FERRITIN EXCRETION AND IRON BALANCE IN HUMANS

Under normal circumstances, most of the lumenal iron taken into the in testinal mucosal cell is stored within the cell as ferritin and subseq uently is lost in the faeces when the cell exfoliates at the end of it s lifespan, To evaluate whether faecal iron proteins reflect mucosal c ell iron as well as whole body iron and to examine further the kinetic s of gastrointestinal iron transport, faecal H-rich and L-rich ferriti n were measured in normal subjects and patients with iron deficiency a nd genetic haemochromatosis. In normal and iron-deficient subjects, th e concentration of L-rich but not H-rich faecal ferritin correlated cl osely with body iron status. In genetic haemochromatosis, the faecal L -rich and H-rich ferritin concentrations were lower than expected for their body iron status. The administration of oral iron to normal subj ects led to a rise in L-rich ferritin. Administration of oral or paren teral iron to patients with iron deficiency led to a prompt rise in bo th forms of faecal ferritin, although the relative increase of L-rich ferritin was greater than that of H-rich ferritin with oral iron admin istration. Faecal ferritin correlated closely with iron stores in norm als and patients with iron deficiency but faecal ferritin levels were lower than expected in genetic haemochromatosis, similar to that previ ously noted in the duodenal mucosal cells of these patients.