I totally understand the hair loss. I was diagnosed with Graves Jan 07. Had Rai 8/07. Went hypo and started Levoxyl in November 07 All was well with my hair until February 08. I started losing a ton in the shower. My hands would be covered after using conditioner. I lost a good size ball of hair every day. I wasn't sure if it was from the levoxyl or if it was after effect of being severely hypo (my TSH went to 111) and my body trying to recover. In any case, I am glad to report that I consider my hair loss normal now. I would say things started to improve in May and by June it was much better. I would say I had a good 3-4 months of hair loss.
I was the same as you. I was taking Evening primrose oil and calcium and Biotin. I also read that low ferratin could be the problem. My internist checked my ferratin and it was 14. Low end of normal is 10. She said that could be contributing factor but no one could say for sure what the cause was. I started taking iron. Ferratin takes awhile to improve. I had it checked at my last draw and it is only at 26 now. I was told it had to be over 50 for improvement with hair. I am not there yet and my hair is much better. Internist told me that as long as I am still getting regular periods I could not overload on iron so there was no concern in taking it - as long as my body tolerated it, meaning it doesn't cause constipation, which is a side effect of iron.
to sum it up I can't honestly say why my hair improved. I stopped taking the biotin and primrose oil. I still take the iron. My TSH is now stabilized so it was out of whack from 11/07-8/08. It took a long time but it was way out of range at 111. My Levoxyl dose is now 175mcg. (I started at 100mcg).
When I was going through it I just wanted to hear someone say that it stopped for them. I can tell you that the hair loss finally stopped for me after at most 4 months. I even tried a shampoo called Nioxin, but I don' t think that had any effect at all. My only suggestion would be to get ferratin (which is iron stores) checked.
Good luck to you. I know its hard to live with. I dreaded taking showers every day because I didn't want to face the problem. Hang in there and I truly hope it stops soon for you.
Take care!
It may take 2-3 months once TSH stable (0.5-2.5) on the right dose of levoxyl.