Why Doctors Do Blood Tests

By Howard J. Bennett

You may not realize this, but there are three parts to a doctor’s visit. The first part is the medical history, when the doctor asks about your symptoms (if you’re sick) or general questions about school and other stuff (if it’s a regular checkup).

The second part of the visit is the physical examination. This is when the doctor listens to your heart and lungs, feels your belly and checks your ears and throat.

The third part of the visit includes shots and any tests to find out what’s wrong with you or to check some basic things such as vision and hearing. This might include a blood count.

If your doctor gets a blood test at a checkup, it’s usually to see if you are getting enough iron in your diet. At sick visits, doctors usually do blood tests to see if you have a viral or bacterial infection. There are different types of white blood cells in your body and certain ones become more active when you’re fighting a bacterial infection.

Kids often want to know if a blood test will hurt. The answer to that question is—it depends.

Some blood tests can be done with a finger prick, which feels like a quick pinch and doesn’t hurt much. Because the blood is taken from tiny blood vessels called capillaries, the person drawing your blood is unlikely to “miss” and have to stick you again.

If your doctor needs a larger amount of blood, the sample will have to be taken from a vein in the front of your elbow area. The downside of this test is that the person drawing your blood can sometimes miss the vein and may need to stick you again. If you hold still, that is less likely to happen.

The worst thing about a blood test is the anticipation that it’s coming. The best way to reduce this fear is to distract yourself before the poke. Here are some techniques that may work:

• Stare at an object in the room.

• Pinch yourself. (Because this hurts, you are less likely to feel it when the needle sticks you.)

• Listen to music.

• Watch a movie on an iPod, a smart phone or bring a DVD player to the office.

• Put a numbing cream on your arm. This is very effective, but must be applied 30 minutes before the blood is drawn.

Bonus Fact: In the old days, doctors thought people got sick because of an imbalance in their blood. They treated this by “bleeding” patients to remove the bad elements. Bleeding was done by cutting a vein or by applying leeches that sucked blood out of the patient’s body. This barbaric practice never cured anyone and in some cases killed patients because too much blood was drained from the bloodstream. Fortunately, the technique was abandoned a long time ago. So the next time your doctor wants a little of your blood, be glad you weren’t born in the Middle Ages!

 

© 2012 Howard J. Bennett. All Rights Reserved.
(First published in the Washington Post 6/7/10.)

For more KidsPost articles and lots of other cool stuff,
please visit Dr. B’s website at  www.howardjbennett.com.

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