Most cases of white nails in children are due to trauma, where children develop dotted white nails due to playfulness and a tendency to stumble or pinch their fingers.
If a child develops a full white nail, it may be a congenital full white nail, caused by heredity, or it may be due to other diseases that cause cirrhosis in children.
In children with linear white nails, it may be due to a niacin deficiency.