Absorption of Iron Compounds from the Upper Part of the Small Intestine

Abstract

The intubation technique of Miller and Abbott 1 , 2 , 3 as modified by Groen 4 has been used in the present investigation to study the absorption of ferrous, ferric, and complex iron compounds from a 50 cm. loop of the small intestine in man.

Each iron salt after being dissolved in 100 ml. of distilled water was introduced into the isolated segment of gut of a fasting subject in such amounts that between 80 and 100 mg. of iron were present.

After 30 minutes the solution was aspirated and washing of both the blocked segment of intestine and the stomach was commenced and was continued for 30 minutes.

Aliquot amounts of both intestinal contents and washings were analyzed for total iron by the method of Taylor and Brock. 6 When the intestinal contents contained organic debris of a nature that made accurate sampling impossible, the intestinal contents were partially digested by standing for 48 hours after mixing with an equal volume of concentrated sulphuric acid.

With ferric salts (ferric ammonium sulphate, ferric chloride and ferric nitrate) 20 to 35% of the iron was recovered. With the ferrous salts (ferrous sulphate, ferrous ammonium sulphate and ferrous chloride) 60 to 76% of the iron administered was recovered. With ferric ammonium citrate 100% was recovered. Dr. Wilfrid Owles 11 in this laboratory, using a 3-lumen tube and a completely isolated segment of intestine, obtained similar recoveries for ferrous sulphate and ferric ammonium citrate, while Abbott and Miller reported 3 100% recovery with ferric ammonium citrate. If the difference between the amount of iron ingested and that recovered, were assumed to be the amount absorbed, the conclusion would be that ferric salts were better absorbed than ferrous salts and that ferric ammonium citrate was not absorbed at all.