APPLICATION OF MAGNETIC-SECTOR THERMAL IONIZATION MASS-SPECTROMETRY TO STUDIES OF ERYTHROCYTE IRON INCORPORATION IN SMALL CHILDREN

The optimal evaluation of iron metabolism requires the administration of two isotopes of iron, However, high-precision measurement of isotop ic ratios from blood samples obtained after administration of two stab le isotopes of iron to human subjects has not previously been reported , Using a cation-exchange system to isolate iron from blood samples, w e found that high-precision (<0.2%) measurements of Fe-58/Fe-56 and Fe -57/Fe-56 could be performed using magnetic sector thermal ionization mass spectrometry. Clinical studies in four 1-year-old infants showed that this technique could be used to demonstrate a lower rate of iron absorption in small children given an iron supplement (Fe-57) with mil k compared to those given iron (Fe-58 and ferrous sulfate) with ascorb ic acid, This technique will enable the evaluation of iron metabolism in populations in whom the use of radioactive iron tracers is not appr opriate.