I have been low thyroid on every test since I was in my early 30's. It is only when I developed diabetes, hypertension, and a few other fun maladies in menopause that I started to seriously use thryroid replacement---Armour, because it's the real stuff.<G> Besides being overweight, I never would have known that I was hypothyroid. Now you mention brittle nails. This has started in the past few months, but up until then, I had the ability to grow "talons!" I used to have to cut them back; simple filing wouldn't do it. When I did a serious manicure, people thought I had falsies.<G> I may have been low T3/T4, but I never knew it other than from the blood test and perhaps the weight, but I think that was/is appetite more than anything. I'm not cold, quite the opposite. Anything I should know?