Millions of people have an underactive thyroid gland. This is called hypothyroidism and is usually treated with synthetic thyroid hormone called levothyroxine. There has been controversy about the best time of day to take this medication.
To determine whether it makes a difference whether the drug is taken upon arising or at bedtime, 105 Dutch patients were randomized to take one capsule in the morning and one in the evening. One was levothyroxine and the other was placebo, but neither the patients nor the doctors knew which was which. After 3 months the patients were switched.
When the code was broken, the investigators found that the measures of thyroid function in the blood improved with bedtime administration. Patients also reported feeling better. According to the scientists, “clinicians should consider prescribing levothyroxine intake at bedtime.” [Archives of Internal Medicine, Dec. 13/27, 2010]