Absorption of inorganic iron- (59Fe2+) in relation to iron stores in pancreatic exocrine insufficiency due to cystic fibrosis.

The absorption of 59Fe from a diagnostic 0.56 mg 59Fe2+ dose was measured by 4pi-geometry whole body counting and related to the amount of stainable diffuse cytoplasmatic non heme storage iron in the bone marrow macrophages of children with cystic fibrosis. When the storage iron was within the normal range (+/2+) children with cystic fibrosis absorbed 10-38% (Xa+/-S.D.=21+/-9.3) of the oral 59Fe2+ dose which is identical with the 59Fe-absorption in normal children with normal iron stores (9-45:23+/-8.7%). Depleted iron stores caused an increase of 59Fe-absorption to 43-95% (Xa+/-S.D.=62+/-19) in children with cystic fibrosis and to 45-100% (Xa+/-S.D.=73+/-18) in control children. The interruption or continuation of pancreatin maintenance therapy and the simultaneous administration of 1-1.5 g pancreatin did not influence 59Fe2+ absorption in cystic fibrosis. There is no evidence for a pancreatic factor required for or inhibiting inorganic and food iron absorption in human beings. Iron absorption is controlled also in cystic fibrosis chiefly by the amounts of available storage iron. It is therefore not justified to apprehend the development of hemosiderosis in children with cystic fibrosis who are not or not sufficiently treated with pancreatin.