What does it mean when you have lines on your fingernails?

White lines that appear under the fingernail are the result of injury. However, lines, which are indentations that run across the fingernails, are called Beau's lines. Uncontrolled diabetes, peripheral vascular disease, illnesses associated with a high fever, such as scarlet fever, measles, mumps and pneumonia, and a zinc deficiency are conditions associated with Beau's lines.

Here is the link to a slide show presentation of what Beau's  lines look like. This link is to the Mayo Clinic website.

http://www.mayoclinic.com/health/nails/WO00055&slide=6

I hope that I have answered your question.

Maryann