How Blood Test Done?
My doctor wants me to have a blood test, but I am scared stiff. What actually happens during a blood test? Does it hurt?
The doctor may take the blood in the surgery or you may be asked to go to a nearby pathology clinic. Either way, the sample will be sent to a laboratory for analysis, unless a relatively simple test is required, in which case the doctor may have the necessary equipment in the surgery to perform the analysis (eg. for blood sugar).
Blood is extracted by inserting a hollow needle into a vein and allowing an amount of blood to flow into an attached tube. The blood will usually be taken from a vein at the bend in your elbow, but if that is not sufficiently prominent, the nurse may try your forearm or the back of your hand. It takes only a minute or so. Once the nurse has sufficient blood for the tests that have been ordered, the needle will be withdrawn and a dressing or cotton wool pressed on to the point of entry to stop the flow. You will need to leave it in place for half an hour or so until the blood clots naturally.
Sometimes the blood can be taken at any time of the day, but if the test is to measure your metabolism (how your body converts food into energy), the test must be performed in the early morning after a 12 hour fast, or at particular times after you have eaten a certain measured amount of food.
Blood tests to measure the amount of certain drugs in the system are also taken at specific times after the tablets are swallowed.
Blood tests hurt far less than a normal injection such as a flu shot because nothing is injected. If you do not watch the nurse, you will barely notice the discomfort, which will be no worse than having someone pinch your skin.
I had a blood test at a local shopping centre that showed my urea to be 10.9 instead of between 2.5 and 7.9. What does this mean?
Random blood tests at shopping centres are notoriously unreliable, particularly for substances such as cholesterol. I assume that in your case, the high urea reading was an isolated finding on a machine that scans for many different substances.
A urea reading of 10.9 is certainly high, and the first thing you should do is to arrange for your GP to repeat the test using a recognised laboratory. This reading can then be compared to other results, the results of a physical examination, and your medical history, to make an appropriate diagnosis.
Elevated urea levels are usually found in kidney disease, but other tests are usually abnormal as well.
Don’t start worrying until you confirm that there really is a problem.