Cytochemical methods for copper. Semiquantitative screening procedure for identification of abnormal copper levels in liver.

Three previously described histochemical methods for the localization of copper were examined for applicability in the semiquantitative evaluation copper levels in human tissue. Liver tissue obtained at autopsy was stained using dimethylaminobenzylidene rhodanine, rubeanic acid, and diethyldithiocarbamate procedures. The effects of method and time of fixation, staining, incubation time, and variations in procedures were evaluated. Copper levels in tissues examined were determined using atomic absorption spectroscopy. Each staining method was evaluated for sensitivity, reproducibility, and linearity. The rhodanine method was found to produce the most reproducible results, and a linear relationship between microscopical evaluation of the stain and actual tissue copper levels was observed. It was concluded that the rhodanine copper method is applicable for the semi-quantitative evaluation of tissue copper and provides a satisfactory screening method for the identification of abnormal tissue copper levels.