Reminder: Biotin Can Alter Lab Results

 In Naturopathic News

Node Smith, ND

In a case report published in the Journal of the Endocrine Society, we are reminded to be mindful of how supplementation of certain vitamins and minerals may alter lab results.1 The specific case study shows how a patient taking a biotin supplement was led down a rabbit hole of various consultations and unnecessary testing due to clinically misleading blood work caused by the biotin.

Biotin known to impact lab values, especially hormone tests

Biotin, vitamin B7, is a commonly consumed supplement. It is marketed to the general public for healthy skin, hair and nails, and routinely put into anti-aging products and multi-vitamin formulations (especially formulas that concentrate on hair/skin/nails). There is no need for a prescription, and it is relatively inexpensive. Biotin is generally safe, however it is known to impact certain lab values, especially hormone tests. The reason for this is because many lab tests actually utilize biotin as part of the testing process, so introducing additional biotin falsely impacts the test results.

Case study: Lab results came back with cortisol and testosterone levels indicative of hormone producing tumor

The patient in the case report took a daily supplement containing 5000 mcg of biotin (or 5 mg). This amount is common in many formulations which may range from 2000 mcg (2 mg) to 10,000 mcg (10 mg). In this patient’s case her lab results came back indicating cortisol and testosterone levels that were indicative of a hormone producing tumor – hypercortisolemia and elevated testosterone. The abnormal test results resulted in many invasive tests and procedures that were ultimately unnecessary.

Study doesn’t discourage use of biotin

The case study is not intended to discourage the use of biotin as a supplement, but to bring awareness to the impact the vitamin may have on test results if/when they are needed.

Biotin altered lab tests can render both positive and negative results

Not all of the lab tests altered by biotin are in the positive either. Some tests, such as troponin – a common test used to determine if someone has recently had a heart attack – can be falsely decreased by biotin in the blood. This means that a heart attack could be missed due to a false low troponin level; and this has happened. Other tests which can be altered are tests for cancer markers, pregnancy, anemia, and thyroid – Grave’s disease has been misdiagnosed in children and adults due to falsely elevated thyroid hormone.

Biotin not the only supplement to alter lab values

Some doctors have initiated the practice of asking patients to discontinue vitamin supplements for 1 week prior to having blood work, if possible, especially if these supplements contain biotin. However, biotin is not the only supplement that alters lab values. Perhaps the most well-known interaction is with vitamin C, which has long been known to falsely elevate blood glucose readings. When possible, it may be worthwhile to consider discontinuing certain supplements before conducting laboratory studies. And certainly important for both patients and doctors to be clear about what supplements are being taken when considering lab values.


  1. Heather M Stieglitz, Nichole Korpi-Steiner, Brooke Katzman, Jennifer E Mersereau, Maya Styner. Suspected Testosterone-Producing Tumor in a Patient Taking Biotin Supplements. Journal of the Endocrine Society, 2018; DOI: 10.1210/js.2018-00069
Image Copyright: <a href=’’>fahroni / 123RF Stock Photo</a>

Node Smith, ND, is a naturopathic physician in Portland, OR and associate editor for NDNR. He has been instrumental in maintaining a firm connection to the philosophy and heritage of naturopathic medicine among the next generation of docs. He helped found the first multi-generational experiential retreat, which brings elders, alumni, and students together for a weekend camp-out where naturopathic medicine and medical philosophy are experienced in nature. Four years ago he helped found the non-profit, Association for Naturopathic ReVitalization (ANR), for which he serves as the board chairman. ANR has a mission to inspire health practitioners to embody the naturopathic principles through experiential education. Node also has a firm belief that the next era of naturopathic medicine will see a resurgence of in-patient facilities which use fasting, earthing, hydrotherapy and homeopathy to bring people back from chronic diseases of modern living; he is involved in numerous conversations and projects to bring about this vision.

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