Complete Blood Count (CBC)

Regarded as one of the most common tests prescribed by doctors, a Complete Blood Count (CBC) stands as a standard medical test that is focused on evaluating the overall health of a patient and detecting different health parameters like infection, anemia, inflammation, bleeding or cancer. The core task of the CBC test is that it evaluates the cells that circulate the blood. These cells are produced by the bone marrow and get released in the bloodstream as required. The test is carried out by using an automated instrument to understand the concentration level of the different components present in the blood. Some of the core reasons that a doctor advises to proceed head with a CBC test includes:

• If the patient is suffering from continuous ill/ fever or any infection.
• If the patient gets tired too often or is facing continuous weight loss.
• If the patient shows any sign of cancer including bruising or bleeding, etc.

Components of a Complete Blood Count Test

The complete blood test calculates the essential parameters of the blood cells. The core components include White Blood Cells (WBC), Red Blood Cells (RBC), and Platelets (PLT). Let’s understand them and their sub-components that get evaluated during the CBC test.

1. White Blood Cell (WBC or Leukocyte count)

The white blood cells are a part of the blood that fights infection. The presence of WBC in the blood is essential to maintain a healthy state and to fight infections or any other causes of injury. There are five different types of WBCs, namely, neutrophils, lymphocytes, basophils, eosinophils, and monocytes, each present as per their relevant stable numbers. The difference in the count of different types of WBCs might cause allergies, bacterial infection, leukemia, etc.

2. Red Blood Cell (RCB or Erythrocyte count)

The red blood cells are produced in the bone marrow, and along with their maturity state, they are released into the bloodstream. The average lifespan of an RBC is 120 days, and thus, the bone marrow keeps on generating new RBCs to replace the old ones. The RBCs are made up of a protein, called hemoglobin, which carries the oxygen throughout the body and hematocrit (proportion of blood in RBCs)

3. Platelet

Also known as thrombocytes, these are particular cell fragments of more giant cells called megakaryocytes that play an essential role in blood clotting. If a person suffers an injury, the platelets become activated, and they clump together at the bleeding site. The person who lacks platelets holds an increased risk of excessive bleeding. The Mean Platelet Volume (MPV) measures the average size of the platelets in the blood volume.

What is the Purpose of a CBC Test?

During a physical examination, a CBC test is prescribed to check a variety of reasons which includes:

• Review the overall health status
• To screen a wide range of conditions and diseases
• To monitor the situation or effectiveness of treatment after a diagnosis gets established.
• To monitor a medical treatment that is known to affect blood cells like chemotherapy or radiation therapy.

The Sample Collection Process

The CBC test is performed by collecting a blood sample of the patient. The lab technician will draw blood from a vein from the inside of the patient’s elbow or from the back of the hand by inserting a needle. Once the blood sample is collected, it is being sent to the ab for further analysis.

Pre-Test or Precautions

Before proceeding ahead for a CBC test, make sure to take care of the following:

• Wear a short-sleeve shirt or a T-shirt.
• Eat and drink regularly before the CBC test is performed.

However, there can be a condition wherein the doctor might ask you to fast before the test gets conducted. That might turn out to be a possibility is the blood sample will be used for any additional test.

Interpretation of the Results

The values and their explanations are highlighted below.

Substance	Range	Meaning of a Low Count	Meaning of a High Count
White Blood Cells (WBC)	4,300-10,800 cells per cubic millimeter(cmm).	Autoimmune disease, bone marrow failure, viral infections	Infection, inflammation, leukemia, stress, intense exercise.
Red Blood Cells (RBC)	4.2-5.9 million cells per cmm	Deficiency of iron, Vitamin B12, bone marrow damage, leukemia, acute or chronic blood loss, RBC hemolysis	Dehydration, renal problems, pulmonary disease, congenital heart disease, polycythemia vera
Platelets	150,000-400,000 per cmm	Bone marrow failure, chemotherapy, viral infections, lupus, sequestration in the spleen	Leukemia, myeloproliferative disorders, inflammatory conditions
Mean Platelet Volume (MPV)	6-12 femtoliters (a minute fraction of a litre).	Aplastic anemia, thrombocytopenia	Certain inherited disorders
Hemoglobin	For men: 13.8-17.2 grams per deciliter (g / dL) For women: 12.1-15.1 grams per deciliter (g / dL	Deficiency of iron, Vitamin B12, bone marrow damage, leukemia, acute or chronic blood loss, RBC hemolysis	Dehydration, renal problems, pulmonary disease, congenital heart disease, polycythemia vera
Hematocrit	For men: 45%-52% For women: 37%-48%	Deficiency of iron, Vitamin B12, bone marrow damage, leukemia, acute or chronic blood loss, RBC hemolysis	Dehydration, renal problems, pulmonary disease, congenital heart disease, polycythemia vera

 

In case if you have been asked to proceed ahead with a CBC test, then it is advisable to continue forward at the earliest to get a better clarification regarding your health.