FDA Safety Communication Standard
Immunoassay Interference
Washout Calculator
Immunoassay Interference
Washout Calculator
Biotin & Thyroid Blood Test Washout Calculator
High-dose biotin (Vitamin B7) in hair, skin, and nail supplements causes profound laboratory interference, creating false low TSH and false high Free T4 blood test results.
Check the supplement facts label on your multivitamin, B-complex, or hair/nail gummy.
Biotin is cleared primarily through renal filtration. Reduced eGFR delays plasma clearance.
Mandatory Biotin Washout Window
American Thyroid Association & Endocrine Society Guideline
Washout Required
Stop 3 Days Before Labs
72-Hour Elimination Clearance Required
Why Biotin Skews Lab Results
Biotin competes with laboratory streptavidin-biotin magnetic bead capture mechanisms in automated immunoassays (Roche, Abbott, Beckman Coulter), causing falsely low TSH and falsely elevated Free T3 / Free T4—mimicking severe hyperthyroidism.