The complete blood count (CBC) is among the most common lab tests. CBC test looks at red blood cells, white blood cells, and platelets. Doctors prescribe the test to screen for various conditions, including anaemia, infection, inflammation, and bleeding disorders.

In the following section, Newtown Clinic, the best blood test lab in Kolkata, explains everything you need to know about CBC.

What is a CBC Test?

A complete blood count (CBC), also known as full blood count or full blood exams, is a group of blood tests that evaluates blood cells. CBC gives information about the following types of cells found in the blood:

  • white blood cells (WBCs)
  • red blood cells (RBCs)
  • platelets

Why is This Test Done?

According to the best blood test lab in Newtown, CBC tests are performed to detect many health issues, including anaemia, infections, clotting problems, immune system disorders, and blood cancers.

They are also used to monitor existing conditions or evaluate the effectiveness of a specific treatment.

CBC is not a definitive diagnostic test. Upon seeing the report, a doctor interprets the results according to the patient’s symptoms, medical history, and other test results and, if necessary, orders additional tests.

What is Tested in the CBC?

A CBC test includes the following:

  • WBC count
  • WBC differential
  • RBC count
  • Haemoglobin
  • Hematocrit
  • RBC indices
  • Reticulocyte count
  • Platelet count

White Blood Cell (WBC) Count

WBC count test measures the number of white blood cells present in the blood. White blood cells fight bacteria, viruses, and other foreign invaders and protect the body against infections and diseases.

Low WBC levels indicate that the body doesn’t have adequate resources to fight against infections properly. On the other hand, high WBC levels suggest that the body is currently fighting a disease. High WBC levels can also indicate chronic inflammation in the body.

White Blood Cell (WBC) Differential

The presence of a normal percentage of different types of WBC is also essential for a person’s health. If the WBC levels increase or decrease, it is necessary to check which particular cells are the cause.

This test identifies and measures the amount of 5 primary WBCs types:

  • Neutrophils – These cells help fight infection by ingesting microbes and releasing enzymes that kill them.
  • Lymphocytes – These cells produce antibodies and kill cancer and virus-infected cells.
  • Monocytes – These cells engulf and destroy foreign material.
  • Eosinophils – These cells fight infections caused by parasites.
  • Basophils – These cells are involved in the inflammatory responses.

Red Blood Cell (RBC) Count

RBC test counts the number of red blood cells (RBCs) in your blood. The primary function of RBCs is to supply oxygen to tissues.

Low levels of RBCs suggest anaemia. Causes of low RBC includes bleeding, injuries, malnutrition, particular nutrient deficiencies, liver, kidney, or bone marrow disorders.

A high RBC count indicates that the body is trying to compensate for the lack of oxygen. Some causes of high RBC include high altitude, smoking, lung and heart disease. Disorders of kidney or bone marrow can also increase RBC count.

Red Blood Cell Indices

These tests provide information about the physical properties of red blood cells like their size/volume, the average amount of haemoglobin in the cells and the percentage of blood cells made up of haemoglobin. The higher or lower value of these properties indicates different conditions like anaemia, kidney disease, and nutritional deficiencies.


The test aims to measure the amount of haemoglobin in the blood to help diagnose anaemia and polycythemia. Haemoglobin carries oxygen to the rest of the body from the lungs and transports carbon dioxide from tissues back into the lungs to be exhaled.

Both low and high level of haemoglobin is bad as both decrease the oxygen supply in tissues, although by different mechanisms. A high haemoglobin can also increase the risk of high blood pressure and blood clots.


This test measures the RBC percentage in the blood. Haematocrit can be high if a person is dehydrated, overweight, smokes, or drinks alcohol. It can also increase due to a wide range of other medical conditions. High levels of haematocrit can increase the risk of blood clots, stroke, and heart disease. Low haematocrit can be caused due to anaemia, thalassemia, or other diseases and disorders.

Reticulocyte Count

This test measures the number of reticulocytes in the blood. Reticulocytes are newly formed red blood cells in the bone marrow. and the test is prescribed to evaluate bone marrow function.

Platelet Count

This test aims to measure the number of platelets in the blood. Platelet facilitates blood clots. Lower platelet count can cause problems with blood clotting, which can lead to excessive bleeding and prevent wounds from healing properly. Platelet levels may reduce due to medications, or underlying diseases, such as lupus or leukaemia. Platelet levels can increase during infections and inflammatory disorders.

Mean Platelet Volume (MPV)

The test is performed to measure the average size of the platelets found in your blood and assess problems with platelet production in the bone marrow or platelet destruction.

Platelets grow in size when the body produces an increased amount of platelet.

Visit Newtown Clinic to get affordable blood tests in Newtown.