Diagnosis and clinical evaluation of iron overload

Diagnostic evaluation of the various forms of iron overload requires information about the total amount and distribution of iron stores. Direct information on the quantity of storage iron can be obtained only by its mobilization in response to repeated phlebotomy or after dilution of a labelled iron test dose in the total body iron pool. Both approaches are cumbersome and time-consuming and are suitable only for research purposes. Detailed information on the amount and distribution of tissue iron in iron overload can be obtained from biopsy specimens of the major iron storage organs such as the liver and bone marrow. However, the invasive nature of these procedures limits their clinical usefulness. Indirect measures, such as serum iron concentration, TIBC saturation, serum ferritin, chelate-induced urinary iron excretion or intestinal iron absorption, and ferrokinetic measurements may provide useful information on the amount of total body iron reserve. However, they all have important limitations in their diagnostic use for evaluating iron overload. The most suitable indirect storage iron index among these methods is the ferritin assay, which has a well established place in the diagnosis of iron overload and monitoring of the effect of therapy. Recent developments in physical methods such as CT, SQUID and NMR have significantly improved the applicability of these techniques for non-invasive measurement of liver iron. It is expected that quantitative measurement of hepatic iron stores will soon be integrated into the diagnostic procedures available by imaging techniques such as CT and NMR. In combination with screening parameters such as serum ferritin and TIBC saturation these new but expensive diagnostic tools may simplify and shorten the diagnostic process and may also be useful for monitoring the treatment of iron overload by phlebotomy or chelating drugs.