Iron deficiency causes duodenum mucosal hyperplasia in male Wistar rats

Administration of an iron-deficient diet to Wistar rats resulted within 14 days in reduced serum iron concentrations, a microcytic hypochromic anemia, characteristic for impaired hemoglobin synthesis, and an increase of duodenal epithelial cell proliferation. After 5 weeks of iron deficiency, hypochromic microcytic anemia and a clear increase of duodenum weight but no pronounced effects on cell proliferation was observed. Increased duodenum weights corresponded to significant increases in mucosal area, indicating a diffuse, simple mucosal hyperplasia. The sequence of events following iron depletion thus appears to be: (1) reduced serum iron levels, (2) induction of hypochromic microcytic anemia, (3) increased duodenal epithelial cell proliferation, and (4) increased duodenal weight (increased mucosal area). Iron deficiency anemia was rapidly reversible after a 2-week recovery period. However, increased duodenum weights were still noted at that time. Intramuscular iron supplementation in animals fed with iron-deficient diet maintained body iron levels not below normal values, and neither anemia nor increased duodenum cell proliferation were detected after 14 days. A 5-week iron supplementation period resulted in slightly increased serum iron values, and slightly decreased duodenal epithelial cell proliferation. Thus, increased duodenum mucosal hyperplasia was shown to be secondary to depletion of body iron and anemia and reflects an attempt to increase iron absorption to counteract iron deficiency.