Liz1967
i have had the same thing on my left big toenail since Graves began, even when on methimazole for the first 6 months so pretty sure not an effect of levothyroxine. I cannot really tie it to either hyper or hypo. My fingernails have always been brittle so that didnt change. I will say hair growth is negatively affected if my TSH wanders above 2. As ridiculous as it sounds, I cut the nail as short as possible, be sure there is enough room in the toe of my shoes that that nail does not catch and get pulled up by the shoe, and clean it out after bathing or soaking with an orange stick and put Vicks vaporub under the nail. This is totally unproven but somehow I manage to get the nail looking almost normal if I remember to do everything. I also try to smooth it out by a course emery board across the middle where it forms a hump. I wear toeless sandals all summer too. It has to be a fungal thing, but how it relates to thyroid levels is a mystery. The dry skin affects nail cuticle and putting vaseline just on cuticle helps mine a bit.