Blood Test
A blood test is a lab analysis of things that may be found in your blood. You may
have blood tests to keep track of how well you are managing a condition, such as diabetes
or high cholesterol. You may also have them for routine checkups or when you are ill.
Blood tests are very common. They are ordered by healthcare providers to:
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Find out how well organs, such as your kidneys, liver, heart, or thyroid are working
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Help diagnose diseases, such as cancer, diabetes, heart disease, and HIV/AIDS
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Find out if your medicine is working to make you better
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Diagnose bleeding or clotting disorders
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Find out if your immune system is having problems fighting infections
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Diagnose anemia, such as iron-deficiency anemia, pernicious anemia, aplastic anemia,
or hemolytic anemia
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Find variations in hemoglobin, such as hemoglobin S, C, or E, which are common in
people of African, Mediterranean, or Southeast Asian background
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Monitor chronic health conditions and diseases
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Find health problems in their early stages
You have the right to know why a blood test has been ordered and how much it will
cost. Ask your healthcare provider if you are not sure why they want you to have the
test.
Types of blood tests
These are common blood tests:
Blood tests can give your healthcare provider a lot of information. They can see if
certain elements in your blood are in a normal range. But in many cases, blood tests
are only part of the information your healthcare provider needs to make a diagnosis
of a health condition. You might need to have some other types of tests as well.
Preparing for a blood test
For most kinds of blood tests, you don't need to prepare. These tests are to see what
your blood is like under normal conditions.
For some blood tests, you will have to fast for a certain amount of time before the
blood test. The fasting time may vary depending on the test. These tests are often
scheduled for early in the morning.
Your healthcare provider will let you know if you need to fast before a blood test.
The procedure
To test your blood, a technician called a phlebotomist will use a needle to take a
sample of blood. Tell the technician if the sight of needles makes you nervous. They
can help you feel more at ease. You can also look away during the procedure, and bring
a family member or friend to help distract you.
In most cases, the sample is taken from a vein in your arm. You will be seated or
lying down. You may be asked to make a fist. The technician will tie a rubber band
around your arm. Once they see a vein, the technician will clean the area and then
insert the needle. You might feel a small prick or stinging sensation. Once the technician
has drawn enough blood, they will take the needle out and put an adhesive bandage
over the site. You may be asked to press firmly on the site to stop any bleeding.
After the procedure
Your blood sample will be sent to a lab. Trained technicians then look for the information
the healthcare provider has ordered. This may take a day or up to a week or more.
Ask your healthcare provider’s office how you should expect to find out about the
results. In many cases, the results will be posted online in the provider's web portal.