What is the most common cause of iron deficiency anemia in adults?

• A. Chronic blood loss
• B. Dietary iron deficiency
• C. Inadequate erythropoietin production
• D. Genetic iron metabolism disorder

Answer: (A)

Chronic blood loss is the most common cause of iron deficiency anemia in adults because iron is lost with the blood faster than it can be replenished through diet and absorption. Over time, repeated losses—often from the gastrointestinal tract (ulcers, gastritis, polyps, hemorrhoids, or even colon cancer)—deplete iron stores. As iron stores (ferritin) drop, serum iron falls and transferrin saturation decreases, while total iron-binding capacity rises. With insufficient iron, hemoglobin synthesis suffers, producing microcytic, hypochromic red blood cells.

Dietary iron deficiency is much less common in adults in developed settings, since iron intake often meets needs unless there is very poor nutrition or absorption issues. Inadequate erythropoietin production causes a different pattern of anemia (often normocytic) seen with kidney disease or other conditions that blunt red cell production, not primarily iron deficiency. Genetic iron metabolism disorders typically cause iron overload rather than deficiency.