Radio iron is a tool which makes iron absorption studies quite accurate in dogs and reasonably satisfactory in human beings. This method is vastly superior to others previously used.
Normal human pregnancy without significant anemia may show active radio iron absorption—16 to 27 per cent of iron intake. The pregnant woman as a rule shows 2 to 10 times the normal absorption of radio iron.
Diseased states in which iron stores are known to be very abundant—pernicious anemia, hemochromatosis, familial icterus, and Mediterranean anemia —show very little absorption, probably less than normal. This is in spite of a severe anemia in all conditions except hemochromatosis.
Chronic infections in spite of anemia show no utilization of radio iron, whether it may be absorbed or not.
Leukemia shows little utilization of radio iron in red cells in spite of absorption (autopsy), probably because of white cells choking the red marrow.
Polycythemia shows very low values for iron absorption as do normal persons. Two pregnant women showed only normal iron absorption.
We believe that reserve stores of iron in the body, rather than anemia, control iron absorption. This control is exerted upon the gastro-intestinal mucosa which can refuse or accept iron under various conditions.