Does Biotin Interfere with Lab Test Results? TSH and Troponin

Short Answer

Yes, high-dose biotin can interfere with some blood tests that use the biotin-streptavidin system. According to TEMD 2025, 5–10 mg of biotin per day can make TSH appear falsely low and free T4 falsely high, leading to a mistaken suspicion of hyperthyroidism. The US FDA has also warned that biotin can make the troponin test appear falsely low and cause a heart attack to be missed. Before giving blood, always tell the laboratory and your doctor that you take biotin.

What is biotin, and how much is needed?

Biotin is also known as vitamin B7. In the body, it helps enzymes involved in fat, carbohydrate and protein metabolism.

The requirement is very small:

Group	Adequate daily intake	Source
Adult	40 µg	TÜBER 2022
Breastfeeding woman	45 µg	TÜBER 2022
Adult (US)	30 µg	NIH ODS
Breastfeeding woman (US)	35 µg	NIH ODS

These values are for healthy people. According to the NIH, biotin deficiency is rare in people with a normal diet. Eggs, organ meats, fish, seeds and nuts are good sources. Avidin in raw egg white blocks the absorption of biotin; cooking inactivates avidin.

The main groups at risk of deficiency are people with biotinidase deficiency, long-term alcohol users, and pregnant and breastfeeding women. Biotinidase deficiency is a congenital disorder, and its treatment is planned by a doctor.

How does it interfere with the test?

Many hormone and cardiac tests measure by attaching biotin-labeled antibodies or antigens to small streptavidin-coated particles. If there is excess free biotin in the sample, it fills streptavidin's binding sites. The test's own biotin-labeled components cannot attach, and the measured signal changes. Depending on the test's design, the result can deviate in two directions.

• Sandwich assays: The result comes out falsely low. TSH, troponin, hCG and PTH are in this group.
• Competitive assays: The result comes out falsely high. Free T4, free T3, testosterone and progesterone are in this group.

The Medical Biochemistry Total Testing Process Guideline (2024) of the Turkish Ministry of Health describes the same mechanism. According to the guideline, the biotin in supplements is far above the recommended daily amount. This is a significant source of error in immunochemical tests.

The problem is not the same in every laboratory. According to the FDA, some test manufacturers have managed to reduce the biotin effect, while others have not yet. Only the laboratory can know which analyzer is affected.

Which tests are affected?

The 2020 guidance of the American Association for Clinical Chemistry (AACC, now ADLM) lists the following among the tests that may be affected:

Test	Possible deviation	Possible misinterpretation
TSH	Falsely low	Hyperthyroidism
Free T4, free T3	Falsely high	Hyperthyroidism, Graves' disease
Troponin	Falsely low	Missed heart attack
hCG	Falsely low	Missed pregnancy or pregnancy complication
PTH	Falsely low	Misinterpretation of parathyroid disease
TSH receptor antibody (TRAb), on some analyzers	Falsely high	Graves' disease

Other hormone tests such as cortisol, prolactin and estradiol may also be affected. According to the FDA's 2017 warning, troponin came out falsely low in a patient taking high-dose biotin, and the patient died. In its 2022 update, the FDA stated that reports of falsely low troponin were continuing.

Vitamin tests can also be affected. According to the AACC table, on some analyzers B12, folate and 25-OH vitamin D can come out falsely high, and ferritin falsely low. The NIH also lists the 25-OH D test among the tests that may be affected. In this case, a true B12 deficiency may appear normal. Whether a test is affected depends on the analyzer.

Biotin is especially confusing in thyroid tests. The findings can mimic Graves' disease; on some analyzers TRAb can also come out falsely positive. In the cases compiled in the AACC guidance, children and adults taking high-dose biotin were mistakenly diagnosed with Graves' disease. TEMD 2025 recommends asking about biotin use in a person who appears thyrotoxic in the laboratory but has no symptoms.

What should you do before the test?

First, check the labels of all the products you use. According to the FDA, biotin can also be present in hair-skin-nail products and multivitamins whose name does not include "biotin."

