Serum Ferritin Iron in Iron Overload and Liver Damage: Correlation to Body Iron Stores and Diagnostic Relevance

The iron content of serum ferritin has been determined in groups of patients with normal or increased iron stores by using a technique of ferritin immunoprecipitation followed by iron quantitation with atomic absorption spectroscopy. The results were correlated to individual liver iron concentrations, measured non-invasively by superconducting quantum interference device (SQUID) biomagnetometry. A close correlation between serum concentrations of ferritin protein and ferritin iron was found (r = 0.92) in all groups of patients. However, the correlation between ferritin iron concentration and individual liver iron concentration was poor in patients with hemochromatosis (r = 0.63) and patients with beta-thalassemia major (r = 0.57). The degree of ferritin iron saturation was about 5% in iron-loaded patients, which contrasts with results in two recent studies but confirms older observations. In patients with liver cell damage, the ferritin iron saturation in serum was significantly higher than that found in groups with iron overload disease, probably indicating the release of intracellular iron-rich ferritin into the blood. The monitoring of patients undergoing bone marrow transplantation indicated that the release of iron-rich and iron-poor ferritin occurred during phases of hepatocellular damage and inflammation, respectively. We find the benefits of serum ferritin iron measurement to be marginal in patients with iron overload disease.