Magnesium and Platelet Function Testing

One heparin tube (4ml) and one hirudin tube (4ml) blood sample will be collected through standard venipuncture. After applying a tourniquet with moderate pressure around the arm of the patient's choice, skin will be disinfected over a suitable vein in the elbow or fore-arm. A hirudin and a heparin tube will be filled with venous blood through a single puncture with a 22 Ga needle (manufacturer, location). After release of the tourniquet, bleeding will be stopped by applying local pressure for 5 minutes with a sterile gauze.