Effect of in vitro hemolysis on assay of plasma catecholamines and DOPA.

I analyzed for free and sulfate-conjugated catecholamines and DOPA (3,4-dihydroxyphenylalanine) in four aliquots of a single plasma pool with use of Upjohn's "Cat-A-Kit" (catecholamines radioenzymatic assay kit [3H]. One aliquot was a clear plasma control; the others were supplemented with different concentrations of lysed human erythrocytes, to investigate possible interference by hemolysis with analysis for norepinephrine, epinephrine, dopamine, or DOPA in plasma. I observed no statistically significant difference that could be attributed to the degree of hemolysis between control and treatment groups for DOPA or any catecholamine fraction. Hemolysis in plasma from improper collection or processing techniques apparently does not preclude accurate and precise quantitation of free or sulfate-conjugated catecholamines or DOPA with the Cat-A-Kit.