Enzyme activity can be measured in plasma, leukocytes, or dried blood spots. For plasma, please send 5-10 ml of whole blood in a green top (sodium heparin) tube OR plasma can removed from spun down sample and sent frozen. For leukocytes, please send 5-10 ml of whole blood in a green top (sodium heparin) tube. For dried blood spot collection, a minimum of three circles need to be filled in. Each circle should contain one drop of blood (about 100 microliters). See the link below for additional sample collection and handling instructions.