Very pale nails can sometimes be a sign of serious illness, such as:
Congestive heart failure
If the nails are mostly white with darker rims, this can indicate liver problems, such as hepatitis. In this image, you can see the fingers are also jaundiced, another sign of liver trouble.
One of the most common causes of yellow nails is a fungal infection. As the infection worsens, the nail bed may retract, and nails may thicken and crumble. In rare cases, yellow nails can indicate a more serious condition such as severe thyroid disease, lung disease, diabetes or psoriasis.
Nails with a bluish tint can mean the body isn't getting enough oxygen. This could indicate an infection in the lungs, such as pneumonia. Some heart problems can be associated with bluish nails
If the nail surface is rippled or pitted, this may be an early sign of psoriasis or inflammatory arthritis. Discoloration of the nail is common; the skin under the nail can seem reddish-brown. Psoriasis is a skin condition that starts in the nails 10% of the time.
Cracked or Split Nails
Dry, brittle nails that frequently crack or split have been linked to thyroid disease. Cracking or splitting combined with a yellowish hue is more likely due to a fungal infection.
Puffy Nail Fold
If the skin around the nail appears red and puffy, this is known as inflammation of the nail fold. It may be the result of lupus or another connective tissue disorder. Infection can also cause redness and inflammation of the nail fold
Dark Lines Beneath the Nail
Dark lines beneath the nail should be investigated as soon as possible. They are sometimes caused by melanoma, the most dangerous type of skin cancer.
Biting your nails may be nothing more than an old habit, but in some cases it's a sign of persistent anxiety that could benefit from treatment. Nail biting or picking has also been linked to obsessive-compulsive disorder. If you can't stop, it's worth discussing with your doctor.
Nails Are Only Part of the Puzzle
Though nail changes accompany many conditions, these changes are rarely the first sign. And many nail abnormalities are harmless -- not everyone with white nails has hepatitis. If you're concerned about the appearance of your nails, see a dermatologist.