According to a study by Nick Neuwinger et al. (October 2019), Underfilling of vacuum blood collection tubes leads to increased lactate dehydrogenase activity in serum and heparin plasma samples. Both types of plasma used have elevated lactate dehydrogenase activity, however, the LD activity for Heparin Plasma is higher than Serum Plasma. This makes me curious about the differences in the effects of the two types of plasma on the results of testing lactate dehydrogenase in underfilled tubes.