Serum iron increase as a measure of iron absorption - studies on the correlation with total absorption

The correlation between the magnitude of the increase of serum iron after an oral dose of iron and the total absorption of iron was studied in 51 healthy subjects and 10 patients with iron deficiency anaemia. 59Fe-labelled solutions of ferrous sulphate (25-100 mg iron) were administered to the fasting subjects. The serum iron concentration was followed for 4-6 hours and the absorption was measured in a whole-body counter. Good correlation was found between the maximal increase of serum iron and the total amount of iron absorbed after a dose of iron given as a solution. The serum iron method may be used for comparisons of the absorbability of different doses of iron by performing cross-over studies in groups of subjects. However, it was found that in an individual subject the serum iron method could not be used to determine the amount of iron absorbed from an oral dose of iron.