You know the drill – when you have blood drawn, they put the tourniquet in place around your upper arm and tell you to clench your fist a few times to get the blood flowing.  Turns out that may NOT  be the best idea, since fist clenching can create falsely high potassium levels, a finding that could lead to unnecessary further tests and treatment for impaired kidney function.  A better technique is to gently close your hand when the needle is being inserted and then open it.  Close, don’t pump, your fist.  The tourniquet, of course, should be loosened once the blood starts flowing.  Having your arm at chest height, the way you will at most testing centers, helps too.  If they don’t sit you down in that special armrest chair at the doctor’s office, politely ask them to do so.  Share with the phlebotomist things that have worked for you in the past – tapping into the hand, a butterfly device, or a very thin needle.  The pros recommend you look away during the draw and do some meditative breathing.  Holding your breath can lead to fainting.
Before you get to the office, you can do yourself a favor if you drink quite a bit of water, as much as you can tolerate.  Hydration will get things going.  If you really have problems, consider wearing one of those disposable heating pads (designed for the lower back) wrapped around your elbow area on the way to the test.  The warmth will increase circulation.  If you don’t have directions not to, take your multivitamin and drink orange juice religiously on the days before your test to avoid bruising, but try not to take them before the test on “the day of.”  You don’t know what will throw off the blood work.  A bag of frozen peas on the area after you get home will also help with bruising.  All the advice above goes double for blood donation, and we’ll have an article soon on the health benefits of blood donation.