Unless you're a manicure junkie, you may not give your nails much thought, beyond the occasional clip-and-file. They click across a keyboard, scratch an itchy back, get trimmed short or worn long and adorned. At their root, though, nails serve a few purposes: to protect and support the fingers and toes, to help us pick up and grip objects, and to assist in sensing fine touch. Our nails can also be like little windows to our health, revealing underlying conditions or temporary traumas and infections.

Healthy nails are appealing to the eye. Changes to the surface or shape of your nail can mean different things. Some changes are harmless, while others indicate something more serious:

  • Brittleness: The biggest reason why nails split, peel, and break easily is too little or too much moisture. Soft, brittle nails may get too much moisture, whereas dry, brittle nails don't get enough moisture, like during the low-humidity months of winter.
  • Pits, ridges and lines: A dented, pitted surface can indicate a problem like the skin condition psoriasis or a fungal infection. Vertical ridges across the nail surface are common as we age, but deep, horizontal grooves (known as Beau's lines) may develop, usually due to trauma or severe illness that interrupts the nail growth cycle. The lines will eventually disappear as the nail grows.
  • Spooned tips: Someone with an iron deficiency may have nails shaped more like spoons – concave and scooped up at the tips.

Nails in the pink of health will have an even, consistent colour and smooth surface. Nails may change colour when you take certain medications, but like changes to the surface, shifts in nail colour can point to potential problems:

  • White: Most people will have white spots and marks on their nails at one time or another. Not to worry: White spots are usually just signs of minor trauma or injury to the nail. If there are many spots and you have no recollection of injuring the nails, check with a dermatologist, since this may suggest infection. White can occasionally be a sign of something much more serious: Horizontal white lines can appear in severe arsenic poisoning, fully white nails are linked to cirrhosis of the liver, and nails that are half-white and half-pink may indicate kidney failure.
  • Yellow: Notice your nails looking a bit yellow? Have you recently painted your nails with dark nail polish? Ingredients in many nail polishes can temporarily stain the nails yellow. If this is the case, simply stop using the polish and the discoloured portion of your nail should soon grow out and disappear. Otherwise, yellow nails can be blamed on aging, fungal infection, lung disease, build-up of lymphatic fluid in tissues, psoriasis, or diabetes.
  • Brown or black: Slam your fingertips in a drawer hard enough, and you'll likely see a bruise form beneath the nail. Hematomas, those brown or black spots that pop up after an injury, are nothing to worry about. As your nail grows out, the hematoma will grow away with it. On the other hand, if you notice that a dark spot does not grow out with the nail, this could be a tumour beneath the nail. The nails of dark-skinned people may bear brown-black lines extending from the base of the nail to the tip. If the same things appear in someone with lighter skin, they should get it checked out by a doctor - it can be caused by moles or, possibly, skin cancer.

Amy Toffelmire