More things your nails say about your health

Clue 5: Rippled, pitted nails

Look for: Tiny indentations or holes in the nail bed called "pits." The nail may also appear to be rippled rather than smooth. (You can also feel these abnormalities by rubbing your finger across the nail, which is normally as smooth as the inside of a seashell.)

What it might mean: Psoriasis. Between 10 and 50 percent of patients with this common skin disease have pitted, hole-pocked nails, according to a 2000 report in Primary Care. So do more than three-fourths of those with psoriatic arthritis, a related disorder that affects the joints as well as the skin. More rarely, Reiter's syndrome and other diseases of connective tissue show this symptom.

Next steps: A doctor can prescribe medications to treat the underlying conditions. The nail bed can often be restored in psoriasis when the treatment starts early.

Clue 6: Brittle nails

Look for: Peeling, splitting, or easily cracking nails. Sometimes vertical ridges mar the surface, too. These telltale wrecked nails are sometimes called "hypothyroidism nails."

What it might mean: Thyroid disease. Hypothyroidism, or underactive thyroid, occurs when the thyroid gland doesn't make enough thyroid hormone. (Typically a patient's hair is also thin and brittle.) Metabolic functions throughout the body are disrupted, including the delivery of moisture to the nails. Pale, dry skin and hair that may fall out are related signs. Hyperthyroid (overactive thyroid) diseases, such as Grave's disease, may also cause brittle nails.

Next steps: Skip the over-the-counter nail strengtheners for persistently brittle nails and get thyroid levels checked; if thyroid disease is the cause, it's important to treat the root problem.

Clue 7: Nails that seem to be "lifting off"

Look for: The nail itself separating from the nail bed, which is the layer of skin directly under the nail. This effect, known medically as onycholysis, often begins at the fourth or fifth fingernail. Toes can also be affected. It's also called "Plummer's nails" (after the physician Stanley Plummer, who described them in 1918) or "dirty nails," because debris can accumulate and be seen.

What it might mean: Thyroid disease. Hyperthyroidism, in which too much thyroid hormone is produced, can cause excessive nail growth and lead to this deformation. Plummer's nails tend to occur in younger patients rather than older ones.

Next steps: Other hyperthyroidism symptoms to be aware of include fatigue, difficulty concentrating, increased appetite, weight loss, sweating, hair loss, itching, and protruding eyes.

Clue 8: Depressions running across the nail horizontally

Look for: White ridges running across the width of the nail bed. These so-called "Beau's lines" (after the French physician who described them) can occur in all or just one nail; if in all nails, they're at about the same place on all of them. They're actual ridges in the nail plate itself.

What it might mean: Diabetes, psoriasis, Raynaud's disease -- or just a trauma to the nail. Beta-blockers and drugs used in chemotherapy can also produce Beau's lines. Some people develop them simply as a result of aging.

Next steps: Consider this effect just one piece of a puzzle. Nails grow about 1 mm every six to ten days, so doctors use this measurement to estimate when the problem might have begun.

Clue 9: White bands running across the nail horizontally

Look for: The white-colored bands, known as "Mees' lines," run transverse (parallel to the white tips of the nails). They may affect one nail or several, occurring at about the same spot on each nail. Because the problem is in the nail itself, the line moves forward as the nail ages -- allowing doctors to date the time the problem began.

What it might mean: Arsenic poisoning! Hair and tissue samples should be tested to verify. It's pretty rare these days, Anderson says, but worth knowing about.

Next steps: Make an appointment to see a doctor -- and avoid eating anything you don't prepare yourself!