Short answer: Yes, at high doses. The FDA warns that biotin can interfere with some lab tests and give wrong results that may go unnoticed, including falsely low troponin, a heart attack test. In a study of 6 adults taking 10 mg a day, 9 of 23 biotin-based tests gave wrong results. The Synthroid label says to stop biotin at least 2 days before thyroid tests.
Many lab tests use biotin and a protein called streptavidin, which bind tightly, to capture the substance being measured. The NIH Office of Dietary Supplements (ODS) says very high biotin intakes can interfere with these tests, which are commonly used for hormones such as thyroid hormone and for other markers such as 25-hydroxyvitamin D, giving falsely normal or abnormal results.
The reports involve high-dose supplements: the study ODS describes used 10 mg a day, and the case reports involved 10 to 300 mg a day. ODS does not describe interference from biotin in food.
| Finding | Source |
|---|---|
| 10 mg a day for 7 days in 6 healthy adults: 9 of 23 biotin-based tests (39%) gave wrong results, none of 14 tests without biotin | Li et al. 2017 |
| In that study, 5 of 8 competitive tests read falsely high and 4 of 15 sandwich tests read falsely low | Li et al. 2017 |
| Falsely low TSH and NT-proBNP (a heart failure marker) in the same study | ODS |
| A single 10 mg dose interfered with thyroid tests done within 24 hours | ODS |
| Case reports falsely suggesting Graves' disease in people taking 10 to 300 mg a day | ODS |
| A person taking high-dose biotin died after a troponin test gave a falsely low result | FDA, as cited by ODS |
Interference showed up in some but not all biotin-based tests, and the direction depends on how the test is built, so a result can be wrong in either direction.
The FDA issued a safety communication in 2017 and an update later. Its troponin page says some test makers have reduced biotin interference but others have not, that it keeps receiving reports of falsely low troponin results caused by biotin, and it lists troponin tests that have not addressed the risk.
ODS says the FDA advises health care providers to ask patients about supplements that contain biotin and to consider biotin interference when lab results do not match how the patient looks clinically.
The Synthroid (levothyroxine) label tells prescribers to ask whether patients take biotin or biotin-containing supplements and, if so, to advise stopping at least 2 days before TSH or T4 testing. Other labels and labs may give their own timing.
Biotin is also an ingredient in some multivitamins, so it is worth checking the supplement facts panel for the amount. Telling whoever orders your blood work about any biotin, and when you last took it, lets them judge whether a result could be affected. Dose Track can log supplements with their dose and time, so the last biotin dose before a lab draw is easy to find.
Read more on Dose Track: Biotin guide · TSH (glossary) · Free T4 (glossary) · Synthroid side effects · Multivitamins