Fingernails have lots of uses — from scratching in self-defense to painting in self-expression. They are particularly helpful in giving us relief from an itch or helping us out with a lotto ticket. But there is a lesser known use for nails that many people are not aware of: an excellent source of information concerning our health. From discoloration to odd shapes, many changes in your nails' appearance can be an indication of something going on inside your body.

Nails are layers of keratin, a protein also found in our skin and hair. They grow from the area at the base of the nail under your cuticle. As new cells grow, older cells become hard and compacted and are eventually pushed out of your fingertips in the form of your nails. Healthy nails are smooth, free of discoloration, and grooves. Often vertical ridges will develop and become more prominent with age, but these are harmless. Injury can also cause white spots to appear on nails, but these will often grow out. Here are a few conditions visible in your lovely talons:

Lack of Oxygen in Blood

Cyanosis, or the lack of oxygen in blood, can be easily spotted by its tendency to turn an individual’s nails a bluish tint. Red blood cells carry oxygen to the body's tissues and usually have a pink coloring. When the blood loses oxygen, it can turn a dark-bluish red and causes an individual’s skin and nails to take on a blue hue. Cyanosis is often indicative of lung problems and occurs when there are blood clots in the lungs, at high altitudes, in bronchiolitis, CODP, severe pneumonia, and a number of other lung-related conditions.

Nutritional Deficiencies

Koilonychia is a condition that causes the nails to become indented and curve inward like a spoon. It can indicate that either the body has too much iron (haemochromatosis) or too little iron (anemia). Pale, whitish-colored nails are also a common symton of anemia. Individuals suffering from malnutrition may also experience thin, brittle nails. Ridges along the nails can indicate an array of nutritional problems including iron, folic acid, and protein deficiency.

Dry, brittle nails. Photo courtesy of Toshiyuki IMAI CC BY-SA 2.0. Toshiyuki IMAI CC BY-SA 2.0

Skin Issues

According to the UK’s National Health Service, between 10 to 50 percent of people with psoriasis experience pitting or small indentations in their nails. Psoriasis is a lifelong condition that changes the life cycle of skin cells, causing them to build up rapidly on the surface of the skin. Pitting also exists in those with alopecia, a condition that causes chronic hair loss. Psoriasis also causes red or brown little streaks under the nails, loose nails, and thickened overgrown nails.

Thyroid Problems

The thyroid is an important part of the endocrine system and is located at the front of the neck just below your collarbone. Individuals who suffer from either an overactive thyroid or underactive thyroid, often have brittle and crumbly nails. This is because the condition affects the metabolism and can cause individuals to sweat less. This reduction in sweat causes the nails and skin to become dry or flaky.