Sources differ somewhat on the waiting period:

• TEMD 2025 (thyroid tests): Biotin intake should be stopped at least 2 days (48 hours) before the test.
• Turkish Ministry of Health TTP Guideline 2024 and AACC 2020: Those taking 5–10 mg per day should wait at least 8 hours, and those taking 100 mg or more per day should wait 72 hours.

Remember that the period varies with your dose, the type of test and the laboratory's analyzer. According to AACC 2020, this period may be longer in people with impaired kidney function. The best course is to call the laboratory and ask before the test. Stopping biotin should be done only if it is safe for you and your doctor approves. According to the TTP Guideline, biotin is also used therapeutically in some metabolic diseases. If you are taking it on a doctor's recommendation, do not stop it yourself.

In an emergency, there is no waiting. If you have gone to the emergency department with chest pain, say immediately that you take biotin. As the TTP Guideline recommends, the laboratory can measure the sample with another method that is not affected by biotin.

What does the evidence say?

Hair and nails: Biotin is very popular as a hair and nail supplement. However, the evidence is weak. A 2017 systematic review in the journal Skin Appendage Disorders found only 18 cases. In all of these cases, there was an underlying disease or biotin deficiency. According to the authors, there is not enough evidence to support biotin supplementation in healthy people.

The NIH also states that the hair, nail and skin claims are based at most on a few case reports and small studies. Some small studies have reported improvement in brittle nails. These studies are not enough to recommend general use.

Dose and risk: According to the FDA, some hair-skin-nail products contain up to 650 times the daily requirement of biotin. In some products the amount goes up to 20 mg. According to the NIH, even a single 10 mg dose has interfered with thyroid tests performed within 24 hours.

The right approach to hair loss: Finding the cause of hair loss is more useful than random supplementation. Iron deficiency, thyroid disease and hormonal problems can be investigated. For details, see the guide which vitamins are checked in hair loss.

Upper limit and excess

EFSA has not set an upper limit for biotin because of insufficient data. According to the NIH, no toxicity has been seen in patients with biotinidase deficiency with oral intake of up to 200 mg per day. However, the absence of an upper limit does not mean "safe for lab tests." The main risk of biotin is not direct toxicity but a wrong test result and a resulting wrong diagnosis.

Watch out for the hidden-total trap. A hair vitamin, a multivitamin and a B complex may be used at the same time. The biotin in each adds up, and the risk to test results increases.

In Türkiye

• National guideline: The TEMD (Society of Endocrinology and Metabolism of Turkey) Thyroid Diseases Diagnosis and Treatment Guideline 2025 recommends that in biotin users, thyroid tests be ordered after biotin has been stopped for at least 2 days.
• Laboratory guideline: The Turkish Ministry of Health Total Testing Process Guideline (May 2024) lists biotin among pre-analytical sources of error. The guideline notes that over-the-counter use of biotin for hair loss, nail and skin problems is common.
• Health claims: Health claims on supplements are subject to the regulation of TİTCK (Turkish Medicines and Medical Devices Agency) dated April 20, 2023 (Official Gazette No. 32169). The regulation defines a product presented with the claim that it treats or prevents a disease as a "medicinal product for human use." In other words, a biotin product cannot be sold with the claim that it treats hair loss.
• Unexpected result: If a result you see in e-Nabız (Türkiye's national health record app) does not match your symptoms and you take biotin, do not try to treat yourself. Plan a repeat test with your doctor. For details, see the TSH test results guide.

Which doctor should you see?

• If your thyroid tests do not match your symptoms: Endocrinology or Internal Medicine. Mention that you take biotin at the first visit.
• For hair loss or brittle nails: Dermatology. The cause should be investigated before starting a supplement.
• If your pregnancy test result does not match your symptoms: Obstetrics and Gynecology.
• Bring with you: The boxes of all the supplements you use, your latest test results and the time of your last biotin dose.

When should you seek emergency care?

