However, the concentration of ATP, ADP and AMP in the blood is highly dependent on how blood is handled after venipuncture and which vacutaner is used. Plasma concentrations are often overestimated due to red blood cell lysis during sample preparation (centrifugation) and sample collection (EDTA vacutubes). On the other hand, various metabolic processes in the blood and ATP-ases break down ATP, so if the blood is not cooled properly after collection, values are underestimated. In our case, because of the care taken in collection and fractionation of the blood, the ATP in plasma was not detectable, which also confirms the work of Junger et al that the plasma ATP concentration in healthy people (33±20 nM) is still well below detection limit of NMR.