When Should I Take Thyroid Medication?

When Should I Take Thyroid Medication? I get this question asked a lot because of the difficulty often-times of taking Synthroid, Levothyroxine or Armour first thing in the morning and then having to wait 45-90 minutes before consuming anything else, even other prescriptions or supplements. I decided to do a good bit of research to identify the underlying reason why medical doctors, particularly our endocrinologists, recommend taking the medications in the morning.The main reason appears to avoid trouble falling asleep, as for some people thyroid medication can cause trouble with sleep. This is likely because of the relationship between the adrenal hormone cortisol and the Hypothalamus-Pituitary Axis which regulates all hormones in the body, including TSH.

Mechanically, levothyroxine and Synthroid works no differently in the presence of food as in its absence. What changes is how much of the drug is absorbed with some published studies showing about a 20% drop if Synthroid is taken with food, compared to an empty stomach.

Of interest is that two important studies published in medical journals have found that taking the same dose of thyroid medication at bedtime may actually be better than taking it first thing in the morning. A 2007 study published in the journal Clinical Endocrinology, and a follow-up larger randomized trial reported in the December 2010 issue of the Archives of Internal Medicine both showed this response.

The studies were prompted by observation that some patients had improved thyroid hormone profiles after they switched from taking their levothyroxine in the morning to bedtime. Not only did they evaluate the impact of thyroid hormone levels by changing the time of medication, they also evaluated the impact this had on TSH and thyroid hormones and thyroid hormone metabolism. The studies were fairly conclusive in their findings, which the researchers said were "striking" and which have "important consequences for the millions of patients who take levothyroxine daily."

Researchers reported that taking medication at bedtime, rather than the morning, results in "higher thyroid hormone concentrations and lower TSH concentrations." TSH decreased and Free T4 levels rose in all patients by changing T4 ingestion from early morning to bedtime and T3 levels rose in all but one subject. And TSH decreased irrespective of the starting TSH levels, suggesting better absorption of the thyroid medication when taken in the evening. Interestingly, the researchers found that the circadian TSH rhythm -- the typical daily fluctuations of TSH that occur during a 24-hour period - actually did not vary.

The researchers suggested several explanations for the improved results:

  • Even when waiting at least 30 minutes to eat, breakfast may be interfering with the intestinal absorption of levothyroxine.
  • Bowel motility is slower at night, which means that it takes longer for the levothyroxine tablet to transit through the intestinal system, resulting in longer exposure to the intestinal wall, and therefore, better uptake of the medication.
  • The conversion process of T4 to T3 may be more effective in the evening.

The researchers found that the patients taking nighttime levothyroxine had a drop in TSH of 1.25 -- which is a significant change. The free thyroxine (Free T4) level went up by 0.07 ng/dL, and total triiodothyronine (Total T3) went up by 6.5 ng/dL. According to the researchers, there were no significant changes in the other factors. The researchers in both studies concluded that, given the improvement in thyroid hormone levels, physicians should consider prescribing levothyroxine to be taken at bedtime.

With this research published, I feel the following major implications exist for many of our patients.

do you need supplements copyFirst, it's easier, as you don't have to worry about when to eat breakfast. Second, it's easier to take your supplements, foods and medication including calcium and iron that can interfere with thyroid medication absorption. For those with blood sugar problems, especially my patients with reactive hypoglycemia (low blood sugar), this would make it tremendously easier in the morning to get your day started. Fourth, it might offer some improvement in symptoms to people who are just not getting optimal absorption by taking thyroid medication during the day.

While these only represent a few studies, they confirm what many patients have been reporting for years -- that they feel better if they take their thyroid medication in the evening, rather than the morning.

I do not advocate you switch on your own, but would absolutely recommend you tell your health care practitioner who prescribed your thyroid hormone that you want to try changing the time you take your prescription to bedtime, versus morning. And if you decide to change to taking your thyroid medication in the evening, make sure we check your thyroid levels via blood test in six to eight weeks to help us to determine if you need to adjust the dosage or timing of your medication.

I do need to caution those of you on Armour, NatureThroid or other T3 based thyroid-hormone replacement medications. This research was not done on T3 but only T4 and so we simply don't know if the results will be the same. I am not opposed to you trying the same thing we are advocating, but keep in mind sleep quality could be impacted in some patients.