Did you know that biotin, the supplement people use to strengthen their nails and hair, interferes with a number of different immunoassays? 

(First of all, do you know what an immunoassay is, LOL? It’s just another name for a blood test.)

I just found this out the hard way. I knew that biotin interfered with the thyroid hormones.  I did not know that biotin interferes with a number of other hormones as well. 

In retrospect, this makes perfect sense as these hormones have been slightly off for me since I began supplementing with biotin to improve my hair and nails. The good news is my hair and nails have never been better 🙂 the bad news is I think some of my lab results have been skewed a bit. 

Bottomline? I have to repeat the blood work without the biotin. Good news? This discovery could be important information for those who get regular blood work every year and who worry about thinning hair and brittle nails.

I do not think this information is well known or properly disseminated.  I shared the information that biotin interferes with thyroid blood work with my physician about six months ago.  

Unfortunately, that was all I was aware of at that point and that is as a result of having written a book about the thyroid. It wasn’t until I began work on this article that I realized it also interferes with a number of other tests. 

Let\’s cut to the chase. Here are the other tests that can be impacted by supplementing with biotin: 

• Troponin – a test used to help diagnose heart attacks

• Thyroid hormone tests, such as thyroid-stimulating hormone TSH, thyroxine (T4), and triiodothyronine (T3) tests

• Other hormones, such as parathyroid hormone(PTH), cortisol, follicle-stimulating hormone (FSH), and luteinizing hormone (Lh)

• Biggest surprise of all Vitamin D

So what can you do?

1. Know that some laboratory platforms use methods that prevent biotin from interfering, so ask your phlebotomist. 

2. Or failing that, known tests that are free from biotin interference can sometimes be used for retesting samples from patients in whom biotin interference is suspected without having to draw another sample.

3. Or as a last resort know that re-testing may be done at a later time, after you have refrained from taking biotin.  According to most of the research, waiting a week should do it, but to play it safe I plan on waiting two weeks before going back to retest.

The reason this is all so important is that thyroid diseases, such as Hashimoto’s, are much more prevalent in women than men and tend to occur in middle age. Hair loss can be caused by thyroid disease. Many women experiencing hair loss supplement with biotin, so their test results are more at risk.  

While we’re on the topic of biotin and hair loss, did you know that it does no good to supplement just with biotin? If you want hair and nails to strengthen you must combine biotin with B12. Biotin alone does not work and actually can make the problem worse whereas biotin combined with B12 is a winner!

So there you have it! Great hair and nails and accurate diagnostic testing. Let us know if this helps.