Why the study?
Does the ethylenediamine method compare favorably to the trihydroxyindole method for quantitating plasma catecholamines?
Does the ethylenediamine method compare favorably to the trihydroxyindole method for quantitating plasma catecholamines?
Both ethylenediamine and trihydroxyindole methods are accurate for quantifying plasma catecholamines, provided samples are properly handled (e.g., cooled in ice water) to prevent loss to blood cells.
Both methods show accuracy for added catecholamines in animal samples; leaves open human clinical validation and optimal handling protocols.
Comparative studies reveal that the ethylenediamine and the trihydroxyindole method when employed as suggested are suitable for assessing sympatho-adrenal activation under various stressful conditions that are accompanied by release of catecholamines into the circulation. Both methods are very accurate in quantitating epinephrine or norepinephrine that has been added to plasma or whole blood, although recovery from blood is less, owing mainly to some association of catecholamines with formed elements, primarily erythrocytes. Use of sodium thiosulfate in the ethylenediamine procedure minimizes association of catecholamines with formed elements. If blood samples are cooled in ice water when collected, association of catecholamines with blood cells can be further reduced. In the trihydroxyindole method, unless tubes containing blood samples are immediately immersed in ice water, a significant amount of catecholamines will disappear from plasma, because of this association of catecholamines with cells.
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Manger et al. (1969) studied this question.
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