Background The present study compared the administration of levothyroxine (LT4) before breakfast and bedtime in school children diagnosed with hypothyroidism and analyzed the effects of timing on thyroid functioning and patient satisfaction. Methods A total of 163 children with acquired hypothyroidism (125 females and 38 males) between 8 and 18 years of age and taking LT4 for at least 3 months were enrolled in the study. The timing of administration of the drug of all subjects was shifted to bedtime. The levels of thyroid hormone and blood lipid, anthropometric measurements, Pediatric Quality of Life Inventory, Morisky Medication Adherence Scale and hypothyroidism symptoms scores were analyzed and compared at the beginning of the study and 3 months later after the shift in the timing of drug administration. Results There was no difference between the bedtime and morning regimens of LT4 with respect to thyroid hormone levels, quality of life, drug adherence and symptoms of hypothyroidism. At the end of the study, 45 of 70 new-onset treated subjects preferred the bedtime regimen. Also, drug adherence was found to be better in these patients. Conclusions We found no difference between the bedtime and morning regimens in both new-onset and long-standing treated patients. In naive patients, consideration of patient's preference for timing of drug administration may increase their adherence to medication. Therefore, we suggest that choice of drug administration timing should be based on the preference of patients.
Keywords: drug adherence; hypothyroidism; levothyroxine.