Interference of heparin in carcinoembryonic antigen radioimmunoassays

A false Roche carcinoembryonic antigen (CEA) activity could be detected in all commercial and noncommercial heparin preparations we examined. The possibility of 'due to contamination' has been ruled out. Using the Roche procedure, heparin solutions, in the absence of CEA, gave positive CEA activity; on the other hand, no CEA activity was detected in solutions containing only heparin when the Abbott Kit was used. When heparin was present in specimens containing CEA, the Abbott Kit underestimated the CEA activity, whereas the Roche Kit gave false elevated values. However, the negative effect of heparin could be reduced by heat treatment in the presence of plasma proteins.