Cytogenetic effects of contrast material in patients undergoing excretory urography.

Acentric chromosome fragments produced in cells by irradiation or other agents give rise to micronuclei in daughter cells. The micronuclei can be counted readily in large numbers of cells which provides a sensitive measure of chromosome aberrations. Previous studies have shown that the presence of contrast material enhances the radiation-induced yield of micronuclei in vitro. This may be due to the dose enhancement effect and the chemical action of contrast media or their derivatives. Micronuclei were scored in peripheral blood lymphocytes obtained from 26 patients before and after excretory urography (ExU). The results show a consistent and significant increase in the counts after ExU amounting to about one third of the counts blood samples before the examination. We have also measured radiation exposures in this group and estimated an average exposure to the circulating lymphocytes of about 0.2R (0.52 X 10(-4) C/kg). We conclude that the contrast medium contributed significantly to the increase in micronuclei.