Complete Blood Count (CBC)
There is very little chance of a problem from
having a blood sample taken from a vein.
- You may get a small bruise at the site. You
can lower the chance of bruising by keeping pressure on the site for several
- In rare cases, the vein may become swollen after the
blood sample is taken. This problem is called phlebitis. A warm compress can be
used several times a day to treat this.
- Ongoing bleeding can be a
problem for people with bleeding disorders. Aspirin, warfarin (such as Coumadin), and
other blood-thinning medicines can make bleeding more likely. If you have
bleeding or clotting problems, or if you take blood-thinning medicine, tell
your doctor before your blood sample is taken.
A complete blood count (CBC) gives important information about the
kinds and numbers of cells in the blood, especially
red blood cells ,
white blood cells , and
platelets. A CBC helps your doctor check
any symptoms, such as weakness, fatigue, or bruising, you may have. A CBC also
helps him or her diagnose conditions, such as
anemia, infection, and many other disorders.
The normal values listed here—called a reference range—are just a guide. These ranges vary from lab to lab, and your lab may have a different range for what's normal. Your lab report should contain the range your lab uses. Also, your doctor will evaluate your results based on your health and other factors. This means that a value that falls outside the normal values listed here may still be normal for you or your lab.
Normal values for the complete blood count (CBC) tests depend
on age, sex, how high above sea level you live, and the type of blood sample.
Your doctor may use all the CBC values to check for a condition.
For example, the red blood cell (RBC) count, hemoglobin (Hgb), and hematocrit
(HCT) are the most important values needed to tell whether a person has anemia,
but the red blood cell indices and the blood smear also help with the diagnosis
and may show a possible cause for the anemia.