This simple and small scale study demonstrated that even a single dose of 10 milligrams of biotin is enough to push TSH down, and FT4 and FT3 up sufficiently to potentially cause misdiagnosis.
10 milligrams was chosen because it is commonly available dose of biotin as a supplement. Anyone could take that single dose and never suspect any impact. That could leave them undiagnosed, wrongly diagnosed or inappropriately dosed.
Currently trials of biotin for multiple sclerosis are ongoing which use 300 milligrams of a form of biotin (said to be highly concentrated). Goodness knows what impact that could have on TSH, FT4 and FT3 tests!
Also, though this study focussed on these three thyroid tests, several other blood tests are also believed to be susceptible to the impact of biotin.
Thankfully, leaving off biotin for 24 hours was sufficient to get these tests back to where they should be. It might take longer for those taking higher doses, or taking biotin over a longer period, to see the impact dissipate - but I don't know how long. Others have suggested a few days.
I wonder how many have had their blood tests affected by biotin supplements?
Thyroid. 2017 Jun 14. doi: 10.1089/thy.2016.0623. [Epub ahead of print]
A single 10mg oral dose of biotin interferes with thyroid function tests.
Biscolla RPM1, Chiamolera MI2, Kanashiro I3, Maciel RMB4, Vieira JGH5.
1 Grupo Fleury, 89577, Endocrinology, Sao Paulo, SP, Brazil ;
2 Grupo Fleury, 89577, Endocrinology, Sao Paulo, SP, Brazil ;
3 Grupo Fleury, 89577, Endocrinology, Sao Paulo, SP, Brazil ;
4 Grupo Fleury, 89577, Endocrinology, Sao Paulo, SP, Brazil ;
5 Grupo Fleury, 89577, Endocrinology, Sao Paulo, SP, Brazil ;
This letter reports a study with a single 10 mg oral dose of biotin in 19 health subjects. The acute use of biotin interferes with measurement of TSH, free T4 and T3, in a fashion similar to a hyperthyroid subject, and the changes are reversible 24 hours after the biotin ingestion.
Edited 12:23 18/06/217:
Just want to make it crystal clear, this biotin issue does not affect all versions of thyroid function tests. It is an issue with the test itself - not any impact on your actual levels.
Edited 19:22 22/06/2017:
Drug Discov Ther. 2016;10(6):338-339. doi: 10.5582/ddt.2016.01074.
Biotin treatment causing erroneous immunoassay results: A word of caution for clinicians.
Department of Medical Genetics, King Faisal Specialist Hospital and Research center.
Biotin or vitamin B7 when ingested in high doses may cause immunoassay interference leading to false potentially misleading results. It is important that clinicians should always interpret laboratory results in the context of patient's clinical state as erroneous results may lead to misdiagnosis and injudicious treatment with adverse patient outcome.
[Indexed for MEDLINE]
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