Hashimoto's disease can lead to brittleness of the nails, making them more susceptible to cracking and breaking. Individuals may also notice vertical lines along the length of the nail, a condition known as nail plate furrowing.
Furrows can vary in appearance, presenting as many fine lines or as a single deep line. It is important to note that furrows are not exclusively caused by hypothyroidism; they can also result from other thyroid diseases. Additionally, factors such as aging, iron deficiency, genetic predisposition, psoriasis, and mechanical injuries can contribute to the development of nail furrows.
In cases of hypothyroidism, the outer part of the nail plate may separate from the nail bed. This separation typically starts at the distal (tip) part of the nail and progresses toward the proximal (closer to the hand) area. As a result, air gets trapped between the nail plate and the nail bed. The separated portion of the nail plate may take on a distinct color, often white, but it can also appear brown or yellow. This condition is known as onycholysis and can affect not only those with hypothyroidism but also individuals with hyperthyroidism.
