Spoon-shaped nails, or koilonychia, indicates an iron deficiency, which can cause iron-deficient anemia. Iron-deficient anemia can cause the patient to tire easily. Clubbing of the fingers, which results in fingernails that are overly convex, points to chronic lung disease such as those caused by smoking. A zinc deficiency can cause a rash but not changes to the fingernails. Although chronic alcohol use can lead to iron deficiency and koilonychia, there are other causes of iron deficiency and asking about the symptoms of iron deficiency is a better option for the nurse.