Some of the most frequently observed biotin interferences are with immunoassays for thyroid markers, high-sensitivity cardiac troponin, and N-terminal probrain natriuretic peptide.
JD is a 54-year-old woman who presents to her primary care provider for an annual wellness checkup. She has no complaints, she claims that she has been very diligent with her health and has started taking some new vitamins. JD she reports she took all of her supplements when she did the lab tests, which are illustrated in Figure 1along with your past medical history.
Figure 1. Information on medicines
Biotin is a water-soluble vitamin also known as vitamin H or vitamin B7. It is not naturally synthesized in the body and must be consumed through the diet or via over-the-counter supplements.
It is important to note that most people do not require supplementation and can receive the recommended daily intake of 5 to 35 mcg from foods such as beef, eggs, salmon, pork chops, sunflower seeds, and many other dietary sources.1 Deficiencies are rare, but can occur in people with biotinase deficiency, chronic alcohol exposure, or those who are pregnant or nursing.1
Biotin is commonly marketed for skin, hair, and nail growth, and can be sold in extremely high supplement dosages, such as 10,000 mcg tablets as seen in the case above. It can also be an ingredient in combination tablets such as B complex and multivitamins. Biotin is generally well tolerated and is unlikely to be toxic in high doses due to urinary excretion.
In 2017, the FDA issued a warning that biotin may interfere with laboratory tests. These interactions are seen in biotinylated immunoassays, which are composed of biotin-streptavidin binding.
Some of the most frequently observed biotin interferences are with immunoassays for thyroid markers, high-sensitivity cardiac troponin, and N-terminal probrain natriuretic peptide. For troponins, interference represents a falsely lower value for these markers and alters their predictive value of cardiac function.
Other potential interference includes urine pregnancy tests that test for human chorionic gonadotropin (HCG). These tests are potentially influenced by the falsely portrayed decrease in HCG as well as the increase in urinary excretion of biotin at high doses.
There may be brands of pregnancy tests that have different levels of sensitivity and users should be aware of the need to repeat the test and possibly get invalid results.two Figure 2 illustrates potential laboratory interference with other biotinylated immunoassays, such as cancer markers, drugs, hormones, etc.3.4
Please note that many other interferences are possible, this is not an exhaustive list. Interferences may also differ depending on the laboratory manufacturer, so it is recommended to contact your local laboratory to confirm possible interferences.
Figure 2. Interferences in laboratory tests due to biotin
QUESTION: How does the biotin laboratory’s potential for interference affect pharmacy practice and its role in patient care?
The patient in the above case is taking a high-dose biotin supplement and had worrisome tests. Her low TSH and high T4 could be associated with biotin use, especially if she doesn’t have any symptoms of hypothyroidism.
You should be advised to take biotin before laboratory tests and pregnancy tests, if applicable. In general, it is recommended that pharmacists in all practice settings inquire about the use of supplements and herbal products and effectively document the responses of these patients.
For ambulatory care clinical pharmacists, it may be important to identify biotin-containing supplements and advise patients to discontinue their biotin-containing supplements prior to any scheduled blood tests. The washout period may depend on the patient’s biotin dose and the specific laboratory in question, but it is noted that biotin behaves like a water-soluble vitamin and is excreted from the body within 24 to 48 hours.
In addition, patients should be instructed, in the event of an emergency or hospitalization, to inform their health care team of their recent use of biotin. More information can be obtained by working with the laboratory when a biotin-laboratory interaction is suspected, especially if the results do not correlate with clinical findings.
By observing and understanding these drug-laboratory interactions, pharmacists can help prevent misdiagnosis and improve patient outcomes.
- US Department of Health and Human Services. (North Dakota). Biotin fact sheet for health professionals. NIH Office of Dietary Supplements. Retrieved on July 20, 2022, from https://ods.od.nih.gov/factsheets/Biotin-HealthProfessional/
- Williams, GR, Cervinski, MA, and Nerenz, RD (nd). Evaluation of biotin interference with qualitative point-of-care hcg test devices. Clinical Biochemistry. Retrieved on July 20, 2022, from https://pubmed.ncbi.nlm.nih.gov/29395091/
- Li, D., Ferguson, A., Cervinski, MA, Lynch, KL, and Kyle, PB (2020, Jan 13). AACC Guidance Document on Biotin Interference with Laboratory Tests. Academic of the OUP. Retrieved on July 20, 2022, from https://academic.oup.com/jalm/article/5/3/575/5700349?login=false
- Samarasinghe, S., Meah, F., Singh, V., Basit, A., Emanuele, N., Emanuele, MA, Mazhari, A., and Holmes, EW (2020 Dec 28). Biotin Interference with Routine Clinical Immunoassays: Understanding the Causes and Mitigating the Risks. Endocrine Practice. Retrieved on July 20, 2022, from https://www.sciencedirect.com/science/article/pii/S1530891X20358456