What is yellow fingernails?

There are many reasons for yellowing fingernails, such as psoriasis, fungal infections can lead to yellowing nails. It may also be caused by exogenous yellowing caused by exposure to certain chemicals, or eating too many oranges, carrots, etc. will not only lead to yellowing of the skin, but also lead to yellowing nails. It may also be caused by a lack of iron, calcium and other elements in children.