Iron Absorption by Humans and Swine from Fe(III)-EDTA. Further Studies

Abstract

Studies on iron absorption from Na⁵⁹Fe-EDTA in humans have shown that only a small proportion of the iron absorbed is excreted by the kidney, less than 1% of the dose administered. The pathway of Na⁵⁵Fe-[2-¹⁴C]EDTA absorption and excretion when administered orally was studied in swine. A certain proportion (about 5%) of the ⁵⁵Fe is split from the EDTA complex in the lumen of the gut, absorbed mainly from the pylorus and upper jejunum, transferred to plasma transferrin and then incorporated into the circulating hemoglobin. A small proportion of the iron absorbed, less than 1% of the dose administered, is excreted by the kidney, to a degree similar to that excreted by humans. The rest of the iron is eliminated in the feces, about 3% in a soluble form possibly still bound to EDTA and the greater part, about 92%, in an insoluble form. About 5% of the ¹⁴C is absorbed almost uniformly along the pyloric duodenal and jejunal mucosa, then transferred slowly to the plasma and excreted by the kidney within 48 hours. The rest of the ¹⁴C was excreted in the feces, about 80% in a soluble form and 20% in the insoluble fraction.