You might want to check out things Dr. Mercola & many others have to say about potential dangers of soy. It is for sure the last thing you need if you want to perk up your thyroid.
I am hypothyroid and take Armour. If I have a gel cap made with soy the next day I will feel like I didn't take my meds. Soy is a goitrogen and not only that if you are male it is interesting to note that it is estrogenic!
(If one WANTS more estrogen yam creams do the same thing w/o the thyroid harm or any harm that I know of. But then one should take something like ProGest, too, to balance out the extra estrogen no matter what the source.)
Hair loss, especially if it is at the outer ends of the eyebrows, is characteristic of low thyroid. If you have any suspicion there see stopthethyroidmadness.com.