Influence of infection/inflammation, thalassemia and nutritional status on iron absorption.

Iron balance in human beings is maintained by the control of absorption. Recent observations have demonstrated that a peptide hormone, hepcidin, is the principal regulator of iron homeostasis. It is produced in the liver in response to increasing iron stores. It is also induced by interleukin-6 (IL-6) in infectious and inflammatory diseases. Hepcidin restricts both iron absorption and iron release from stores. Disorders that affect the duodenum or stomach directly, particularly gluten enteropathy and H. pylori infections, also impair iron absorption by damaging enterocytes or reducing gastric acid output. Hepcidin secretion is suppressed by accelerated erythropoiesis even when iron stores are increased. This appears to account for the contribution that excessive absorption makes to the iron overload seen in patients with iron-loading anemias such as thalassemia major. There is some evidence suggesting that two nutritional deficiency disorders (deficiencies of vitamin A and riboflavin) lead to impaired iron absorption or utilization, but further research is needed to reconcile conflicting experimental observations.