The People's Perspective on Medicine

Beware of Biotin Interfering With Thyroid Tests

Doctors and patients should beware of biotin supplements messing up thyroid test results. To avoid a false diagnosis, a person should stop the biotin first.
Winneconne, WI – 27 May 2019 : A collection of biotin supplements on an isolated background

It’s alarming to get a laboratory test result that shows a serious problem. Learning later that the test might have given a false reading is also frustrating. One reader discovered that you should beware of biotin if you are having thyroid tests run.

Why Should You Beware of Biotin?

Q. My husband recently had blood tests that showed he was hyperthyroid. His doctor ordered further tests, including a thyroid scan and an iodine uptake test.

Then an endocrinologist mentioned that the thyroid blood tests can be affected by biotin. We checked our multi-vitamin, and there were 500 mcg of biotin! Normal RDA is 30 mcg. Others should be warned about this.

Biotin Can Interfere With Tests for TSH:

A. The usual test for thyroid-stimulating hormone (TSH) is subject to interference when biotin levels are high (Nutrition, Jan. 2019).  The result is that TSH appears lower than it actually is, leading to a false diagnosis of hyperthyroidism. When TSH is low, that is an indication that the pituitary gland in the brain is trying to shut down thyroid hormone production. Normally, that would be due to excess thyroid hormone in circulation. But biotin from B vitamins or other products can grab TSH and lower it artificially.

Doctors and patients should both beware of biotin giving a false result on thyroid tests. Patients might be wise not to take biotin-containing products, such as vitamins or hair-restoration products, when they are being tested for thyroid problems.

Learn More:

Biotin is not the only thing that can interfere with blood tests for thyroid function. You can find out about others in our eGuide to Thyroid Hormones.

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About the Author
Terry Graedon, PhD, is a medical anthropologist and co-host of The People’s Pharmacy radio show, co-author of The People’s Pharmacy syndicated newspaper columns and numerous books, and co-founder of The People’s Pharmacy website. Terry taught in the Duke University School of Nursing and was an adjunct assistant professor in the Department of Anthropology. She is a Fellow of the Society of Applied Anthropology. Terry is one of the country's leading authorities on the science behind folk remedies. .
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  • Charles S et al, "Erroneous thyroid diagnosis due to over-the-counter biotin." Nutrition, Jan. 2019. DOI: 10.1016/j.nut.2018.05.005
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About six months ago I started Biotin. The first night my heart beat woke me up. I do have a thyroid problem. I did not put two and two together until the next night when it happened again. It reminded me of when I had hyper-thyroid, and my heart beat the same way. I immediately stopped the Biotin, and the problem stopped.

Yesterday, February 10, 2020, I was informed by my doctor that I should take my over-the-counter supplements five hours AFTER I take my thyroid medication.

I used to take Biotin for better hair and nails. Nothing changed there. However, I started having skipped heart beats. When I stopped the Biotin the skipping stopped.

How long should you stop taking biotin before a thyroid test?

In an article on WebMD — which cites an FDA warning from 11/29/2017 about biotin interference with lab tests — an endocrinologist and medical professor from University of Minnesota says she tells her patients to discontinue supplements one week before lab tests.

Would love to know the publication date of the Thyroid E-Guide. Thanks

Last updated Nov. 2019.

What about Biotin shampoo? I’ve been using Biotin shampoo for years. It has a lot of ingredients besides Biotin, however.

Huh. The only biotin I found in our house is in the shampoo.

I was taking Biotin, and it falsely affected my blood test to show I was hypothyroid. I stopped taking the Biotin, and my hair came in thicker and faster. It is my personal theory that taking Biotin for too long (4 years for me) makes your hair “lazy.” It’s like it says to itself “Why work so hard to grow when you are being given a boost?” I wonder if anyone else has had this experience?

When should you stop the biotin? How many weeks before you get your labs done?

How long should you withhold the biotin before having the lab test drawn?

I am taking 1000mcg Biotin every other day and also taking levothyroxine for low thyroid (which predates my taking Biotin). Had a physical a few weeks ago, and everything tested OK.

What to do now that you are taking thyroid meds after being diagnosed, and you were taking biotin?

How long before taking the thyroid test does a person need to stop the biotin? I take a Super B complex.

I would have been interested in finding out how long before the tests you should stop taking biotin. That would have made the article much more useful to me.

We consulted Dr. R. Bowen, an expert in pathology and clinical chemistry who has investigated this topic. Dr. Bowen points out that the answer depends upon a number of factors: How well do the kidneys work, as this is how the body disposes of biotin? What is the dose of biotin? How well does the individual metabolize biotin? Which test is being used, by which manufacturer?

In many cases, stopping biotin two or three days ahead of the lab visit will work, but it does depend on these factors.

In any event, if you have been taking biotin when you have blood drawn for a hormone test, be sure to tell the technician so that it can be noted. There are some ways that samples can be handled to mitigate the effects of biotin.

We are searching for an answer to this question.

Why is it better to take Synthroid at night?

Either morning or night work fine. For some people, waiting an hour (or at least half an hour) in the morning before having coffee is difficult. For them, taking it at night might work better. Research has shown that it works just as well as taking it in the morning. I myself take my Synthroid at night because I take vitamins with minerals in the morning. Taking the pills at different times of day ensures an adequate separation between them.

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