Biotin can interfere with some laboratory immunoassays, producing misleading results.
The published requirement is to avoid non-prescribed Biotin supplements for 48 hours, or two days, before collection. Check multivitamins and products marketed for hair, skin and nails, which may contain it.
If Biotin is prescribed, do not stop it without discussing the plan with the prescribing clinician. Tell the provider about all supplements, including the dose and most recent use. If the pause has not been possible, disclose that before relying on the result.
Thyroid tests, AMH and other hormone assays can be affected, depending on the method.