Case Study: Impact of Biotin Lab Interferences in Clinical Practice
Some of the most frequently noted biotin interferences are with immunoassays for thyroid markers, high-sensitivity cardiac troponin, and N-terminal pro-brain natriuretic peptide.
JD is a 54-year-old female who presents to her primary care provider for an annual wellness check. She has no complaints, states that she has been very diligent about her health, and has started a few new vitamins. JD reports taking all her supplements when her labs were drawn, both of which are illustrated in Figure 1, along with her past medical history.
Figure 1. Medication information
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 either through diet or OTC supplementation.
It is important to note that most people do not require supplementation and can receive the recommended daily intake of 5-35 mcg from foods such as beef, egg, salmon, pork chop, sunflower seeds, and many other dietary sources.1 Deficiencies are rare but can occur in individuals with a biotinase deficiency, chronic alcohol exposure, or those who are pregnant or breastfeeding.1
Biotin is commonly marketed for skin, hair, and nail growth, and may be sold at extremely high supplementation doses, such as 10,000 mcg tablets as seen in the above case. It may also be an ingredient in combination tablets such as B complex and multivitamins. Biotin is usually well tolerated and unlikely to be toxic at high doses due to urine 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 noted biotin interferences are with immunoassays for thyroid markers, high-sensitivity cardiac troponin, and N-terminal pro-brain natriuretic peptide. For troponins, the interference portrays a falsely lower value for these markers and disrupts its predictive value of cardiac function.
Another potential interference includes urinary pregnancy tests that look at 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 sensitivity levels and users should be aware of the need for repeat testing and possibly invalid test results.2 Figure 2 illustrates the potential lab interferences with other biotinylated immunoassays such as markers for cancer, drugs, hormones, etc.3,4
Be aware that many other interferences are possible, this is not an exhaustive list. Interferences may also differ by manufacturer of lab therefore it is recommended to contact the local laboratory to confirm potential interferences.
Figure 2. Lab test interferences due to biotin
QUESTION: How does the potential for biotin lab interference affect pharmacy practice and its role in patient care?
The patient in the above case is taking a high dosed biotin supplement and had tests of concern. Her low TSH and high T4 could be associated with biotin use, especially if she does not have any symptoms of hypothyroidism.
She should be counseled to hold biotin prior to labs as well as pregnancy tests, if applicable. In general, it is recommended that pharmacists in all practice settings ask about the use of supplements and herbal products and effectively document these patient responses.
For ambulatory care clinical pharmacists, it may be important to identify biotin-containing supplements and to counsel patients to hold their biotin-containing supplements prior to any scheduled bloodwork. The washout period may depend on patient’s biotin dose and the specific lab of concern, but biotin is noted to behave as a water-soluble vitamin and be excreted from the body within 24-48 hours.
Also, patients should be instructed that in the case of an emergency or inpatient stay, they inform their health care team on their recent biotin usage. Further information may be gained from working with the lab when a biotin-lab interaction is suspected, especially if results do not correlate with clinical findings.
By noting and being aware of these drug-lab interactions, pharmacists can help prevent incorrect diagnoses and improve patient outcomes.
- U.S. Department of Health and Human Services. (n.d.). Biotin- Health Professional Fact Sheet. NIH Office of Dietary Supplements. Retrieved July 20, 2022, from https://ods.od.nih.gov/factsheets/Biotin-HealthProfessional/
- Williams, G. R., Cervinski, M. A., & Nerenz, R. D. (n.d.). Assessment of biotin interference with qualitative point-of-care hcg test devices. Clinical biochemistry. Retrieved July 20, 2022, from https://pubmed.ncbi.nlm.nih.gov/29395091/
- Li, D., Ferguson, A., Cervinski, M. A., Lynch, K. L., & Kyle, P. B. (2020, January 13). AACC guidance document on biotin interference in laboratory tests. OUP Academic. Retrieved 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, M. A., Mazhari, A., & Holmes, E. W. (2020, December 28). Biotin interference with routine clinical immunoassays: Understand the causes and mitigate the risks. Endocrine Practice. Retrieved July 20, 2022, from https://www.sciencedirect.com/science/article/pii/S1530891X20358456