Nail - A diagnostic tool

Before surgery women are asked to remove their nail polish because when a patient's lips are covered by an anesthesia mask, it is the nails that the anesthetist will examine to ascertain whether the patient is getting enough oxygen. Pink nail beds indicate enough oxygen in the blood, but pale or blue ones show that the patient is not receiving enough oxygen.

A skilled diagnostician can also read the nails for signs of certain ailments. Pale, upward curving nails may indicate anemia or zinc deficiency. Blue-ginged nails show that blood is not reaching the extremities - possibly a sign of circulatory disease and ridged nails show that the growth was interrupted, possibly by illness.