Iron Transport

Iron in intestinal mucosal cells or stored in the liver (see below) may be transferred into the blood for transport to other tissues.

The iron (III) storage form must be reduced to iron (II) in order to cross the plasma membrane.

In the blood, iron (II) is reoxidized to iron (III) by ferroxidase II.

Iron (III) is carried by the serum protein, transferrin.

Transferrin contains two sites that bind iron (III) tightly.

Normally

This means that transferrin is normally only about 1/3 saturated with iron (the summary of saturation in the list above indicates that about six out of every 18 sites are occupied), and there is a substantial unsaturated plasma iron binding capacity. An unexpected influx of iron can be handled easily.

The iron binding capacity of serum is of clinical interest. It is accounted for almost entirely by transferrin.

There are three components to the iron binding capacity of serum.

Iron binding capacity is used in the differential diagnosis of certain diseases.

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Last modified 7/22/97

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