Paleness
Paleness of the skin, inner lower eyelids, fingernails, and toenails, inside of the mouth, gums, and other areas paleness can be observed are often indicative of a deficiency of iron in the blood.
Hemoglobin, which depends on iron for its production, is what gives human blood its red color. When there is a shortage of iron in the body, the red blood cells reduce the production of this compound. This results in the paleness observed in iron-deficient people.
Pulling down the lower eyelid to observe the inside is the easiest method to check for iron deficiency. The inner lower eyelids of a person who has sufficient iron in their body are usually red, provided the iron present in their body is being absorbed properly. When the iron levels are low, this area appears near white or a very pale red.