What is a Blood Test?

Red blood cell tests determine the amount of hemoglobin in the body.
A blood sample for a blood test can be taken from either an artery or a vein.
A blood sample for a test can be taken from either an artery or a vein.
Doctors will perform many tests using blood samples to gather the information they need.
In the most common type of blood test, blood is taken from a vein.
A diagram showing different types of white blood cells. A blood test can provide a white blood cell count.
A blood test is a useful tool to help doctors check for harmful organisms in the blood.
Blood samples can be viewed under a microscope.
Article Details
  • Written By: Garry Crystal
  • Edited By: Niki Foster
  • Last Modified Date: 06 August 2014
  • Copyright Protected:
    2003-2014
    Conjecture Corporation
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Blood is made up of different cells and other compounds. These include proteins and various salts. If your blood becomes infected by organisms, you can become ill. A blood test is a very useful tool that enables a doctor to check for harmful organisms in your blood.

Blood consists of two main elements. The liquid part is called plasma and the other elements are the cells. Doctors perform several tests with blood samples to get the information they need. These include a blood smear test and measurement levels of the cells. In a blood smear, blood is placed on a slide so that doctors can look at the blood under a microscope. They can see the cells up close and check for harmful organisms.

A blood sample for a blood test can be taken from either an artery or a vein. In the most common type of blood test, blood is taken from a vein. If the blood sample needed is very small, then a prick to the tip of a finger will allow enough blood to be taken. If the blood is taken from an artery or vein, then a needle is used. It is usually quite painless with only a small amount of discomfort.

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A blood test allows the doctor to look at the different type of cells in the blood. Red blood cell tests are the most important. The red blood cell test finds out how much hemoglobin there is in the body. Haemoglobin is vital as it carries oxygen around the body. If a person is suffering from anemia, then their hemoglobin count will be lower than normal.

The second blood test is the white blood cell test. The doctor needs to work out how many different types of white blood cells a patient has. Due to bacterial infection, the level of white blood cells may vary. When a person has autoimmune problems, in which the antibodies that should fight diseases attack the body instead, the white cell count may be low. Viral infections can also be a cause of low white blood cell count.

Another blood test is testing the platelet level. Platelets are small cells that coagulate when you have an injury. They form the basis of a blood clot to stop blood from flowing if you cut yourself. If you have low platelet levels, you can be vulnerable to excess bleeding. If the blood test shows a higher than normal level of platelets, you may be more vulnerable to excessive clotting.

Another blood test can be conducted to determine if the patient is suffering from coagulation disorders. A coagulation problem means that blood either doesn't clot properly or clots too well. Coagulation problems can sometimes be hereditary or may be due to liver problems. Blood tests are a very helpful and commonly used procedure. They enables the doctor to make a more specific diagnosis of a patient's illness.

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Discuss this Article

anon334782
Post 5

My mother had spinal cord tuberculosis with the d1 and d2 bones of spinal cord curved. She has been on medications for the past 22 months. How can we check if her medicines should be stopped? Can anyone suggest any blood tests?

anon243012
Post 4

What if your white blood count is high?

anon13823
Post 3

i have a 6 month old kitten and she has bad teeth but all else is fine with her. She went to see the vet last week and he said that she had a slight fever and took blood from her. This test is a white little plastic meter that had a light blue result.

What is that meter? I never saw it before and is it accurate? What color is it supposed to change to?

anon11690
Post 2

I found a website where you can find out what your blood type is in a few minutes at home. the kits are used in hospitals in Germany and is approved by their national FDA equivalent. Kits are very inexpensive and service is great.....a small piece of advice to save you money!

anon402
Post 1

What are the acceptable or normal levels that determine Pancreatitis.

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