The Dose of Your Thyroid Medication Can Uncover Your Root Cause


The fact that you’re not absorbing your medication properly could be a hint to the root cause of your thyroid condition.

Dairy Can Be a Problem for Many People with Hashimoto’s

Cow’s milk contains a mix of sugar (lactose), protein (whey and casein) and fat (ghee). People can be sensitive to any of the three components of dairy. However, reactions to lactose and the dairy protein casein are the most common.

Some people with Hashimoto’s may be able to tolerate butter and clarified butter (known as ghee) because they contain very small amounts of dairy proteins, but even tiny amounts of butter caused me to have a reaction at the start of my Hashimoto’s journey.

I’ve written about the dairy protein associated reaction in Hashimoto’s before. Casein, and to a smaller degree, whey, which was a really big trigger for me, and going dairy free resolved three year’s of acid reflux in three days. You can read my Hashimoto’s and dairy story.

But I have not written about the impact of the dairy sugar lactose on Hashimoto’s, and even tiny amounts of it can have a profound impact on our ability to absorb thyroid medications. Worse of all, some thyroid medications actually contain lactose, inhibiting their own absorption!

An August 2014 study published in the Journal of Clinical Endocrinology and Metabolism by Cellini and colleagues found that lactose intolerance increased the requirement for thyroid medications.

The researchers found that the average person with Hashimoto’s required a median dose of 1.31 mcg/kg/day of levothyroxine to get to an average TSH right around 1 mU/L (that would be right around 90 mcg of levothyroxine for a 150 pound person), while a person with Hashimoto’s and lactose intolerance who continued to consume lactose needed a dose of 1.72 mcg/kg/day to reach the same goal (that would be like 116 mcg of levothyroxine for the same 150 pound person- big difference).

Furthermore, patients who had another gut disorder in addition to lactose intolerance required an even higher dose to get to their goal TSH 2.04 mcg/kg/day, or around 140 mcg for a 150-pound person, or 1.5 times the average dose.

2014 study by Asik and colleagues found that lactose intolerant Hashimoto’s patients who were taking levothyroxine showed a decrease in TSH after lactose restriction.

Whenever I see people whose TSH levels fluctuate and who have a hard time adjusting their medication up and down, I always suspect lactose intolerance unless the person is dairy free. I imagine the changes in TSH occur as a result of varying amounts of lactose a person may have on various days.

How Common Is Lactose Intolerance in Hashimoto’s?

Lactose intolerance rates in Caucasians have been reported to be between 7% to 20%, and much higher in people of Asian and African descent. Lactose intolerance can be genetic and permanent, or secondary to another condition and reversible. People with SIBO and Celiac disease are often lactose intolerant when first diagnosed, but once they address SIBO and Celiac disease, many times they find that their ability to tolerate lactose returns after 3-6 months.

A 2006 paper in the journal “Thyroid” described one woman with lactose intolerance and Hashimoto’s, and determined that lactose intolerance was a rare occurrence in causing malabsorption of thyroid medications, however, a newer study, done in 2014 study by Asik and colleagues tested 83 Hashimoto’s patients for lactose intolerance and found lactose intolerance in 75.9% of the patients!

38 of those patients were instructed to start a lactose-free diet for 8 weeks, and the researchers found that over this time, the patients’ TSH dropped, meaning, they were absorbing their thyroid medication better.

So This Lactose Thing Gets Even More Interesting…

For some lactose intolerant people, even tiny amounts of lactose that are found in thyroid medications can be an issue, resulting in impaired absorption of thyroid medications. Yes, thyroid medications could be sabotaging their own absorption if they contain even teeny amounts of lactose.

So if you are someone that can’t get his/her TSH into your sweet spot (TSH should be between 0.5-2 mU/L for most people to feel best) despite taking escalating doses of thyroid medications, consider lactose intolerance and the possibility that the lactose in your diet or even in your thyroid medication may be inhibiting its absorption.

Breaking Down Lactose

As my community is full of extremely smart and motivated people interested in finding solutions, someone is sure to ask… “What about taking Lactaid (a supplement that contains lactase, an enzyme that breaks down lactose) with your thyroid medications? Will that help with the absorption of the medication?

This is a really interesting question… In theory, it should work, but I have not tested that theory yet.  If any of you have had experience with taking Lactaid in conjunction with your lactose containing thyroid medications, I’d love for you to share your experience.

