THE ORDER OF DRAW OF BLOOD SPECIMENS INTO ADDITIVE CONTAINING TUBES DOES NOT AFFECT POTASSIUM AND CALCIUM MEASUREMENTS

The effect of order of draw when taking blood into tubes containing ad ditive was investigated in 47 medical inpatients; 12 of these patients acted as a control group. The samples were analysed in the order in w hich they were withdrawn. The results of potassium and calcium concent rations did not differ significantly between groups. Manufacturers rec ommend a specific order of draw when taking blood using vacuum based b lood collection systems, which are routinely used in many hospitals. T he results of this study, however, show that order of draw has no effe ct on calcium or potassium concentrations.