Kinin activation as a predictive assay for adverse reactions to radiographic contrast medium.

The rate of conversion in vitro, of prekallikrein to kallikrein has been measured in 74 reactors to contrast medium and 70 controls. The conversion rate is significantly more rapid in reactors than controls. There was no difference in C1-esterase inhibitor and factor XII levels between reactors and controls. This retrospective investigation suggests that prekallikrein/kallikrein conversion rate may form the basis of a test for differentiating between reactors and non-reactors.