CBC – What Purpose Does it Serve?

Complete blood count test

When you visit your doctor with some illness, what is the first test that your doctor recommends you? It is CBC or Complete blood count. This is one of the most common tests that even your family doctor might advise you for a routine checkup and to see if your illness is the cause of some underlying infection. But contrary to the popular belief that CBC is a normal blood test to measure the hemoglobin level and WBC count, there is actually a lot more than a CBC test can reveal about your health.

What is CBC?

Blood is primarily composed of red blood cells, white blood cells, and platelets. A CBC is a blood test that determines the blood cell counts. If the count is either too high or too low than the normal count, it indicates an abnormal health condition. However, the test results are subjective to age and gender. Doctors usually recommend a CBC to determine many health conditions like anemia, infection, inflammation and how certain treatments and therapies are affecting your blood.

It also explains the underlying health reasons behind symptoms like fever, weakness, fatigue and bruising.

Also if you are having a blood condition like thalassemia, this test will keep a record of that and if the medications are working fine.

How does CBC determine your health status?

The Complete Blood Count (CBC) can give you an overall status of your health and helps the doctor to determine if you need any further specific tests.

WBC count 

White Blood Cells help you to fight infections. If you have any infection or inflammation internally, the high WBC count will reveal it to your doctor. But if the count is below the normal levels, it means that your body is susceptible to infections.

An abnormal count of WBC could also be a sign of cancer.

RBC count

The red blood cells carry oxygen to the cells and tissues while filtering the carbon dioxide. A low RBC count means that you are anemic or have some other health condition.

 Haemoglobin count 

 Haemoglobin is the protein that holds the oxygen in the blood. An abnormal Hb count means:

  • Anemia
  • Abnormal blood loss
  • Lack of cell production in the bone marrow
  • Kidney disease
  • Nutritional deficiency
  • Lung disease
  • Congenital heart disease


This test determines the average size of your red blood cells. If the size of the cells is bigger than normal, it might indicate that you have a folate and Vitamin B12 deficiency. A smaller size of the red blood cells indicates that you could have a type of anemia called sickle anemia.

Platelet count 

Platelets help the blood to clot. An abnormal platelet count indicates:

  • Thrombocytopenia
  • Enlarged spleen
  • Leukemia
  • Benign reaction to a surgery, infection or medications

When does a doctor order a CBC?

If you are down with prolonged fever, have unexplained symptoms of continuous or intermittent bleeding, the doctor usually recommends a CBC test. Your doctor will be able to determine the following with a CBC:

  • Unexplained health symptoms like tiredness, weakness, bruises and swelling, fever, redness, and bleeding require a CBC to check for an underlying health condition
  • If you have a certain hematological condition like thalassemia, hemophilia, sickle cell disease, congenital anemia or others
  • Certain medications and treatments like chemotherapy affects the blood cell count and a regular CBC is required to monitor
  • As part of a routine health checkup

Go for CBC tests at regular intervals to keep a track of your health and wellness.

Also, Read:

Kidney Function Test: Everything You Need to Know

Liver Function Test: Everything You Need To Know!





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