Variability in hepatic iron concentration measurement from needle-biopsy specimens

Quantitative measurement of hepatic iron by biochemical analysis of liver biopsy samples is required to assess hepatic iron stores accurately. Cirrhotic livers, however, contain variable amounts of fibrous tissue and the distribution of iron within the hepatic parenchyma is not always uniform. The aim of this study was to assess the variability in hepatic iron concentration measurement from needle-biopsy specimens.

The livers from eight patients with cirrhosis selected because of elevated serum ferritin were obtained at the time of liver transplantation (n = 6) or at autopsy (n = 2). Multiple needle biopsies were done, and hepatic iron concentration was measured by atomic absorption spectroscopy. The hepatic iron index was calculated as iron concentration divided by age.

Four cases had a mean hepatic iron index above 2.0, in the range of that reported in patients with homozygous genetic hemochromatosis, whereas the other four had an hepatic iron index of less than 2.0. The intra-individual coefficient of variation for hepatic iron concentration ranged from 11.3 to 43.7%, averaging 24.9%. The coefficient of variation was smaller in biopsy samples > 4 mg dry weight than in samples < 4 mg (19.8% vs 28.6%, p < 0.05). Histological examination of surgical biopsies from these livers showed large amounts of fibrous tissue, and inhomogeneous distribution or iron in the hepatic parenchyma.

This study demonstrates an important variability in the measurement of hepatic iron content from needle biopsy specimens in patients with severe cirrhosis.