Vitamin B7 – biotin – has become highly popular in recent years as a boost to hair, skin and nail strength and fat metabolism. Khloe Kardashian recently declared it her “supervitamin”.
But lab personnel have known for some time that biotin, especially when taken in high doses, can interfere with some laboratory tests. They cause the results of these tests to be either falsely high or falsely low. As a result, people can be misdiagnosed or treated incorrectly. This can have serious consequences.
The affected tests are immunoassays that use biotin in their testing mechanism. These immunoassays use biotin to bind chemicals and other substances in the blood to the test tube so they can be measured. Excess biotin in the blood from supplements can block that binding and the substances are not measured accurately. Depending on the way the assay is constructed, the interference can cause either falsely high or falsely low results.
It is important that anyone taking any biotin-containing supplements stops for at least 48 hours before they have blood taken for testing.
The daily recommended intake of B7 for an adult is 30 micrograms (µg), but many supplements marketed for beauty reasons contain much higher doses, ranging from 5,000 µg to 10,000 µg. Biotin is also being investigated as a possible treatment for diseases. Some new studies suggest that megadoses of biotin (100,000 µg to 300,000 µg) could be used to treat neurodegenerative disorders like multiple sclerosis.
In late 2017, America’s Food and Drug Administration (FDA) published a safety alert to make the public and healthcare practitioners more aware that biotin can "significantly interfere with certain lab tests and cause incorrect test results…" According to the safety alert, there has been "an increase in the number of reported adverse events [injuries associated with medical care], including one death, related to biotin interference with lab tests." The one death occurred when a patient taking high doses of biotin had falsely low troponin results from a troponin test known to have interference from biotin. Troponin
is a biomarker that helps diagnose heart attacks.
Most of the published research on biotin interference covers hormone tests, such as parathyroid hormone (PTH), thyroid stimulating hormone (TSH), T4 and T3 tests, as well as tests for troponin. However, because biotin is used in so many immunoassays, scientists say it could interfere with many others.
It is important to be aware that biotin is found in many over-the-counter supplements in levels that may interfere with laboratory tests. It's not always obvious that a supplement contains biotin—for example, vitamins labeled for healthier hair, nails, and skin may only list biotin as an ingredient on the back label, in small print.
- Examples of supplements include:
- B-complex vitamins
- Coenzyme R
- Dietary supplements for hair, skin, or nail growth
- Prenatal vitamins
- Vitamin B7 supplements
- Vitamin H
If you are taking any supplements you should make sure you discuss them with your doctor before you have any tests. You should also consider the possibility that biotin was the cause of previous test results that don't seem to make sense.