Establishment of a simple test for iron absorption from the gastrointestinal tract

Recent studies on iron metabolism have begun to reveal the molecular mechanisms underlying iron absorption, which is dramatically affected in several disorders. In the clinical setting, the ability to determine the status of iron absorption would aid in the diagnosis of pathological conditions. Efforts to develop an oral iron absorption test (OIAT) date back to at least 60 years. However, previous procedures were associated with a number of problems, such as radiation exposure and low reproducibility. In an attempt to resolve these issues, we employed sodium ferrous citrate (SFC), by which the influence of various nutrients and drugs on iron absorption was markedly reduced. We found that OIAT using SFC was simple to perform in both hospitalized patients and outpatients. The increment of serum iron and % transferrin saturation at 120 min after SFC administration was useful in distinguishing iron absorption between healthy volunteers, patients with iron-deficiency anemia, and patients with anemia secondary to chronic disorders, which are respectively characterized by normal, enhanced, and reduced iron absorption. Thus, the SFC-based OIAT may represent a viable screening test for the evaluation of gastrointestinal iron absorption.