**8. Conclusion**

Iron deficiency anemia is the leading cause of microcytic anemia when both the anemia and the microcytosis are severe. Regardless of the age of the patient, gastrointestinal disorders are the most frequent causes, and most of these are due to chronic gastrointestinal bleeding. The frequency of the specific causes of the bleeding varies with age. In most cases of severe microcytic anemia in children, as in adults, referral to a gastroenterologist is appropriate or required.
