A complete blood count (CBC) is a blood work that helps to evaluate the overall health status and determines a broad range of health conditions affecting the blood, including anaemia, infection, bleeding disorders and cancer.
CBC Test

This test measures several elements and features of blood including:

Red blood cells (RBC) that carry oxygen

White blood cells (WBC) that combat infection-causing pathogens

Haemoglobin, a protein compound that transports oxygen and nutrients in red blood cells

Hematocrit, the proportion of red blood cells to the plasma (fluid component) in the blood

Platelet, that helps in the blood clotting process

Any abnormal increase or decrease in cell count values may denote that a person is suffering from an underlying medical problem that needs further evaluation and treatment.

Why Complete Blood Count Test Is Done?

A complete blood count is one of the most common blood tests that’s done for several reasons, which include:

To determine the overall health: Your health care provider may suggest a complete blood count as part of a regular medical evaluation to monitor a person general health status and to screen for health disorders such as anaemia or leukaemia.

To diagnose a medical condition: The physician may suggest to do CBC if you are feeling weak, fatigue, recurrent fever, inflammation or bleeding. This test may help the physician to diagnose the underlying cause of these signs and symptoms.

Also Read: Anemia: 5 Awesome Natural Remedies To Boost Your Iron Levels

To evaluate a medical condition : If a person is diagnosed with any blood disorder that affects blood counts, then the physician may use CBC values to assess the problem.

To evaluate medical treatment: A complete blood count may be used to assess the health condition after having medications that may affect CBC values.

How It Is Done?

The blood sample is taken at any time during the day, the person can eat and drink normally before the test sample of blood is collected by inserting a needle into a vein in the arm and the blood sample is analysed.

What Do The Results Indicate?

The results of complete blood count above or below the normal values may denote health issues.

Red Blood Cell Count

The red blood cell count result comprises RBC, haemoglobin and haematocrit, the results of RBC are related as they evaluate each trait of your red blood cells. If the RBC measures are lower than you may have anaemia. This condition leads to fatigue and weakness. It is also caused due to low levels of certain vitamins, iron, blood loss or an underlying health condition. Whereas if the RBC count is higher or high haemoglobin or haematocrit levels could indicate a medical condition such as polycythemia vera or heart disease.

Red Blood Cells Normal Value:

Male: 4.35-5.65 million cells/mcL

Female: 3.92-5.13 million cells/mcL

Haemoglobin Normal Value:        

Male: 13.2-16.6 grams/dL

Female: 11.6-15 grams/dL

Hematocrit Normal Value:  

Male: 38.3-48.6 percent

Female: 35.5-44.9 percent

White Blood Cell Count (WBC)

A low white blood cell count (leukopenia) is caused by a health condition such as an autoimmune disorder that damages white blood cells, bone marrow problems or certain types of cancer. Aside from this, certain medication can also cause white blood cell counts to dropdown.

On the other hand, if the WBC count is higher than normal, then you may have an infection or inflammation or an immune system disorder or a bone marrow disease.

White Blood Cell Count Normal Value:

3,400 to 9,600 cells/mcL

Also Read: Blood Disorders: Types, Symptoms and Treatment

Platelet Count

A platelet count that’s lower than normal (thrombocytopenia) or higher than normal (thrombocytosis) is mostly an indication of an underlying medical problem or it may also be a side effect of medication. Generally, if the platelet count is outside the normal value, the doctor may suggest further tests to determine the cause.

Platelet Count Normal Value:

Male: 135,000 to 317,000/mcL

Female: 157,000 to 371,000/mcL


Complete blood count results that are outside the reference intervals may signify the presence of one or more health conditions or disorders. Furthermore, other tests are also done to help evaluate the cause of abnormal results. In most cases, a blood smear will be examined using a microscope to determine the appearance and physical features of the blood cells including size, shape and colour that may help to find out any abnormalities that may be present.