New recommendations from the AACC Academy, published in the Journal of Applied Laboratory Medicine, suggest ways to prevent, identify, and deal with biotin interference in some types of laboratory tests.
Biotin—also known as vitamin B7, vitamin H, and coenzyme R—is a nutrient the body requires in very small amounts for turning fat, protein, and carbohydrates from food into energy. Biotin also helps the body to produce hormones. Foods such as meat, fish, eggs, seeds, nuts, and certain vegetables naturally contain biotin. The average daily recommended amount of biotin for healthy adults is 30 micrograms (mcg) per day.
Some people take supplements containing higher doses of biotin (for example, more than 5,000 mcg) because they believe it will help improve the condition of their hair, nails, and skin. Some patients may be treated with biotin mega-doses of 100,000 mcg or more because new research suggests such doses may be helpful in treating certain medical conditions, such as multiple sclerosis.
Individuals who regularly take more than 5,000 mcg of biotin per day may have an excess amount in their blood, which can interfere with some types of laboratory tests called immunoassays. This is because some immunoassays use biotin as part of the reagent mixture in the testing method. Excess biotin in the blood from supplements may cause either falsely increased or falsely decreased results, depending on the test. Inaccurate results may lead healthcare practitioners to misdiagnose patients and/or prescribe inappropriate treatments. The risk of adverse events due to biotin interference prompted a 2017 Food and Drug Administration (FDA) warning.
The new guideline cites research that shows that the degree of biotin interference depends on the amount of biotin in the blood sample. For individuals who do not take biotin-containing supplements, the amount of biotin that comes from the diet is too low to interfere with bloods tests. Similarly, the amount of biotin from taking over-the-counter multivitamins (doses up to 1,000 mcg) has not been reported to cause interference.
Research also shows that different manufacturers’ tests that measure the same substance may exhibit different degrees of biotin interference. Some common immunoassays that may be affected include those for:
The guideline suggests several ways labs can verify suspected biotin interference. Labs and healthcare practitioners should communicate when results don't seem to make sense and they may request that a new blood sample be collected after the patient has discontinued use of biotin for the appropriate amount of time, as indicated by the test manufacturer.
Based on studies showing how quickly biotin is cleared from the blood, people who have consumed 5,000–10,000 mcg biotin need to wait a minimum of 8 hours after the last dose before having blood collected for laboratory tests. Waiting up to 72 hours may be required to prevent interference with some immunoassays. Patients who are on high-dose biotin therapy (100,000 mcg/day or more) should talk to their healthcare practitioner before blood collection. Since biotin is cleared from the blood by the kidneys, people with kidney dysfunction or kidney disease may need to refrain from taking biotin for a longer period.
The guideline recommends ways in which healthcare practitioners, laboratory personnel, and lab test manufacturers can work together and improve communications about biotin interference.
- Laboratories should determine which tests may be affected by biotin interference and educate healthcare practitioners about the findings.
- Labs can also raise consumer awareness of the issue by placing placards about potential biotin interference in outpatient blood collection centers.
- Healthcare systems should include questions about the use of biotin and nutritional supplements in inpatient and outpatient registration processes. Systems may also update electronic health records to display alerts when practitioners order tests with known biotin interference problems.
- Healthcare practitioners should ask patients whether they use biotin-containing supplements. Practitioners should also contact the laboratory when results do not fit the patient’s clinical picture or if the patient is known to have taken biotin.
The FDA's safety communication provides recommendations for consumers. These include telling your healthcare practitioner if you take or plan to take biotin or a supplement containing biotin and alerting your healthcare practitioner if you are concerned about test results and the possibility of biotin interference. The FDA emphasizes the importance of knowing exactly what supplements contain. It is not always obvious that biotin is an ingredient. Supplements labeled for healthier hair, nails, and skin may only list biotin as an ingredient on the back label, in small print, the FDA notes.
Some lab test manufacturers have been working to reformulate their tests so that they are not affected by excess biotin. However, since development and FDA approval of new tests can take time, biotin inference may remain an issue for years to come.