Nail abnormalities are problems with the color, shape, texture, or thickness of the fingernails or toenails.

Just like the skin, the fingernails tell a lot about your health.

• Beau's lines are depressions across the fingernail. These lines can occur after illness, injury to the nail, and when you are malnourished.
• Brittle nails are often a normal result of aging. However, they also may be due to certain diseases and conditions.
• Koilonychia is an abnormal shape of the fingernail. The nail has raised ridges and is thin and curved inward. This disorder is associated with iron deficiency anemia.
• Leukonychia is white streaks or spots on the nails.
• Pitting is the presence of small depressions on the nail surface. Sometimes the nail is also crumbling. The nail can become loose and sometimes falls off.
• Ridges are tiny, raised lines that develop across or up and down the nail.

Injury:

• Crushing the base of the nail or the nail bed may cause a permanent deformity.
• Chronic picking or rubbing of the skin behind the nail can cause a washboard nail.
• Long-term exposure to moisture or nail polish can cause nails to peel and become brittle.

Infection:

• Fungus or yeast cause changes in the color, texture, and shape of the nails.
• Bacterial infection may cause a change in nail color or painful areas of infection under the nail or in the surrounding skin. Severe infections may cause nail loss.
• Viral warts may cause a change in the shape of the nail or ingrown skin under the nail.
• Certain infections (especially of the heart valve) may cause red streaks in the nail bed ( splinter hemorrhages).

Diseases:

• Disorders that affect the amount of oxygen in the blood (such as abnormal heart anatomy and lung diseases including cancer or infection) may cause clubbing.
• Kidney disease can cause a build-up of nitrogen waste products in the blood, which can damage nails.
• Liver disease can damage nails.
• Thyroid diseases such as hyperthyroidism or hypothyroidism may cause brittle nails or splitting of the nail bed from the nail plate (onycholysis).
• Severe illness or surgery may cause horizontal depressions in the nails (Beau's lines).
• Psoriasis may cause pitting, splitting of the nail plate from the nail bed, and chronic destruction of the nail plate (nail dystrophy).
• Other conditions that can affect the appearance of the nails include systemic amyloidosis, malnutrition, vitamin deficiency, and lichen planus.

Poisons:

• Arsenic poisoning may cause white lines and horizontal ridges.
• Silver intake can cause a blue nail.