Effect of protamine sulfate on the aca heparin assay.

Fig. 1 . Effect of increasing amounts of protamine sulfate on the ace measurement of hepann in whole blood (1 USP unlt/mL) The protam,ne/hepann ratio is based on the assumption that 0.01 mg of protamine neutralizes 1 unIt of hepaiin. The measured hepaiin concentration is shown as a percent of anti-factor Xa activity relative to baseline (no added protamine) determined in each experiment. The results of four separate expeilments are shown; aS data for each concentration measured are inCluded. For replicate samples, the average is plotted, wIth vertical bars gMng the range of measurements, and the number of data points at each protaznine/ hewn ratio is shown by each point The solid line represents the best least-squares fit for each concentration of heparin; the bmken line represents least-squares approximation of anti-factor Xa effect with increasing protamine concentration