Various laboratory tests have been developed to assess iron overload. While not widely available, they may hold promise of providing additional clinical information.
- Serum ferritin iron may be less susceptible than serum ferritin to confounding factors such as inflammation (1).
- Serum transferrin receptor concentration has been used to detect both iron deficiency and excess iron. In the presence of iron overload, cells downregulate transferrin receptor expression, and therefore serum transferrin receptor concentration would be expected to be reduced (2).
- Labile plasma iron (LPI) quantifies the oxidative activity of the patient's plasma-borne NTBI. In theory, this test can be used as a direct measure of iron overload. One approach to measuring LPI is to measure the reactive radicals generated in the subject's blood by exposure to ascorbate, compared to those generated after the addition of a chelating agent (which blocks the oxidative activity of the NTBI) (3).
- Directly chelatable iron (DCI) is not a test for iron overload per se, but rather an experimental assay for assaying the plasma pool of non-transferrin-bound iron (NTBI).