Intestinal Mucosal Mechanisms Controlling Iron Absorption

Radioautographic studies provide evidence to support a concept of themechanism whereby the small intestine controls absorption of iron. Threedifferent states of the body’s iron stores have been considered in this regard:iron excess, iron deficiency and normal iron repletion. As the columnarepithelial cells of the duodenal villi are formed they incorporate a portion ofintrinsic iron from the body’s iron store, the amount depending upon thebody’s requirement for new iron. It is predicated that with iron excess theiron-receptor mechanism in these cells is saturated with intrinsic iron; thisthen prevents the cell from accepting dietary iron. In the normal state ofiron repletion the receptor mechanism remains partly unsaturated, allowingsmall amounts of dietary iron to enter the cell. Part of this proceeds into thebody to satisfy any metabolic requirement for iron. Part is retained in themucosal epithelial cells to complete the saturation of the iron-receptormechanism. This bound iron is subsequently lost when the epithelial cellsare sloughed at the end of their life cycle. In iron deficiency it is postulatedthat the receptor system is inactive or diminished so that entry of dietary ironinto the body is relatively uninhibited.

Submitted on February 12, 1963 Accepted on April 3, 1963