Nail clubbing, nail pitting and Beau's lines are some conditions that cause bumps on fingernails, explains Mayo Clinic. Nail clubbing is when the nail convexes to create a single, large bump in the center. The condition can be caused by low blood-oxygen levels and could be a sign of cardiovascular disease, lung disease, inflammatory bowel disease, liver disease or AIDS. Nail pitting is small depressions in the nails, which are a possible sign of psoriasis or connective tissue disorders.
Beau's lines are indicated by indentations across the nail, which can be caused by peripheral vascular disease or uncontrolled diabetes, states Mayo Clinic. Other causes of Beau's lines are zinc deficiency or an illness that causes high fever.
Color changes in the nails can also point to an underlying condition, according to WebMD. Pale nails are a possible sign of anemia, liver disease, congestive heart failure or malnutrition. White nails with dark sides can point to hepatitis or other liver problems. Yellow nails are often a sign of a nail fungus, but can also be a sign of lung disease, diabetes or severe thyroid disease. Changes in nail texture or color does not always signify an underlying condition, but worrisome changes should be brought to the attention of a dermatologist.