Normal iron absorption determined by means of whole body counting and red cell incorporation of 59Fe.

Gastrointestinal iron absorption has been measured in 27 apparently healthy subjects (8 males and 19 females) by means of whole body counting. Whole body retention 14 days after oral administration of 10 muCi59Fe with a carrier dose of 9.9 mg Fe2+ was used as an expression of absorption. The percentage incorporation of the orally applied 59Fe into the total erythrocyte mass within 14 days (erythrocyte incorporation) was estimated as well. Geometric mean iron absorption was 9.1 +/- 2.2 (S.D.) % in males and 8.3 +/- 2.1% in females; in the entire series it was 8.5 +/- 2.1%. The difference between males and females was not significant. Arithmetic mean red cell utilization of absorbed 59Fe was 92.9 +/- 4.0 (S.E.M.) % in the entire series. The correlation between iron absorption and erythrocyte incorporation was found to be highly significant (r=0.96, p less than 0.001).