Morning or Bedtime dosing of levo?


l-thyroxine taken at bedtime by patients with primary hypothyroidism is associated with higher thyroid hormone concentrations and lower TSH concentrations compared to the same l-thyroxine dose taken in the morning. At the same time, the circadian TSH rhythm stays intact. Our findings are best explained by a better gastrointestinal uptake of l-thyroxine during the night.

6 Replies

  • That is interesting and good for those who dose at night.

    Not for me though shaws due to sometimes eating too late, sometimes eating too early and then needing a snack before bed, and sometimes crashing out and going to bed really early.

    I always wake early morning and take first thing.


  • How interesting shaws. If they hadn't taken measurements hourly, I'd have wondered if the morning TSH measurement was just depressed by bedtime administration. I wonder by how much the morning measurements of TSH in particular were affected ? Also if measurements at a particular time of day were affected less? Just thinking of timing of blood tests ...

  • Yes because TSH has variations anyway so could be giving a head start.


  • Any thyroid hormone replacement can cause suppressed TSH that includes levo.

  • Thanks Shaws. Nicely summarised conclusion. When I read the report myself I thought it recommended morning dosage until I ploughed through the gobblegook. When I saw my endocrinology yesterday I tried discussing it but he was insistent that morning dosage was best. Reading your blog made me stick with nighttime dosage which I have followed for six months now (after first starting with morning dosage).

  • If the method you use works - why change it! :)

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