Iron Absorption in Patients with Chronic Uraemia

The purpose of this study was to examine the accuracy of iron absorption calculated from the incorporation of radioiron into red cells (RCI), compared to measurement by the whole body counting technique (WBR). RCI of orally administered 59Fe, and absorption of 59Fe assessed by WBR were measured simultaneously in 53 chronic uraemic patients (16 nondialysed, 18 peritoneal dialysed, 19 haemodialysed), 14 renal transplanted patients with normal renal function, and 27 healthy subjects. In the majority of subjects RCI values were lower than corresponding WBR values, with mean red cell 59Fe utilization values (RCI/WBR ratio X 100) in the various groups from 78% to 93%. All groups demonstrated significant correlations between RCI and WBR with r values from 0.963 to 0.996 (P less than 0.001). RCI was higher in patients with reduced marrow iron stores than in patients with adequate iron stores (P less than 0.001), and was correlated both to plasma transferrin (r = 0.59, P less than 0.001) and serum ferritin (r = -0.88, P less than 0.001). In all groups there was good accuracy of calculated iron absorption (from RCI) compared to 'true' iron absorption (by WBR) with r values from 0.963 to 0.995 (P less than 0.001). Iron absorption measurement based on red cell incorporation appears to be a practical and accurate alternative to whole body counting, both in healthy subjects and in patients with chronic uraemia.