Taking levothyroxine (l-T4) with coffee or with water followed by coffee intake within a few minutes results in poor TSH response in many patients. T4 is available in tablet form worldwide, but novel formulations in soft gel capsule or liquid form are now available.
We fortuitously identified a euthyroid patient who wrongly consumed liquid l-T4 with coffee at breakfast; after changing the time of consumption to 30 min before breakfast, no change in TSH, free T4 (fT4), and free tri-iodothyronine (fT3) concentrations was observed. Once the first patient was identified, additional stable euthyroid patients who consumed liquid l-T4 with coffee were identified.
Patients were recruited by searching our ‘thyroid patients’ database. All the patients on liquid l-T4 treatment were contacted by phone to ask them whether they took l-T4 at breakfast. We identified 54 patients who were submitted to TSH, fT4, and fT3 evaluation, with the indication that the same dosage of l-T4 be consumed 30 min before breakfast. We determined their TSH, fT4, and fT3 concentrations after 3 and 6 months again.
No significant difference in thyroid hormone concentrations was observed in patients when they consumed l-T4 at breakfast or when they consumed it 30 min before breakfast for 3 and 6 months (TSH: 2.5±1.1 vs 2.5±1.1 and 2.4±1.1 mIU/l respectively, fT4: 12.4±2.4 vs 12.5±2.4 and 12.3±2.1 pg/ml respectively, and fT3: 3.4±0.6 vs 3.4±0.6 and 3.3±0.5 pg/ml respectively).
Oral liquid l-T4 formulations could diminish the problem of l-T4 malabsorption caused by coffee when using traditional tablet formulations.