Koilonychia

Koilonychia is a nail disease that can be a sign of iron-deficiency anemia. Koilonychia means literally "spoon nails." It refers to nails (usually of the hand) which have lost their convexity, becoming flat or even concave in shape. In a sense, koilonychia is the opposite of nail clubbing.

Koilonychia is associated with Plummer-Vinson syndrome.