Published on September 16, 2021

Video Friday: Must-know information about biotin… Have you received a higher vitamin D result from another lab? This could be why.

Key Points

  • Supplemental biotin may interfere with certain immunoassay lab tests, leading to falsely high or falsely low results
  • Tests affected include troponin (used to help diagnose heart attacks), certain hormone assays, certain cancer assays, and vitamin D levels
  • None of the tests offered by GrassrootsHealth are affected by biotin interference, however, many of these tests run through doctors and hospitals are affected
  • It is essential to know if you take biotin and how much, and to let your health care providers know in case of the need for lab testing

In 2017, the U.S. Food and Drug Administration (FDA) issued a safety warning to the public, and to doctors and laboratories, that biotin (vitamin B7) could interfere with certain laboratory tests, leading to falsely high or falsely low results.

While this does not affect any of the laboratory tests offered by GrassrootsHealth, we wanted to make our participants aware of the issue, as it may affect vitamin D results coming from another laboratory source, such as those from your doctor or hospital visit.

What Types of Laboratory Tests can be Affected by Biotin?

A type of laboratory test called an immunoassay can often be affected by excess biotin in the blood (either from a biotin supplement or from a B-complex), as many of these tests use biotin as part of its testing method. Unfortunately, immunoassays are one of the most common types of testing methods used by doctors and hospitals.

Examples of tests that can be affected by biotin include tests for:

  • Troponin (a test used to help diagnose heart attacks)
  • Thyroid hormone tests, such as thyroid stimulating hormone (TSH), thyroxine (T4) and triiodothyronine (T3) tests
  • Other hormones, such as parathyroid hormone (PTH), cortisol, follicle -stimulating hormone (FSH) and luteinizing hormone, as well as reproductive hormones such as testosterone
  • Cancer assays, such as prostate-specific antigen (PSA)
  • Vitamin D levels

When testing vitamin D levels using these immunoassays, biotin interference can cause a falsely high result. This has been known to create confusion for participants when testing their vitamin D levels through GrassrootsHealth and another lab (such as through their doctor) around the same time.

Does Biotin Affect Any of the GrassrootsHealth Tests?

None of the testing methods use for the tests offered by GrassrootsHealth are affected by biotin. For vitamin D specifically, the testing method used is called LC-MS/MS (liquid chromatography – mass spectrometry), which is considered the gold standard for 25(OH)D testing. (see below for more on the lab testing used by GrassrootsHealth)

Learn More with this Video: Impact of Biotin Interference in Lab Tests

The following video is by Tosoh Bioscience, a company that provides clinical diagnostic systems to doctors, hospitals, and laboratories. They give an excellent description of what biotin interference is and what tests it can affect. Watch the video, and take note of the summary below.

Watch Now

  • Biotin (vitamin B7) is found in foods such as eggs, fish, seeds
  • The average daily recommended amount of biotin ranges up to 35 mcg per day, which can easily be obtained through the diet
  • Supplements such as B-complex vitamins, multivitamins, prenatal vitamins, and those specifically for hair, skin and nails, can provide larger amounts of biotin, with some containing up to 5000-10,000 mcg biotin/day
  • When planning on getting laboratory testing done, it is necessary to refrain from taking biotin supplements for 8 hours to several days before testing – how quickly biotin is cleared from your blood depends on the dose taken and on the health of the kidneys
  • Notify your health care provider of biotin supplementation if testing is to be done
  • Not all lab tests are designed the same, and so not all will be affected by biotin; regardless, it is important to know if you are taking biotin and how much

Additional Information About Vitamin D and Other Tests Through GrassrootsHealth

GrassrootsHealth uses ZRT Laboratory for our vitamin D tests. Key considerations are that they are CLIA (Clinical Laboratory Improvement Amendments) certified, which ensures the lab conforms to federal regulations regarding testing, and that they participate in DEQAS, the Vitamin D Quality Assessment Scheme, which provides control samples to ensure assay accuracy. The blood spot assay is performed using LC-MS/MS, the gold standard in 25(OH)D testing. Validation tests against serum blood draws done at the same time as blood spot collection has shown a high level of agreement between the two testing methods – this document from ZRT gives more information.

