Your toenails and fingernails protect the tissues of your toes and fingers. They are made up of layers of a hardened protein called keratin, which is also in your hair and skin. Your nails' health can be a clue to your overall health. Healthy nails are usually smooth and consistent in color. Specific types of nail discoloration and changes in growth rate can signal various lung, heart, kidney and liver diseases, as well as diabetes and anemia. White spots and vertical ridges are harmless. Nail problems that sometimes require treatment include bacterial and fungal infections, ingrown nails, tumors and warts. Keeping nails clean, dry and trimmed can help you avoid some problems. Do not remove the cuticle, which can cause infection.