Accumulation of iron and iron compounds in liver tissue. A comparative study of the histological and chemical estimation of liver iron.

Abstract

Unsatisfactory results obtained by histological evaluation of liver tissue in iron loading diseases prompted us to study the distribution of the total liver iron, haem iron and ferritin iron in post mortem human liver tissue from two different sites of the same liver. The total liver iron content was measured by flameless atomic absorption spectroscopy in native liver homogenates and in acid digested liver tissue from 60 consecutive autopsies, and the results from the two methods were compared. From the standard deviation of the duplicate analyses, it was deduced that the liver iron is possibly inhomogeneously distributed. The CVduplo (22%) of total iron, measured in acid digested tissue was higher than the CVduplo (14%) of total iron in homogenates from liver tissue from which non-homogenized tissue e.g. vessel walls, fibrotic tissue, had been removed. The CVduplo of ferritin iron and haem iron in liver homogenate was 14% and 30% respectively. The ferritin iron increased with an increasing total iron content until saturation of ferritin iron appeared to be reached at 2.5 micrograms ferritin iron per mg liver protein. When the results of total non-heam liver iron measurements are expressed properly (amount of iron per amount of homogenized liver protein), the distribution of iron is found to be homogeneous in both normal and pathological liver tissues. It was concluded that the estimation of liver iron content by visual microscopic evaluation is unsatisfactory, and that more reliable results are obtained by atomic absorption spectrophotometry.