Muehrcke’s nails is a type of leukonychia striata characterized by horizontal white lines on a nail that run parallel to the lunula (the crescent shaped whitish area that appears at the bed or proximal area of a fingernail or toenail). Because they are part of the vascular nail bed that exists underneath the nail plate, they do not move or “grow out” when the nail grows. Additionally, the transverse lines tend to disappear when pressure is applied to the nail, at least temporarily.
The nail abnormality was first described by American physician Robert C. Muehrcke in a 1956 issue of British Medical Journal after he noticed transverse, white lines on the nails of patients with chronic hypoalbuminemia (a medical condition in which blood levels of the protein albumin are abnormally low). Albumin is made in the liver, and as sites like MedScape and WebMD point out, it helps distribute hormones and vitamins throughout the human body, as well as helps keep fluid from leaking out of the blood vessels.
In addition to being linked to hypoalbuminemia, Muekrcke lines have also been seen in patients who have:
When Muehrcke lines are associated with a serum albumin deficiency, albumin infusions can help the lines disappear. Otherwise, treatment of the specific health problem that caused the lines will eventually eradicate the condition.