what fingernails say about disease
Often, spoon nails are a sign of iron deficiency anemia or a liver condition known as hemochromatosis, in which your body absorbs too much iron from the food you eat. Spoon nails can also be associated with heart disease and hypothyroidism.
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, crumble, lack a cuticle and detach from the nail bed in places. Yellow nail syndrome is often a sign of respiratory disease, such as chronic bronchitis. Yellow nail syndrome can also be related to swelling of the hands (lymphedema). In rare cases, yellow nails can indicate a more serious condition such as severe thyroid disease, lung disease, diabetes or psoriasis.
Onychorrhexis is the medical term used to describe longitudinal ridges on the nails that often accompany brittle nails. In contrast to longitudinal ridges, Beau's lines are horizontal or transverse depressions in the nail that may be confused with nail ridging.