Iron deficiency anemia is a condition caused by a lack of iron in the body, which reduces the number of red blood cells. Without enough iron, the body cannot produce sufficient hemoglobin in red blood cells to carry oxygen. Common causes include blood loss, an iron-poor diet, inability to absorb iron, and pregnancy. Symptoms include extreme fatigue, weakness, pale skin, and shortness of breath. Diagnosis involves tests of red blood cell count, hemoglobin levels, and iron storage protein levels. Treatment focuses on taking iron supplements with food or vitamin C to aid absorption.