March 1987

Blocking of Iron Absorption by a Preliminary Oral Dose of Iron

Author Affiliations

From the Department of Hematology, Division of Medicine, Walter Reed Army Institute of Research, Washington, DC. Dr Crosby is presently with the Chapman Regional Cancer Center, Joplin, Mo.

Arch Intern Med. 1987;147(3):489-491. doi:10.1001/archinte.1987.00370030093018

• Using a small-dose iron tolerance test (ITT) in mildly irondeficient healthy adults, we have examined the phenomenon of mucosal block. First proposed and demonstrated by Hahn et al with radioiron, "mucosal block" describes diminished avidity for iron of the intestinal mucosa following an orally administered blocking dose. In the ITT, the index of absorption is an increase in plasma iron concentration, rather than retained radioactivity. The absorption of a blocked 10-mg test dose of iron was compared with that of a 10-mg control dose given to the same subject. Both 60- and 30-mg blocking doses of iron resulted in diminished absorption of the test dose. The refractory state of the intestine lasted as long as 24 hours.

(Arch Intern Med 1987;147:489-491)