinical practice guidelines, coffee is recognized as a compound that may interact with this synthetic hormone used in the treatment of primary or central hypothyroidism. A recent case published in the Journal of the Academy of Nutrition and Dietetics, reports on this interaction in a patient on L-T4 with uncontrolled hypothyroidism likely linked to concurrent consumption of American coffee.

The patient, a 52-year old white woman, presented to a primary care clinic for a regular check-up and to review her type 2 diabetes treatment plan; her medical history included primary hypothyroidism caused by Hashimoto’s thyroiditis, type 2 diabetes mellitus, primary hypertension and morbid obesity. Her list of medicines included:

— Amlodipine 10mg once daily

— Aspirin 81mg once daily

— Atorvastatin 20mg once daily

— Long-acting basal insulin (varied doses) SC at bedtime

— Levothyroxine 175mcg once daily

— Lisinopril 20mg once daily

— Metformin 1000mg twice daily

All medications were taken for at least two years, except for atorvastatin which was started a month earlier; and the patient appeared adherent to her drug regimen. She denied using any over-the-counter drugs, vitamins or dietary/herbal supplements; she was not a smoker and denied alcohol and illicit drug use.