L02 — January 2011 — Blood Basics

Intro: Being stuck with a needle is no fun, but blood tests are a very important part of your general physical examination. The information doctors get from blood tests provides information on whether or not your body is functioning normally. So, what exactly are they looking for in your sample of blood? Let's take a look at blood test basics.

Ouch. That needle can sting. But your blood holds important clues to your health.

For the routine blood tests, we generally do what we call a complete blood count.

Dr. Rajiv Pruthi says a complete blood count measures certain components in your blood. If the numbers are off balance, it means something's not right. For instance, if your hemoglobin, present in red blood cells, is low, you have anemia. If your white cell count is high, you could have an infection or other more-serious conditions. Basically, blood tests are screening tests.

Which, in conjunction with the patient history and physical exam, will lead you to a diagnosis if there are abnormalities.

Here are the basic components of your blood. Blood is made in the bone marrow. It's like a factory that produces red blood cells, white blood cells and platelets. Red blood cells are transport molecules. They carry oxygen from the lungs to the rest of your body. They also carry carbon dioxide away from tissue to your lungs to breathe out. White blood cells are part of the immune system. It's their job to fight off infection. Platelets are tiny particles that scan blood vessels looking for holes. If they find any, they form clots.

If, after a blood test, the amount of these cells in your blood is too high or too low, your doctor may order further testing to find out why.

We know there are many diseases that we deal with, and we know what those diseases do to the blood, platelets, hemoglobin and white cells. But sometimes patients may have minimal or no symptoms and the first sign is abnormalities on your complete blood count.

Yes, that needle may pinch, but Dr. Pruthi says it's important to get a complete blood count once a year. And if there are any issues, it's important to find out why.

For Medical Edge, I'm Vivien Williams.

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You might wonder why they use veins in your arms to draw blood for most blood tests. Well, veins are easier to access, and it's less painful to puncture a vein than an artery.

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