Dr Poonam Sharma
There are many questions that arise in the minds of the general public and patients whenever a doctor orders a CBC test. This article is an attempt to answer such queries and ease the anxiety of the patients on seeing the results.
Why is my CBC being done?
A complete blood count (CBC) is a commonly performed blood test that serves several purposes:
Overall Health Assessment: CBC is often included as part of a routine medical examination to assess a person’s general health. It can help identify conditions such as anemia (low red blood cell count) or leukemia (abnormal white blood cell count).
Diagnostic Tool: CBC is used to diagnose medical conditions by investigating the cause of specific symptoms. For example, if a person is experiencing weakness, fatigue, or fever, a CBC can provide valuable information to determine the underlying cause. It can also help identify the cause of symptoms like swelling, pain, bruising, or abnormal bleeding.
Monitoring Existing Conditions: For individuals with known medical conditions that affect blood cell counts, such as anemias, leukemias, or thrombocytopenia (low platelet count), regular CBC tests are performed to monitor the progression of the condition and evaluate the effectiveness of treatment.
Assessing Treatment Effects: Certain medical treatments, including medications or radiation therapy, can impact blood cell counts. CBC tests are used to monitor the effects of these treatments on blood cells and ensure they are within a safe and desired range.
By conducting a CBC, healthcare providers can gather important information about a person’s blood cell counts, which can provide valuable insights into their overall health, aid in diagnosing medical conditions, monitor existing conditions, and evaluate the impact of medical treatments.
What does my CBC measure?
The following measurements are usually mentioned in a CBC report:
Total leucocyte count (TLC)
Differential leucocyte count (DLC)
Red blood cell count
Mean corpuscular volume (MCV)
What tests of White blood cells are mentioned in a CBC report?
White blood cells (leukocytes) are an integral part of the immune system and have a vital role in defending the body against infections and foreign substances. A CBC test provides information about white blood cells through two main measurements:
Total Leucocyte Count (TLC): This measurement determines the total number of white blood cells present in a given volume of blood.
White Blood Cell Differential (DLC): The DLC measures the relative proportions or percentages of different types of white blood cells present in the blood sample. The five major types of white blood cells typically evaluated in a DLC are Neutrophils, Lymphocytes, Monocytes, Eosinophils and Basophils. Each type plays a role in protecting your body.
Alterations in the DLC can indicate specific infections, inflammatory conditions, or disorders of the immune system.
Tests of RBCs in CBC report?
Red blood cells are generated within the bone marrow and serve the crucial role of transporting oxygen throughout the body while eliminating carbon dioxide. A complete blood count (CBC) typically includes four measurements related to red blood cells:
-Red Blood Cell Count (RBC): This measurement determines the total number of red blood cells present in a given volume of blood.
-Hematocrit: Hematocrit signifies the proportion or percentage of blood volume occupied by red blood cells. It indicates the volume of red blood cells relative to the total blood volume and reflects their oxygen-carrying capacity.
-Hemoglobin: Hemoglobin is a protein present in red blood cells that binds with oxygen and carries it to tissues throughout the body. Hemoglobin measurement assesses the quantity of this oxygen-carrying protein within the red blood cell-Mean Corpuscular Volume (MCV): MCV is a measurement used to determine the average size of red blood cells. MCV provides information about the size of red blood cells and helps classify different types of anemia.
Platelet tests mentioned in a CBC report
Platelets are cellular components of the blood responsible for forming blood clots to halt bleeding. During a CBC test, the platelet count (PC) is a measurement that indicates the total quantity of platelets present in your blood sample.
What are the normal ranges of these tests?
Upon receiving your CBC test report, you will typically observe two columns: one indicating the “reference range” and the other displaying your individual results. If your results fall within the reference range, they are considered normal. However, if your results are higher or lower than the reference range, they are considered abnormal.
It’s important to note that different laboratories may employ varying methods when analyzing blood samples. Consequently, the specific reference range utilized will depend on the particular lab conducting your blood tests. Additionally, normal ranges can differ based on factors such as age, sex, and even the altitude of your residence.
Instead of providing a single specific number, a range is used for each measurement because the amounts can vary from person to person. This allows for a more comprehensive understanding of how your results compare to what is typically observed within a given population. It is recommended to consult with your healthcare provider for a thorough analysis and interpretation of your CBC test results.
Interpreting CBC Results
Here are some common causes for test results that deviate from the normal range:
-White blood cell tests: A low white blood cell count, known as leukopenia, can be attributed to autoimmune conditions, bone marrow diseases, or cancer. Certain medications can also lead to a decrease in white blood cell counts. Conversely, a higher than usual white blood cell count is commonly associated with infection, inflammation, or blood cancers. It can also be a reaction to medications or intense exercise.
-Red blood cell tests: Lower than usual measures of red blood cells indicate anemia. Anemia can be caused by factors such as low levels of specific vitamins or iron, as well as blood loss. Individuals with anemia may experience symptoms of weakness or fatigue, which can be attributed to the anemia itself or its underlying cause. Conversely, a higher than usual red blood cell count, as well as elevated hemoglobin or hematocrit levels, may indicate conditions like blood cancer or heart disease, a condition known as erythrocytosis.
-Platelet count: A low platelet count, known as thrombocytopenia, or a high platelet count, known as thrombocytosis, can signal an underlying medical condition or be a side effect of certain medications. When platelet counts fall outside the typical range, further tests are usually conducted to determine the cause. Individuals with very low platelet counts are at an increased risk of serious bleeding or bruising. In cases of extremely low platelet counts, platelet transfusions may be recommended by your doctor.
Note: Remember, these explanations are not exhaustive, and there may be other factors or conditions that can influence your CBC test results. It’s always best to seek professional guidance from your healthcare provider to fully understand and interpret your specific results.
(The author is Assistant Professor Department of Pathology AIIMS Vijaypur, Jammu)
Dr Poonam Sharma