Effects of Evening vs Morning Levothyroxine Intake. A Randomized Double-blind Crossover Trial
INTEMED. 2010;170(22):1996-2003. doi:10.1001/archinternmed.2010.436

Based on the results of our study, clinicians should inform patients with hypothyroidism that levothyroxine intake at bedtime is a good alternative to levothyroxine intake in the morning, provided that levothyroxine is taken on an empty stomach. For patients who do not attain normal thyrotropin or FT4 levels with morning levothyroxine intake, a switch to bedtime is recommended. Recommendations on timing of levothyroxine intake and on uptake interference by food are found in few guidelines about the management of hypothyroidism. Drug information resources and guidelines require revision in this respect.

In conclusion, bedtime intake of levothyroxine in our study significantly improved thyroid hormone levels. This may be explained by better gastrointestinal bioavailability at night or by less uptake interference by food or medications. As shown in this study, bedtime administration is more convenient for many patients. Clinicians should inform their patients about the possibility of taking levothyroxine at bedtime. A prolonged period of bedtime levothyroxine therapy may be required for a change in QOL (Quality Of Life/red.) to occur.