What is the primary cause of microcytic anemia?

Microcytic anemia is characterized by the presence of smaller than normal red blood cells, a condition primarily caused by iron deficiency. Iron is an essential component of hemoglobin, the protein in red blood cells that carries oxygen. When the body does not have enough iron, it cannot produce sufficient hemoglobin, leading to the formation of microcytic, hypochromic red blood cells. This results in decreased oxygen delivery to tissues and can manifest as fatigue and weakness in patients.

While folate deficiency and vitamin B12 deficiency can lead to anemia, they typically cause macrocytic (larger than normal) red blood cells rather than microcytic. Chronic disease can also cause anemia but is more commonly associated with normocytic anemia. Iron deficiency remains the hallmark cause of microcytic anemia, making it the correct answer.