Complete Blood Count (CBC)

A complete blood count, or CBC, is very common and easy test that measures for certain disorders that can affect your health.

A CBC screens if there are any increases or decreases in your blood cell counts. Normal ranges of CBC vary depending on your age and your gender. Your doctor will inform you about normal value range for your age and gender.

A CBC can help diagnose a wide range of conditions, like anemia and infections, cancers etc.

The three basic types of blood cells

CBC test measures the three basic types of blood cells. Red blood cells, White Blood cells, Platelets. Changes in the blood cell levels can help doctor to evaluate your overall health and find out the disorders.

Red blood cells

RBC carries oxygen throughout your body and removes carbon dioxide. A CBC determines two components of your red blood cells:

  • hemoglobin: oxygen-carrying protein
  • hematocrit: percentage of red blood cells in your blood

White blood cells

White blood cells help your body fight infection. A CBC measures the number and types of white blood cells in your body. Abnormal increases or decreases in the number or types of white blood cells could indicate cancer, Infection or inflammation.


Any changes in platelet levels can have risk of excessive bleeding and can indicate a serious medical condition. Platelets help your blood clot and control bleeding.

When is a CBC ordered?

Your doctor may recommend a Complete blood count test as part of a routine checkup or if you have unknown symptoms such as bruising or bleeding .A CBC can help your doctor do the following.

  • Evaluate your overall health.
  • Diagnose a health problem
  • Monitor a health problem.
  • Monitor your treatment.

What happens during a CBC?

During a complete blood count test, a medical professional will draw blood from a vein, from the inside of your elbow or from the back of your hand. The test will take only a few minutes.

1.     First the lab technician cleans your skin with an antiseptic wipe

2.     Tie an elastic band around your upper arm to help the vein swell with blood

3.     Inserts a needle and collects a blood sample

4.     Removes the elastic band

5.     Covers the area with a bandage to stop bleeding if any

A blood test can be slightly uncomfortable. When the needle punctures your

What do the results mean?

Test results will vary based on your blood cell counts and different labs may have different ranges to deliver. Here are the normal results for adults,

Blood component

Normal levels

red blood cell

In men: 4.32-5.72 million cells/mcL
In women: 3.90-5.03 million cells/mcL


In men: 135-175 grams/L
In women: 120-155 grams/L


In men: 38.8-50.0 percent
In women: 34.9-44.5 percent

white blood cell count

3,500 to 10,500 cells/mcL

platelet count

150,000 to 450,000/mcL

If blood cell counts are too high or too low than this could be a signal of wide variety of conditions Specific tests are needed to diagnose a specific condition. Conditions that results an abnormal CBC and may need additional testing which includes:

  • Cancer
  • Heart Disease
  • Bleeding disorders
  • Iron and Vitamin Deficiencies
  • Infection
  • Bne Marrow Problems

If your CBC indicates abnormal levels, your doctor may prescribe another blood test to analyze better and diagnose the actual problem

Authenticated by:

Dr. Gaurav Sharma

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