White nails may be caused by a change in the colour of the nail bed resulting in a white nail, or the nail plate itself may lose its transparency and appear dotted, linear, partially or fully white.
It may be caused by congenital heredity, by trauma or exposure to chemicals, and can also be seen in patients with certain skin conditions such as nail fungus, psoriasis or systemic diseases such as cirrhosis of the liver or nephrotic syndrome.