Duodenal ferritin content and structure: relationship with body iron stores in man.

The relationship between serum ferritin and duodenal ferritin was examined in normal subjects and in patients with iron deficiency, secondary iron overload, or idiopathic hemochromatosis (IHC). A positive correlation between serum ferritin and duodenal ferritin concentrations was found in all groups. In the iron-overload conditions, duodenal ferritin concentration was lower at all levels of serum ferritin in comparison with normal and iron-deficient subjects. Patients with secondary iron overload did not differ from those with IHC, which indicates that any decrease in duodenal ferritin concentration was secondary to the excess body iron stores. Purified duodenal ferritin from normal subjects and patients with iron-overload conditions showed the same two distinct isoferritins by isoelectric focusing. After the oral administration of iron, two additional isoferritins were detected. These resembled the major isoferritins of liver.