• Chest pain, pain spreading to the left arm or jaw, cold sweats: call 112 (the emergency number in Türkiye) immediately. Tell the team that you take biotin; do not let a normal troponin result delay you.
• Sudden shortness of breath or fainting: call 112.
• Severe groin pain or vaginal bleeding when pregnancy is suspected: go to the emergency department without waiting, whatever the test result. If you faint or feel dizzy, call 112.
• Real symptoms of hyperthyroidism such as palpitations, weight loss and tremor: see a doctor the same day; report your biotin use.
• If a child has swallowed a product containing iron, call 112 without waiting for symptoms. If they have swallowed another supplement, call 114, the National Poison Information Center; if there is drowsiness, vomiting, breathing difficulty or seizures, call 112.

Related guides

• Vitamin and Mineral Guide
• Lab test interpreter
• Thyroid tests: TSH, T3, T4, anti-TPO
• What does high troponin mean?
• Beta-hCG levels
• High parathyroid hormone (PTH)
• How to read a supplement label

What changed? (October 2026)

• The biotin recommendation of the TEMD 2025 thyroid guideline (at least a 2-day interval) and the waiting periods of the Turkish Ministry of Health TTP Guideline 2024 were presented together.
• The FDA's 2017 warning and 2022 troponin update were used as the basis.
• How biotin interferes with tests was explained more accurately. False-positive TRAb mimicking Graves' disease and deviations in vitamin tests were added. The biotin requirement was given according to TÜBER 2022.

Sources

• Türkiye Endokrinoloji ve Metabolizma Derneği. Tiroid Hastalıkları Tanı ve Tedavi Kılavuzu 2025. https://file.temd.org.tr/Uploads/publications/guides/documents/tiroid2025_11042025.pdf (accessed October 4, 2026)
• T.C. Sağlık Bakanlığı SHGM. Tıbbi Biyokimya Toplam Test Süreci Rehberi. Publication No. 1287, May 2024. https://dosyamerkez.saglik.gov.tr/Eklenti/48692/0/tibbi-biyokimya-toplam-test-sureci-rehberipdf.pdf (accessed October 4, 2026)
• Sağlık Bakanlığı. Türkiye Beslenme Rehberi (TÜBER) 2022. https://hsgm.saglik.gov.tr/depo/birimler/saglikli-beslenme-ve-hareketli-hayat-db/Dokumanlar/Rehberler/Turkiye_Beslenme_Rehber_TUBER_2022_min.pdf (accessed October 4, 2026)
• TİTCK. Gıda ve Takviye Edici Gıdalarda Sağlık Beyanı Kullanımı Hakkında Yönetmelik. Resmî Gazete 20.04.2023, No. 32169. https://www.resmigazete.gov.tr/eskiler/2023/04/20230420-5.htm (accessed October 4, 2026)
• U.S. FDA. Biotin Interference with Troponin Lab Tests – Assays Subject to Biotin Interference. Updated June 21, 2022. https://www.fda.gov/medical-devices/in-vitro-diagnostics/biotin-interference-troponin-lab-tests-assays-subject-biotin-interference (accessed October 4, 2026)
• U.S. FDA. The FDA Warns that Biotin May Interfere with Lab Tests: FDA Safety Communication. November 28, 2017 (FDA docket copy). https://downloads.regulations.gov/FDA-2019-D-1876-0005/content.pdf (accessed October 4, 2026)
• Li D, Ferguson A, Cervinski MA, Lynch KL, Kyle PB. AACC Guidance Document on Biotin Interference in Laboratory Tests. 2020. https://myadlm.org/science-and-research/academy-guidance/biotin-interference-in-laboratory-tests (accessed October 4, 2026)
• NIH Office of Dietary Supplements. Biotin: Fact Sheet for Health Professionals. Updated January 10, 2022. https://ods.od.nih.gov/factsheets/Biotin-HealthProfessional/ (accessed October 4, 2026)
• EFSA. Overview on Tolerable Upper Intake Levels as derived by the SCF and the EFSA NDA Panel. Version 11, August 2025. https://www.efsa.europa.eu/sites/default/files/2024-05/ul-summary-report.pdf (accessed October 4, 2026)
• Patel DP, Swink SM, Castelo-Soccio L. A Review of the Use of Biotin for Hair Loss. Skin Appendage Disord 2017;3(3):166-169. https://doi.org/10.1159/000462981 (accessed October 4, 2026)