Correlation of postabsorptive serum iron increase and erythrocyte-59Fe-incorporation with the whole body retention of absorbed59Fe

Abstract

Following the oral application of 100 mg⁵⁹Fe-equivalents in different ferrous iron preparations the whole body retention (R) and erythrocyte incorporation (EI) of absorbed⁵⁹Fe as well as the postabsorptive serum increase SII after 3 h were estimated by intraindividual and simultaneous comparison in healthy subjects with normal and depleted iron stores. The regression equationR=(0.0±0.4)+(1.16±0.04)×EI and a Spearman rank correlation coefficientr=0.93 were found to describe the correlation between whole body-⁵⁹Fe-retentionR (mg Fe) and erythrocyte-⁵⁹Fe-incorporation EI (mg Fe) after 2 weeks. The correlation between the postabsorptive serum iron increase SII (µmol/l) after 3 h and the whole body-⁵⁹Fe-retentionR after 2 weeks is characterized by the regression equationR=(0.0±0.8)+(0.36±0.03)×SII and a correlation coefficientr=0.88. Whole body counting of absorbed⁵⁹Fe represents the most sensitive, reliable and only quantitative method for measuring iron absorption or bioavailability in man. If however this method is not available postabsorptive serum increase and it's conversion into iron absorption using the described regression equation is a useful substitute for the at least semiquamtitative estimation of iron bioavailability from oral iron preparations.