Determination of Hepatic Iron Concentration in Fresh and Paraffin-embedded Tissue

Abstract

Serum iron, transferrin, transferrin saturation, and ferritin are used to determine the iron status of an individual. When iron overload is suspected because of abnormal iron indices, the accurate determination of hepatic iron content (HIC) is important for the diagnosis of genetic hemochromatosis (GH). The measurement of HIC and the calculation of the hepatic iron index (HII), defined as HIC/age, enables the discrimination between patients with homozygous GH and those with either the heterozygous form of the disease or secondary causes of hepatic iron deposition. Despite the advent of DNA genotyping for the diagnosis of GH, liver biopsies are sometimes required for histological grading of liver disease and biochemical analysis to quantify the HIC. Genotyping will now identify many homozygotes before the development of clinical symptoms and an increased HII, and may reduce the need for obtaining a liver biopsy in some patients. However, in our experience the number of specimens submitted for HIC analysis has not changed over an 8-month period since the introduction of genotyping for GH. Two techniques are used for the determination of liver iron content. The more common technique is histological grading of stainable iron, using Prussian blue dye; the other technique is the quantitative chemical determination of iron. The latter requires the liver sample to be homogenized or digested with acid before iron determination by either colorimetry or atomic adsorption spectroscopy. The diagnosis of GH can be established reliably using the HII calculated from the hepatic iron concentration determined by atomic absorption spectroscopy. …