Hello – I’m not familiar with the thyroid testing issue. The National Institutes of Health is always a good source for supplement info, and this is what they had to say about biotin:
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http://www.nlm.nih.gov/medlineplus/druginfo/natural/313.html
You might check the references on the two articles you mentioned to see if that sheds any light as to which is the more credible source.
Take care!