Muehrcke Lines of the Fingernails

Muehrcke lines are paired, white, transverse lines that signify an abnormality in the vascular bed of the nail. Muehrcke first described paired, narrow, white, transverse fingernail lines in a series of 65 patients with severe, chronic hypoalbuminemia (Muehrcke, 1956). He believed that the lines were a specific sign of this single biochemical alteration. Others described patients receiving multiple cytostatic agents (Schwartz, 1979). These nail alterations may also represent an example of chemotherapy-induced nail changes.

Transverse white lines of the nails occur with many different etiologies. They have been shown to occur in association with several conditions, including pellagra (Brownson, 1915), Hodgkin disease (Shahani, 1973), renal failure (Hudson, 1966), sickle cell anemia, or nail damage from paraquat (Samman, 1969).

Transverse white bands appearing in the nail plate are often caused by trauma to the more proximal matrix in the area of the proximal nail fold; however, some bands, such as Mees lines and Muehrcke lines, are associated with systemic disease. The systemic disease-associated lines typically span the entire breadth of the nail bed or the nail plate, and they tend to be more homogenous, to have smoother borders, and to occur on several nails at once (Daniel, 1997). Trauma-induced transverse white bands tend to be more linear, they resemble the contour of the proximal nail fold, and they usually do not spread across the entire breadth of the nail plate, whereas systemic disease-associated lines typically have a contour similar to the distal lunula and a rounded distal edge. Usually, a correlation between the onset of the bands and a systemic insult exists; a history of physical trauma to the cuticle area is not likely (Daniel, 1997).

Pathophysiology:The appearance of the paired, narrow, white bands on the fingernails is typically correlated with a serum albumin level below 2.2 g per 100 mL. The lines have been shown to persist with chronic hypoalbuminemia and to disappear when the serum albumin level rises above 2.2 g per 100 mL (Muehrcke, 1956). The exact pathogenesis has not been sufficiently articulated. A localized edematous state in the nail bed may exert pressure on the underlying vasculature, thereby decreasing the normal erythema typically seen through the nail plate (Daniel, 1997).

Muehrcke observed the fingernails of 250 healthy adults, 500 patients with serum albumin levels in the reference range (values <4 g per 100 mL were taken as abnormal), 31 patients with nephrotic syndrome, and another 34 patients with hypoalbuminemia from other causes. The paired, white bands were not found in any healthy subjects or in patients with serum albumin levels of greater than 2.2 g per 100 mL. Of the 31 patients with nephrotic syndrome, 23 (74%) had paired, transverse, white bands. Of the other 34 patients with hypoalbuminemia, 9 had serum albumin levels of less than 2.3 g per 100 mL, 8 of whom developed the white bands. In 1 patient with a serum albumin level of 2.0 g per 100 mL, the bands did not develop; however, her albumin level had decreased from 2.7 g per 100 mL in the previous 2 weeks. The bands were more prominent in patients with albumin levels of less than 1.8 g per 100 mL for at least 4 months (Muehrcke, 1956).