Other tests run by ZRT Laboratory and not affected by biotin interference include the magnesium test, essential and toxic elements panel, hs-CRP, HbA1c, and thyroid stimulating hormone (TSH).

Remember to Check Important Co-Nutrients as Well

Having and maintaining healthy vitamin D levels and other nutrient levels can help improve your health now and for your future. Choose which to measure, such as your vitamin D, omega-3s, and essential minerals including magnesium and zinc, by creating your custom home test kit today. Take steps to improve the status of each of these measurements to benefit your overall health. You can also track your own intakes, symptoms and results to see what works best for YOU.

Enroll and test your levels today, learn what steps to take to improve your status of vitamin D (see below) and other nutrients and blood markers, and take action! By enrolling in the GrassrootsHealth projects, you are not only contributing valuable information to everyone, you are also gaining knowledge about how you could improve your own health through measuring and tracking your nutrient status, and educating yourself on how to improve it.

Help everyone Move Research into Practice with vitamin D and other nutrients! As a special birthday gift to everyone, in honor of the science, we have created a special scholarship fund for anyone to donate to that will go towards helping others participate. Your donation will allow anyone to get help with funding their participation when they need it.

Text-to-give: Text Daction to 44321 to add to our Scholarship Fund.

What Does it Take YOU to Get Your D to 40 ng/ml (100 nmol/L)?

Did you know your health could be greatly affected by making sure you have a vitamin D level of at least 40 ng/ml (100 nmol/L)? Help us help you.

STEP 1 - Do you know what your vitamin D level is? If not, be sure to test today to find out.

STEP 2 – Determine your target level. Are you at your target level? Experts recommend a level of at least 40-60 ng/ml (100-150 nmol/L).

STEP 3 – Need to boost your level? Use the D*calculator to see how much vitamin D it may take to reach your target. Opt for the Loading Dose for a quicker boost.

STEP 4 – Optimize how your body absorbs and utilizes vitamin D with co-nutrients and these simple steps.

STEP 5 – Re-Test! This is an important step to make sure you have reached your target level, and to ensure you are not taking too much! Re-testing after 3-4 months is recommended.

STEP 6 – Adjust, Repeat…

Give your immune system the nutrients it needs to support a healthy you and protect yourself from unnecessary diseases, especially COVID-19.


The first Randomized Controlled Trial on vitamin D and COVID-19 has shown a 96% lower risk of ICU admission for those receiving vitamin D (as 25(OH)D to quickly boost vitamin D blood levels) along with the standard treatment, compared to those receiving standard treatment alone.

These results support many previous observational studies showing a relationship between vitamin D levels and intake and COVID-19 severity.

Review the Latest Nutrient Research for COVID-19

GrassrootsHealth Nutrient Research Institute has launched the new Immune Boost project with the use of our myData-myAnswers nutrient health system that nearly 15,000 people are already using for their health. Specific markers that influence immune health are suggested for testing as part of this project including:

  • Vitamin D
  • Omega-3 Index
  • Essential elements magnesium, selenium, and zinc
  • hsCRP

Our goal is to demonstrate how one can use the Nutrient Research Model established by Dr. Robert Heaney to show the effect of vitamin D serum levels of at least 40 ng/ml (100 nmol/L) on risk reduction for all ethnicities in the population. Status and intake of other nutrients will also be analyzed for any type of relationship to immune status and symptom severity. Join the project today!

Please let us know if you're interested in helping sponsor this project.

CLICK HERE for updates and new information about the project.

Through GrassrootsHealth Nutrient Research Institute, you can also test your essential elements magnesium, copper, zinc and selenium, toxins such as lead, mercury and cadmium, as well as your omega-3 levels, inflammation levels and thyroid stimulating hormone (TSH) level. Find out your levels today! Log on to the test selection page (click the link below) to get your tests and see for yourself if your levels can be improved.

Make sure you track your results before and after, about every 6 months!

Click Here to Access the Test Page

How can I track my nutrient intake and levels over time?

To help you track your supplement use and nutrient levels, GrassrootsHealth has created the Personal Health Nutrient Decision System called

For each specific supplement, you can track what days you take it, how much, and many other details.  This will help you know your true supplemental intake and what patterns of use work for you to reach and maintain optimum nutrient levels. Check it out today!