What Is a Complete Blood Count (CBC) Test and Why Is It Done?
Introduction
The CBC is one of the most widely performed tests in medicine and is often ordered by primary care physicians for patients—especially when they have a fever, cough, any reason for concern or are following up on a previous illness. For many people, the CBC will be the first type of blood test they have ever received; however, most individuals do not understand the significance of the CBC and how it informs their health and treatment.
The CBC provides a physician with a snapshot of the patient’s overall health by providing a foundation from which several other tests may be done. It can help to identify a number of potentially life-threatening diseases including infections, anemia, inflammatory diseases, autoimmune diseases/blood problems such as lymphomas/leukemia, etc. In addition, the CBC may identify certain diseases/conditions before the patient ever develops any signs or symptoms so that treatment can begin earlier.
Table of Content:
- Introduction
- What Is A Complete Blood Count (CBC)?
- Why Is There A Recommendation For A CBC Test By A Doctor?
- Understanding the Different Components of a CBC
- What Are Some Conditions Found on a CBC?
- Can a CBC Alone Tell Me if I Have an Illness?
- Why Routine CBC Testing is Important
- Conclusion
What Is A Complete Blood Count (CBC)?
A complete blood count is a laboratory test which evaluates the different types of cells in the body. There are many different types of cells; however, each type of cell plays an important role to overall physical health and wellness.
The CBC test consists of measurements of:
- Red Blood Cells (RBCs)
- White Blood Cells (WBCs)
- Hemoglobin (HgB)
- Hematocrit (Hct)
- Platelets
- Red cell indices including MCV (mean corpuscular volume), MCH (mean corpuscular hemoglobin), and MCHC (mean corpuscular hemoglobin concentration).
Together, these values give doctors a detailed picture of your blood health and can provide clues about various underlying conditions.
Why Is There A Recommendation For A CBC Test By A Doctor?
One reason why the CBC is so common is that it can answer many questions with just one sample of blood. Your doctor may order to have a CBC performed if any of the following occur:
- Staying tired
- Having continual fever or repeated infections
- Feeling weak
- Feeling light-headed
- Losing weight when you did not try to lose weight
- Getting bruises easily
- Bleeding too much
- Having difficulty breathing
- Having pale skin
Additionally, a doctor will often perform a CBC whenever you go in for an annual check-up, before having surgery, during pregnancy, or if you are being monitored for any ongoing medical problems.
Understanding the Different Components of a CBC
Red Blood Cells (RBC's)
Red Blood Cell’s job is to deliver oxygen from your lungs to all areas of your body. If your RBC’s are too low, your body does not get enough oxygen, causing you to be tired, weak, dizzy or short of breath. RBC’s can be elevated due to dehydration, smoking, or due to lung problems; it may also indicate that you should be investigated for other medical problems.
Haemoglobin
Haemoglobin is the protein inside red blood cells that carries the oxygen. Haemoglobin that is too low is considered one of the most major signs of anaemia. Conditions that cause low levels of haemoglobin include iron deficiency, B12 deficiencies, chronic disease, bleeding, or inherited disorders.
The body’s immune system consists of white blood cells (leukocytes), which fight against bacteria, viruses, fungi, and other infections. An increase in the number of white blood cells is indicative of:
infections caused by bacteria;
- inflammation;
- physical stress; or
- particular blood disorders.
Decreased levels of the white blood cell count happen as a result of:
- viral infection;
- autoimmune disease;
- treatment with certain drugs; or
- bone marrow disease.
Patients with low levels of white blood cells will be more susceptible to developing an infection.
Platelets
Platelets are responsible for helping blood to clot whenever there has been trauma or injury to tissue.
A low number of platelets may create risk for excessive bleeding/bruising, while a high number of platelets can sometimes represent signs of inflammation or other disease processes. Close monitoring of platelet counts is usually necessary for patients with diseases such as:
- dengue fever;
- certain types of infection; and/or
- blood disorders
Haematocrit and Red Cell Indices
CBC results will also include measurements of hematocrit — which is the percentage of the total number of cells that video examples of red blood cells, and their respective value for mean corpuscular volume (MCV); mean corpuscular hemoglobin (MCH); and mean corpuscular hemoglobin concentration (MCHC). These three numbers play a role in the identification of different types of anemia. In particular, they are used to help determine whether the underlying cause of the anemia was iron deficiency anemia, vitamin deficiency anemia, chronic disease anemia, or genetically inherited anemia.
What Are Some Conditions Found on a CBC?
- While a CBC alone does not provide a definitive diagnosis, it can still provide invaluable information about your starting point.
- Conditions that can be found on a CBC include:
- Iron deficiency anemia
- Vitamin B12 deficiency
- Folate deficiency
- Bacterial and viral infections
- Allergy
- Chronic inflammation
- Issues with blood clotting
- A bone marrow disorder
- Certain cancers such as leukemia
- Dehydration
- A problem with the Immune System
Will I Have to Fast Before a CBC?
For most tests, including a CBC test, fasting is typically not required, so you may eat and drink as you normally would before providing a specimen.
If your health care provider is also going to perform some additional testing, such as a Lipid Profile or Fasting Blood Sugar, your health care provider may give you specific fasting instructions for those tests. You should always follow the directions provided by your health care provider.
Can a CBC Alone Tell Me if I Have an Illness?
It is commonly believed that a normal CBC result means there are no health problems.
A CBC test can provide useful information about your blood cells, but cannot diagnose every medical condition. For example, thyroid tests, diabetes tests, liver function tests, kidney tests, and vitamin and mineral tests usually require additional blood tests for diagnosis. A physician usually interprets CBC results with your overall medical history to arrive at an accurate diagnosis.
Why Routine CBC Testing is Important
It’s common for people to develop health issues over time, without any outward signs or symptoms. For example, one may ignore feelings of tiredness, decreased energy, and frequent illnesses (e.g., colds) as being caused by stress or lack of sleep. However, there may actually be some underlying condition that is leading to these symptoms (e.g., anemia, an infection, etc.).
Routine CBC testing permits you to discover these underlying illnesses early on and allows for easier and often more effective treatments. Children, women who are pregnant and period of old age as well as those who suffer from chronic illnesses often benefit from this type of routine testing.
Conclusion
A CBC is not just a normal lab test; it is a good starting point for doctors to use in diagnosing many diseases and determining your overall level of health. Knowing about the things that are measured in a CBC will allow you to understand why CBC tests are performed on patients often, and why routine health checks should be performed as a preventive care measure.
Sikund Diagnostics offers patients a comprehensive range of CBC tests that use current laboratory technology and meet reliable laboratory reporting standards, enabling providers to make appropriate clinical decisions. Regular blood testing, paired with timely medical care, will greatly assist you in maintaining a healthy body along with catching potential issues prior to becoming serious.
