High cholesterol can result in unusually thick nails or brittle ones that break easily. In rare cases, dark lines, known as splinter hemorrhages, may form under the finger or toenails. The NHS ...

Splinter hemorrhage (nail trauma ... Most of the time, thin, vertical black lines under your nails are no cause for concern.

Psoriasis is a common, chronic inflammatory dermatosis, and patients with psoriasis often develop nail involvement. It is ...