A perfectly manicured hand is one where the nails are strong and smooth, with no discoloration, jagged cuticles or other signs of abuse. So what about nails that are less than perfect? Since many health problems have an impact on the nails, it's worth listening to what your hands have to say.

Next time you have a client sit down for a manicure, if you notice any of these signs you may want to point them out. According to Dr. Ariel Ostad, a Manhattan Board Certified Dermatologist, nails can say a lot about your client's health. See what he says to watch out for:

Beware of Dangerous UVA Rays at the Nail Salon: Doctors raised the alarm after two women developed tumors on their hands from exposure to ultra-violet lamps used to fix artificial nails. The lamps can also be bought for home use. But experts now fear the high dose of UVA rays-the most dangerous form of ultra-violet light they produce could be damaging skin cells. "Regular users should have their hands and fingers inspected for signs of cancerous growths," says Dr. Ostad. Because the matrix originates under the cuticle, getting a manicure can harm it if the equipment isn't sterilized. And when a drill is inserted under the cuticle to smooth it, the matrix cells can be ground up so badly that they cannot regenerate. Nail sculpture chemicals can also drip down into the matrix, causing damage. "When the matrix cells are damaged, they may never grow properly again, and the nail will always be deformed," says Dr. Ostad.

It's the Pits. When the normally smooth surface of the fingernail has several small dents or pits in it, that can be a signal that something is going on beneath the nail. Most often, the cause of those dents is psoriasis. The inflammatory skin condition-it shows up as red, scaly patches on the skin-can also affect the skin cells in the nails. Instead of growing out smoothly, the surface of the nail takes on a dented appearance. Once the psoriasis is treated and under control, nails will slowly return to normal. Since nails only grow about a millimeter per week, it will take a few months for the old, pitted nail to fully grow out and be replaced with a healthy one.

What Do Spoon-shaped Nails Indicate? A healthy nail has a specific shape-slightly raised in the middle, then curving down a bit at the tip. So when you see a nail with the exact opposite configuration that should be a clue that all is not right. "Dark nails or thin, flat, spoon-shaped nails are a sign of iron deficiency anemia," says Dr. Ostad. As with many health problems, it can take months of iron deficiency before the problem shows up in the nails. And when the anemia is corrected, it will take awhile for normal-shaped nails to re-grow.

Peeling Nails? Why It's Happening. The nail plate is made up of several layers of keratin (a protein). Ideally, those layers are sealed together to form a unified, strong nail. But when nails aren't protected-your hands are in water a lot, or exposed to cold, dry air-those layers tend to delaminate. The result is nails that are likely to peel. Besides being an indication that you need to take better care of your nails-polish can help seal the layers and moisturizing them several times a day will keep the layers supple-peeling nails can mean a diet that's lacking in linoleic acid. The easiest way to up your intake is to increase your use of vegetable oils.

Brittle Nails: By some estimates, about 20 percent of women suffer from a condition called "brittle nail syndrome." While it may sound like just a fancy name for nails that break easily, the causes go deeper than that. Brittle nails are ones that can't hold on to moisture, so the layers of the nail plate dry out and crack. Medically speaking, it's possible for an under-active thyroid to cause both dry skin and brittle nails. Nutritionally, a diet low in iron can cause nails to become thin, brittle and easily broken (eating more green, leafy vegetables, red meat and eggs will help boost your iron intake). Biotin supplements (a B-complex vitamin) have also been shown to improve the condition of brittle nails. The main culprit of brittle nails? Excessive exposure to water.

It's Not Easy Being Yellow: A healthy nail (with healthy skin beneath its bed) has a soft, pinkish hue. When it doesn't, that may be a reason to worry. "When all of the nails turn yellow it can be a sign of lung disease or diabetes," says Dr. Ostad. "Yellow spots on the nails can be an indicator of fungus or psoriasis." Since any of these conditions warrants treatment by a doctor, it's worth seeing a dermatologist if yellow nails persist. Women who frequently wear very dark nail polish for long periods of time (especially without using a protective basecoat underneath it) may also notice a slight yellowing of their nails, but it's no reason to panic. The nails are merely stained from the polish and will return to their normal shade if they are left unpolished for a while.