BiotinVitamin B7 · 4 claims

Many immunoassays rely on biotin-streptavidin binding to capture antibodies. Biotin circulating in a patient’s blood competes with that chemistry, so a high supplemental dose can push a result up or down depending on how the particular test is built.

Documented effects include falsely low thyroid stimulating hormone alongside falsely high free T4 and T3 — a pattern that can mimic hyperthyroidism — and false negative hCG results on both blood and urine pregnancy tests.

The threshold matters. Professional guidance states that biotin in over-the-counter multivitamins at doses up to 1 mg has not been reported to cause interference, while doses at or above 5 mg produce concentrations that do. One study found roughly 7% of emergency room patients had circulating biotin above 10 ng/mL.

• RegFDA. Biotin interference with troponin lab tests — assays subject to biotin interference Safety Communications 28 Nov 2017 and 5 Nov 2019
• RevAACC/ADLM guidance document on biotin interference in laboratory tests Doses up to 1 mg not reported to interfere; ≥5 mg does · ~7% of ER patients above 10 ng/mL

Troponin is the biomarker used to diagnose a heart attack. The FDA is specifically concerned about biotin producing a falsely low troponin result, because that leads to a missed diagnosis rather than an unnecessary test. It continues to receive adverse event reports of exactly this.

The 2017 warning followed a case in which a patient taking high-dose biotin died after a potentially falsely low troponin. An important caveat: that interference was never confirmed, and the troponin measurements were taken post-mortem. The pharmacology is solid; the single reported death is weaker evidence than it is usually presented as.

Since 2017 some test manufacturers have fixed their assays and others have not. The FDA now publishes a list of troponin devices still subject to biotin interference, which is an unusual step and a reasonable measure of how seriously it takes this.

• RegFDA listing of troponin in vitro diagnostic devices subject to biotin interference that have not addressed the risk Updated safety communication, 5 November 2019
• RevUC Davis Health laboratory best practice: concerns regarding biotin interference, two years later Notes interference unconfirmed and measurements post-mortem in the index case

The FDA’s position is explicit: sufficient information is not available to know whether stopping biotin for any number of hours before testing will prevent incorrect results.

This is the practical takeaway from the whole page. There is no reliable “skip it for a day” rule you can apply yourself. Tell the laboratory and the requesting doctor that you take it, and let them decide whether the assay they use is affected.

• RegFDA safety communication guidance to consumers and health care providers No established washout interval

Professional laboratory guidance states plainly that biotin in over-the-counter multivitamins at doses up to 1 mg has not been reported to cause immunoassay interference.

The problem is specific to high-dose products — the hair, skin and nail category, and the very high doses that have been trialled in multiple sclerosis. A prenatal or standard multivitamin is a different situation, and it is worth saying so rather than leaving people to assume the worst.

• RevAACC/ADLM guidance on dose thresholds for biotin interference Up to 1 mg not reported to interfere