As far as diet, I have personally seen tremendous improvements in my health and the health of clients and readers on a dairy free diet, so this is something that I recommend across the board for people with Hashimoto’s.

Lactose Containing Thyroid Medications

  • Synthroid
  • Euthyrox
  • WP Thyroid
  • Nature-Throid
  • Most generic brands of levothyroxine
  • Some compounded medications- check with your pharmacist

Lactose Free Thyroid Medications

  • Tirosint
  • Armour Thyroid
  • Cytomel***may be cross-contaminated with gluten***
  • Levoxyl
  • Some compounded medications- check with your pharmacist

Medication Tips

Of all of the T4 containing medications, Tirosint has the fewest fillers that may impair absorption, and this medication was specifically designed for this purpose. I’ve had many people on my Facebook page comment on how they felt much better on Tirosint compared to levothyroxine.

Of all of the T4/T3 combination medications, WP Thyroid has the fewest fillers that can impair absorption.

Armour thyroid does not contain lactose but contains corn-derived ingredients that can be problematic in corn sensitive individuals.

Other Factors Contributing to Medication Absorption

A 2012 Polish study by Ruchala and colleagues reported that thyroid patients who need more than 2 mcg/kg/day of levothyroxine with an increased TSH should be suspected of an absorption disorder.

This disorder could be caused by lactose intolerance, celiac disease, atrophic gastritis, H. pylori infection, inflammatory bowel disease, or parasite infection.

Interestingly, in my experience, many of these are also potential root causes of autoimmune thyroid disease and addressing some of these has helped people get into remission.

You can be tested for lactose intolerance, celiac disease, atrophic gastritis or inflammatory bowel disease by most conventional doctors.

For H. pylori and parasite infections, I only recommend working with these specific functional labs: BioHealth Lab, Diagnostic Solutions, and Genova. You would need to have a functional medicine doctor order those tests for your, or you can self-order them (scroll down for more info and resources).

Please note, another study found that 54% of people with hypothyroidism had SIBO, and one of the symptoms of SIBO is lactose intolerance. While this study found that treating SIBO helped the many digestive symptoms experienced by the patients, treatment of SIBO didn’t increase the absorption of thyroid medications.

I wonder if this is because the lactase enzymes do take a few months to regenerate if they do come back at all after treating SIBO, and the participants in the study were not placed on a lactose-restricted diet.

It’s important to find out if you have SIBO because this can be an underlying root cause of Hashimoto’s, and treating the SIBO can not only help your sugar digestive enzymes to regenerate but can also result in remission from Hashimoto’s in some cases. SIBO is a hot new topic in the gut world, so some more progressive doctors may be willing to test you for it. Otherwise, you can self-order a 3-hour lactulose breath test.

Low stomach acid can contribute to poor absorption as well. Some patients take their thyroid medications with a glass of water that includes squeezed lemon juice or a teaspoon of apple cider vinegar. I have had excellent results with using Betaine with Pepsin for low stomach acid.


Figure out your mcg/kg dose of thyroid medication. (Math refresher, take your current dosage of medication, then divide it by your weight in kilograms. To figure out your weight in kilograms, take your weight in pounds and divide it by 2.2.)


If your TSH is around 1, and your dose is 1.31mcg/kg or less: your remaining triggers are likely to be outside of your gut.

If your TSH is >1, and your dose is 1.31mcg or higher: suspect that you have lactose intolerance.

If your dose is 2 mcg/kg or more: consider lactose intolerance + another gut disorder that could be inhibiting your medication absorption and potentially be the root cause of your condition.

**Please note, the TSH is not the only important thyroid test, just the one that was used in research.

Consider testing for lactose intolerance or going lactose free. There’s a good possibility that if you have Hashimoto’s, you also have lactose intolerance. You can either put yourself on a lactose-free diet as a trial or have your doctor do a test for lactose intolerance. If you are someone that needs to see a test to take action (don’t worry, so was I), you can ask your doctor to order a hydrogen breath test for lactose intolerance or a lactose tolerance blood test for you.

Consider having functional medicine tests for the following root causes: SIBO (Small Intestinal Bacterial Overgrowth Breath Test (BioHealth)); parasites and other gut infections (GI-MAP, GI Pathogen Screen 401HGI Effects).




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