Simplified Methods of Collecting and Processing Whole Blood for Quantitation of Plasma Catecholamines

Abstract

Abstract : A more liberal and less constrained handling of plasma norepinephrine (NE) and epinephrine (EPI) samples simplifies analysis and improves laboratory efficiency. We tested their stability in heparin or EDTA plasmas alone or combined with the antioxidant glutathione at 24 C or following long-term storage at -70 C. NE and EPI measured by high-pressure liquid chromatography (HPLC) with electrochemical detection are stable in heparinized plasma for 24 hours at 24 C (<6% degradation/d). In EDTA plasma, NE and EPI levels decrease less than 10% after 6 hours at 24 C but decay by 50% between 6 and 24 hours. At -70 C, NE and EPI in heparin or EDTA plasma are stable for 8 months, and the addition of antioxidant has no effect. Whole blood anticoagulated with heparin or EDTA does not alter plasma NE over the initial 6 hours at 24 C. We conclude that simple heparinization of human venous blood provides optimal conditions for quantitation of the in vivo concentration of plasma NE and EPI. Reprints.