CBC

What is Complete Blood Count (CBC) Test?

Complete blood count, or CBC, is a common blood test that provides important information about the composition of the blood. It measures various parameters of the blood, such as red blood cells, white blood cells, and platelets. The test helps to evaluate overall health and detect potential underlying medical conditions. 

CBC test is a routine test suggested by the doctor as a diagnostic test to assess the blood's cellular makeup and identify any abnormalities.

What is the Purpose of the Test?

A CBC test is commonly prescribed for various reasons, including: 

1. Routine Check-ups: Doctors may order a CBC test as part of a routine health examination to assess the overall health status.
2. Symptoms Evaluation: If a person is experiencing unexplained symptoms such as fatigue, weakness, frequent infections, bruising, or prolonged bleeding, a CBC test can help identify potential causes.
3. Monitoring Chronic Conditions: Individuals with chronic conditions like diabetes, kidney disease, or heart disease may undergo regular CBC tests to monitor their health-related parameters and the impact of treatments.
4. Preoperative Assessment: Prior to surgery, a CBC test is often performed to evaluate the blood's ability to clot properly and detect any underlying conditions that may affect the surgical procedure.
5. Follow-up Care: If a person has a known blood disorder or is undergoing treatment for a specific condition, regular CBC tests may be prescribed to monitor your progress and adjust the treatment plan accordingly.

What Does Complete Blood Count (CBC) Test Measure?

Red Blood Cell Measurements

RBC, also called erythrocytes, carries oxygen from the lungs to the tissues and organs in the body. A Complete Blood Count (CBC) test involves various fundamental measurements of red blood cells (RBCs):

1. RBC count: It is the total number of RBCs in the blood.
2. Hemoglobin: It measures the amount of hemoglobin (oxygen-carrying protein) that is found inside RBCs.
3. Hematocrit: It measures the proportion of the total blood volume that consists of RBCs.

A Complete Blood Count (CBC) also provides details about the size and characteristics of red blood cells (RBC). These details, known as RBC indices, are of several types:

1. Mean corpuscular volume (MCV): A measurement of the average size of RBC.
2. Mean corpuscular hemoglobin (MCH): It is the average amount of hemoglobin inside each RBC.
3. Mean corpuscular hemoglobin concentration (MCHC): It is a calculated measurement of how concentrated hemoglobin is within RBC.
4. Red cell distribution width (RDW): It is a measurement of the variation in the size of the RBC.

White Blood Cell Measurements

White blood cells (WBCs), also known as leukocytes, play an important role in the body's immune system.  A CBC test includes measures of 5 different types of WBCs:

1. Neutrophils: They make up the greatest percentage of WBCs and are produced by bone marrow to fight inflammatory and infectious diseases.
2. Lymphocytes: They are of two types, B-cells and T-cells. They are found primarily in the lymph system and fight bacteria and other pathogens in the blood.
3. Monocytes: They work with neutrophils to fight infections and other illnesses while removing damaged or dead cells.
4. Eosinophils: They are activated in response to allergies and some types of infections.
5. Basophils: They are involved in the early identification of infections as well as wound repair and allergic reactions.

Platelet Measurements

Platelets, also called thrombocytes, are small cell fragments in the blood that are essential for blood clotting.  When there is an injury and bleeding begin, PLT helps stop bleeding by sticking to the injury site and clumping together to form a clot.

A standard parameter of the CBC test is the PLT count, which is the number of PLT in the blood sample.

When Does One Need a Complete Blood Count Test?

A CBC test is often suggested by doctor for various reasons, including:

1. Routine Health Checkups: Many doctors include CBC as a part of routine checkups to assess overall health and detect potential issues.
2. Unexplained Symptoms: If a person experience unexplained symptoms such as fatigue, weakness, pale skin, shortness of breath, bruising, or frequent infections, a CBC may be suggested to help identify the underlying cause.
3. Monitoring Chronic Conditions: Doctor may suggest CBC test to individuals having chronic medical conditions such as anemia, leukemia, or autoimmune disorders to monitor their condition and advise treatment plans as needed.

What Preparations Are Required for Complete Blood Count (CBC) Test?

In most cases, a CBC test does not require specific preparations. However, it is advisable to inform the healthcare provider about any medications a person is taking, as certain medications can affect the test results. Additionally, if a person has had a recent blood transfusion, it's essential to let the healthcare provider know, as this can influence the interpretation of the CBC test.

Generally, a person can have the CBC test done at any time during the day, and fasting is not typically required. However, the healthcare provider may give specific instructions based on the unique circumstances.

It's crucial to follow the doctor’s guidance regarding the CBC test, as accurate results are essential for an appropriate diagnosis and treatment plan.

Interpreting Complete Blood Count (CBC) Test Results

Red blood cell count, hemoglobin and hematocrit

The results of these three are related because they each measure a feature of red blood cells.

Lower than usual measures in these three areas are a sign of anemia.

Anemia has many causes such as:

1. Low levels of certain vitamins or iron
2. Blood loss
3. Any other medical condition

People with anemia might feel weak or tired.

A red blood cell counts that's higher than usual is known as erythrocytosis. A high red blood cell counts, or high hemoglobin or hematocrit levels could point to a medical condition such as blood cancer or heart disease.

White Blood Cell Count

A low white blood cell count is known as leukopenia. It can be due to different medical conditions such as:

1. Autoimmune disorder that destroys white blood cells
2. Bone marrow problems
3. Cancer

Certain medicines also can cause a drop in white blood cell counts.

The white blood cell counts that's higher than usual is most commonly due to:

1. An infection or inflammation
2. An immune system disorders
3. Bone marrow disease.
4. Blood cancer

Platelet Count

A platelet count that's lower than usual is known as thrombocytopenia. The lower count can be due to infection like dengue. If it's higher than usual, it's known as thrombocytosis. Either can be a sign of a medical condition or a side effect from medicine.