A NEW METHOD TO MEASURE IRON-ABSORPTION FROM THE ENRICHMENT OF FE-57 AND FE-58 IN YOUNG ERYTHROID-CELLS

Iron absorption can be measured by the incorporation of stable iron is otopes into erythrocytes, 14 days after isotope administration. The di sadvantage of this method is the high dose of isotopes needed to obtai n a sufficient enrichment. Therefore, in this study cell fractions ric h in young erythroid cells were prepared by using a density separation method. From 10 women blood was taken 4, 5, and 7 days after oral and intravenous administration of Fe-57 and Fe-58. In these cell fraction s and in whole blood taken 14 days after isotope administration, isoto pe enrichment was measured and absorption calculated. Absorption calcu lated from the isotope enrichment in the reticulocyte-rich cell fracti ons (12.2 +/- SEM 3.7%) was not significantly different from absorptio n based on whole-blood values (13.0 +/- 3.3%). Because a threefold hig her isotope enrichment was found in the cell fractions, the required d ose of stable isotopes can be reduced to one-third of the dose used in the traditional method without loss of sensitivity.