WATCH YOUR FINGERNAILS

Have you ever wondered what the ridges on your nails can reveal about your health?

- Miranda McMinn

O ur fingernails are our version of animals' claws, made from the same substancekeratin as our hair, and the hooves and horns of vertebrates.

They grow twice as fast as our toenails, faster in men than women. They don't hurt when you cut them because, apart from the small moon, the part we can see is dead. So far, so fascinating. But what if you look down and see that you have developed ridges where there used to be none? Should you worry? What are the different kinds of fingernail ridges? There are two types:

Longitudinal or vertical ridges which run vertically up and down in the direction of your fingernail.

Horizontal ridges which go across from one side of the finger to the other.

Dr Dhruvkumar Laheru is a consultant dermatologist and the nails lead for the British Hair and Nail Society. He explains, "Usually horizontal ridges are a sign that some form of interruption or change has happened in the growth of the fingernail." But he adds this is not necessarily a diagnostic tool for an existing condition, as it is usually something that has happened in the past. "Ridges are a bit like rings in a tree, they're a marker of things that happened a while ago, a bit like a glacier-it flows forward like a river, but is incredibly slow."

For a nail to grow from the beginning, forming under the cuticle in the nail matrix, to the end where you clip it off, takes around a year for a fingernail and two years for a toenail in an adult.

"So for things that happened to show up as a horizontal ridge would have happened a while ago."

(And it's not true that fingernails continue to grow after you die-the effect is caused by skin dehydrating and tightening, making the hair and nails appear to grow.)

The most common cause of horizontal ridges