[Iron metabolism and iron-refractory iron deficiency anemia]

Hepcidin is a key molecule that regulates iron metabolism in the body. Iron refractory iron deficiency anemia (IRIDA) is a genetic disorder caused by a defect in the TMPRSS6 gene encoding matriptase-2, a transmembrane serine protease that physiologically inhibits hepcidin production. In patients with IRIDA, the iron uptake in the intestine is remarkably reduced, and iron deficiency anemia (IDA) develops. However, in contrast to the ordinary IDA, high hepcidin levels in IRIDA keep the serum ferritin levels normal or sometimes high. Due to the malabsorption of iron in the intestine, IRIDA is refractory to oral iron supplementation, but partially responds to parenteral iron administration. A high hepcidin level gives IRIDA a lot of similarities with anemia of chronic disease, and a differential diagnosis between the two disorders needs careful inspection. Diagnosis of IRIDA needs genetic testing that is hardly available in most facilities, and therefore its clinical features are not fully understood.