From the Guidelines
Biotin supplements should be stopped at least 2-3 days before thyroid function tests to avoid interference with laboratory results. The potential for biotin to cause falsely high levels of T4 and T3 and falsely low levels of TSH in many common laboratory assays is a significant concern, as it may lead to an incorrect diagnosis of hyperthyroidism or mask hypothyroidism 1. This interference occurs due to the biotin-streptavidin binding technology used in many modern thyroid tests, where excess biotin from supplements competes with the test reagents.
- Key points to consider:
- The effect of biotin on thyroid lab results is dose-dependent, with higher doses causing more significant interference.
- Informing healthcare providers about biotin supplement use is crucial before undergoing thyroid testing.
- Alternative testing methods that are not affected by biotin interference may be recommended by healthcare providers.
- Even with medical conditions like biotinidase deficiency or multiple sclerosis, where biotin is prescribed, it's essential to consult a doctor before stopping the supplement due to the potential impact on thyroid test results.
- It's also important to note that while biotin toxicity is unlikely, with no established upper limit (UL) and no adverse effects shown for oral and IV administration of pharmacological doses up to 5 mg/day for prolonged periods, the primary concern here is the interference with thyroid function tests rather than biotin toxicity itself 1.
From the Research
Biotin Supplement and Thyroid Lab Relation
- Biotin supplements can interfere with thyroid function tests, leading to misleading results 2, 3, 4, 5, 6
- High doses of biotin (10,000 times the recommended daily intake) can cause interference in immunoassays, resulting in abnormal thyroid function tests 2
- Biotin intake can lead to falsely lower TSH and higher free T4 measurements, suggesting hyperthyroidism when no symptoms are present 2, 3, 4
- The interference of biotin with thyroid function tests can be minimized by withholding biotin for a week before testing 2
- Different assay platforms can be affected by biotin interference, including Roche Cobas 6000, Siemens IMMULITE 2000, and Beckman DXI800 analyzer 3, 5, 6
- Biotin interference can lead to significant changes in TSH, fT4, TT3, and Tg measurements, which can be problematic in patients requiring careful titration of levothyroxine therapy 3
- Clinicians should be aware of the potential risk of erroneous test results in subjects taking biotin supplements and consider biotin interference when interpreting thyroid function tests 2, 3, 4, 5, 6
- The duration of biotin interference can vary depending on the dose and assay platform, lasting from 8 hours to 2 days after biotin withdrawal 6