Thyroid numbers + Biotin products

I've had my thyroid function removed with radioactive iodine over 25 years ago, and I'm on 100mcg of levothyroxine now. I have never heard of hair products affecting thyroid levels. My doctor and I had a discussion over levothyroxine recently, my pcp had good advice, take your levothyroxine with water, like the pharmacy sticker on my bottle says. And your habits should be fine if your TSH tests come back within the reference range. Request a TSH test if you're unsure, and always know your levels and your spot on the reference range. If I'm feeling a bit off, I always request a TSH test first, from my doctor, it (TSH) can change.

@jaymie78 you will notice that I have moved your post into a the Diabetes/Endocrine Group (as well as Women's Heath still) and updated your title to allow you to better connect with other members with thyroid experiences.

I found the following article that you may find useful. This is in reference to actual biotin supplements, rather than haircare products, however. I am unsure of the effect of topical biotin use and how that may interact. That would be worth talking to your doctor about in greater detail.
https://www.thyroid.org/patient-thyroid-information/ct-for-patients/december-2018/vol-11-issue-12-p-3-4/#:~:text=Most%20commonly%2C%20biotin%20use%20can,hormone%20dose%20is%20too%20high.
Have you had changes in your health and your thyroid numbers?

more on my conversation, is that the doctor told me that thryoid replacement is known to bind to certain substances. His quick example was calcium. don't take a levothyroxine with milk, as it binds to the calcium and is less effective. Biotin perhaps is another substance that thyroid replacement binds to inside your body. We came to the conclusion that my thyroid level was fine, and my habits were fine, as I take my levothyroxine with tea, and always have, and my thryoid tsh levels are within reference range. This is my point. I've never heard of hair shampoo impacting my tsh levels.