repeatedly clench the fist to permit visualization of the vein. The contraction of forearm muscles during repeated fist clenching causes release of potassium, since there is a reduction in the intracellular electronegativity during the depolarization of muscle cells, which favors the release of potassium rather than its uptake.47 Repeated fist clenching during phlebotomy after application of the tourniquet can cause a 1- to 2-mEq/L (1- to 2-mmol/L) increase in potassium. In 1 study, an increase in the potassium level as much as 2.7 mEq/L (2.7 mmol/L) was noted in a healthy subject due to fist clenching during phlebotomy.48 Application of the tourniquet for more than 1 minute and up to 2 minutes can cause a 5% increase in the total cholesterol level, which can increase by 10% to 15% if the tourniquet is left on for 5 minutes.22,23,41