Evening versus Morning Administration of Levothyroxine: a randomised controlled double-blind trial

Hypothyroid patients worldwide are advised to take levothyroxine tablets in the morning half an hour before breakfast. This is because a fiber-enriched diet and ingestion of certain drugs have been shown to have an adverse effect on the intestinal absorption of levothyroxine. In a recent study we showed that TSH significantly decreased and T4 and T3 significantly increased after changing the administration time of levothyroxine from morning to the evening, at bedtime.
We want to perform a large randomised double blind study among patients with hypothyroidism. In this study patients will be asked to take a capsule in the morning as well as in the evening, with one of these capsules containing levothyroxine and the other capsule being a placebo. The patient and his/her doctor will not know which capsule contains the actual levothyroxine. The hospital pharmacist will perform the randomisation. After 3 months the capsules will be switched, so that the capsule containing levothyroxine is taken at a different moment of the day. Every 6 weeks patients will return to the outpatient department for a check-up and bloodtest. At the start of the study and at 3 and 6 months, patients will fill out quality-of-life forms.
Primary endpoint will be a significant change in TSH and FT4/T3 after switching the administration time of levothyroxine to bedtime. Secondary endpoints will be a change in weight, bloodpressure, pulse frequency and change in quality of life.

Administration of levothyroxine at bedtime significantly changes TSH and thyroid hormone levels compared to morning administration. Quality of life will improve with bedtime administration

During the study, patients will have to take 2 tablets a day (one in the morning and one at bedtime), instead of 1 tablet. One of the tablets is levothyroxine, the other placebo. After 3 months the tablets will be switched. During these 24 weeks the patients will return to the outpatient department five times for a check-up, and bloodsamples will be taken