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Take Thyroid before bed rather than in the morning
Jacob Schor, ND, FABNO
January 10, 2011
Most doctors have long advised their patients who take thyroid replacement hormone to take it first thing in the morning without food.
It turns out that this is a mistake, or at least seems to be a mistake. A December 2010 paper suggests taking it before bed is more effective.
A number of years ago N. Bolk and colleagues at the Erasmus Medical Centre, Rotterdam, The Netherlands, noticed several patients who appeared to respond better to thyroid hormone administered at night.
They conducted a small pilot study in which they carefully tested thyroid blood values in 12 women who were taking their thyroid in the morning and then switched them to nighttime dosing for two months prior to retesting. Their conclusion, published in 2007, “l-thyroxine [T4] 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.” 
No one believes little pilot studies, especially ones that rock accepted doctrine like this, so they ran a large double blinded placebo controlled crossover study.
From April 2007 to November 2008, they enrolled 105 consecutive patients with primary hypothyroidism. For 6 months patients took a different pill morning and evening, one of which was placebo. After 3 months, the patients witched which pill they took in the morning.
Results of this larger study were published in the December 2010 issue of the Archives of Internal Medicine.
Data from ninety of the patients who completed the trial were analyzed. Taking thyroid at night decreased TSH level by 1.25 mIU/L, increased free T4 level by 0.07 ng/dL and increased total T3 by 6.5 ng/dL. 
Night time dosing seems to be clearly superior. So much so that I am wondering from where this idea of morning dosing originated. No doubt someone will do the necessary homework and tell us the answer in the near future.
There is a potential problem with this. If your TSH is in the 3-5.0 mIU/L range, it should not be a problem. If you have been taking thyroid medication in the morning, and your TSH is in our target range of between 1 and 2 mIU/L and you were to switch to evening dosing, you might need to decrease the amount of medicine you take.
This information should prompt an editorial on our easy assumption that standard medicine is evidence based. Suffice to say, much of what we assume to be based on scientific evidence, is still, more often than not, based on habit, tradition, circumstance and guesswork.
Thyroid test conversion numbers. I need to save these somewhere easy to find, so why not here?
To convert TSH to micrograms per liter, multiply by 1.0; free thyroxine level to picomoles per liter, multiply by 12.871; and total T3 level to nanomoles per liter, multiply by 0.0154.
 Bolk N, Visser TJ, Kalsbeek A, van Domburg RT, Berghout A. Effects of evening vs morning thyroxine ingestion on serum thyroid hormone profiles in hypothyroid patients. Clin Endocrinol (Oxf). 2007 Jan;66(1):43-8.
 Bolk N, Visser TJ, Nijman J, Jongste IJ, Tijssen JG, Berghout A. Effects of evening vs morning levothyroxine intake: a randomized double-blind crossover trial. Arch Intern Med. 2010 Dec 13;170(22):1996-2003.