What Is a CBC Test?


The Complete Blood Count (CBC) test helps detect various medical conditions, including anaemia, infections, blood clotting disorders, and specific cancers. Typically integrated into routine health checkups, a CBC test supplies healthcare providers with essential information regarding your overall health. Your doctor will assess these findings within the context of your medical history to come up with a diagnosis and create a treatment plan. CBC test prices might vary slightly based on the laboratory and your symptoms.

Why Is It Done?

A CBC blood test is done for several important reasons in the field of medicine:

General Health Assessment:

A CBC test is often part of a routine checkup to assess a person's overall health. It provides a snapshot of the health and composition of the blood, which can reveal underlying medical conditions even if there are no obvious symptoms.

Diagnosis of Medical Conditions:

CBC results can help diagnose various medical conditions, including:

Anaemia: Low red blood cell count or haemoglobin levels.

Infections: Elevated white blood cell count (indicating an immune response).

Bleeding Disorders: Abnormal platelet counts or clotting problems.

Inflammatory Conditions: Elevated white blood cell count may indicate inflammation.

Certain Cancers: CBC results, especially when combined with other tests, can suggest the presence of certain blood cancers like leukaemia or lymphoma.

Monitoring Health Conditions: A CBC test can help monitor disease progression and treatment effects for individuals with known medical conditions. For example, it can track how well a person with anaemia responds to iron supplements.

Preoperative Evaluation: Surgeons may request a CBC before surgery to assess a patient's blood count and clotting ability. This information can help them make decisions about surgery and anaesthesia.

Medication Management: Some medications can affect blood counts. Regular CBC monitoring may be necessary for patients taking certain drugs, such as chemotherapy agents, to ensure they do not develop dangerous side effects.

Evaluate Symptoms: When an individual experiences symptoms such as fatigue, weakness, unexplained bruising, or recurrent infections, a Complete Blood Count (CBC) can serve as one of the primary tests to pinpoint potential underlying reasons for these issues.

Assess Response to Treatment: Patients undergoing treatments like chemotherapy or radiation therapy undergo regular CBC tests to evaluate how effective the treatment is and to monitor any changes in their blood cell counts.

Blood Donations: A CBC is often performed to ensure the donor's or recipient's blood is suitable for the procedure before donating blood or receiving a blood transfusion.

Normal CBC Values

The CBC normal ranges are:

Red Blood Cells (RBC)

  • Male: 4.5 to 6.0 million cells/mcL (cubic millimetre)
  • Female: 4.0 to 5.5 million cells/mcL

Haemoglobin (Hb):

  • Male: 13.8 to 17.2 grams/dL (grams per deciliter)
  • Female: 12.1 to 15.1 grams/dL

Hematocrit (Hct):

  • Male: 38.3% to 48.6%
  • Female: 35.5% to 44.9%

White Blood Cells (WBC): 4,000 to 11,000 cells/mcL

Platelets: 150,000 to 450,000 cells/mcL

Mean Corpuscular Volume (MCV): 80 to 100 femtoliters (fL)

Mean Corpuscular Haemoglobin (MCH): 27 to 33 picograms (pg)

Mean Corpuscular Haemoglobin Concentration (MCHC): 32 to 36 grams/dL

Red Cell Distribution Width (RDW): 11.5% to 14.5%

What Do the Results Mean?

Interpreting the results of a CBC test includes analysing various components of the blood to assess a person's overall health and detect potential medical conditions. Listed below is what different CBC test results may indicate:

Red Blood Cells (RBC):

Low RBC Count: This may suggest anaemia, which can be caused by factors such as iron deficiency, vitamin deficiency, chronic disease, or blood loss.

High RBC Count: This might indicate conditions like polycythemia vera, where the bone marrow generates too many red blood cells.

Haemoglobin (Hb):

Low Haemoglobin: Indicates anaemia or another condition affecting the body's ability to carry oxygen.

High Haemoglobin: This could be due to dehydration or medical conditions like polycythemia vera.

Hematocrit (Hct):

Low Hematocrit: Suggests anaemia or blood loss.

High Hematocrit: This can be seen in conditions like dehydration or polycythemia.

White Blood Cells (WBC):

Low WBC Count (Leukopenia): This may indicate a weakened immune system, bone marrow disorder, or some viral infections.

High WBC Count (Leukocytosis): Often a sign of infection or inflammation. Certain blood disorders or medications can also cause it.


Low Platelet Count (Thrombocytopenia): May result from conditions like immune disorders, bone marrow disorders, or excessive bleeding.

High Platelet Count (Thrombocytosis): Can be associated with various conditions, including inflammation, infection, or bone marrow disorders.

Mean Corpuscular Volume (MCV):

Low MCV: Often seen in iron-deficiency anaemia or other types of anaemia.

High MCV: Can indicate conditions like vitamin B12 deficiency or folate deficiency anaemia.

Mean Corpuscular Haemoglobin (MCH):

Low MCH: Typically associated with iron-deficiency anaemia.

High MCH: Less common, but it can occur in certain types of anaemia or haemoglobin disorders.

Mean Corpuscular Haemoglobin Concentration (MCHC):

Low MCHC: May suggest conditions like iron deficiency anaemia or thalassemia.

High MCHC: Less common, but it can be seen in some haemoglobin disorders.

Red Cell Distribution Width (RDW):

High RDW: Suggests variability in red blood cell size, which can be seen in various types of anaemia.

What May the Results Indicate?

Complete Blood Count (CBC) results can provide valuable information about your overall health and potential medical conditions. Here are some possible interpretations of CBC results and the conditions they may indicate:

Low Red Blood Cell Count:

Anaemia: Low RBC count can suggest anaemia, possibly due to iron deficiency, vitamin deficiency (e.g., B12 or folate deficiency), chronic diseases, bone marrow disorders, or blood loss.

Low Haemoglobin:

Anaemia: Low haemoglobin levels are a common sign of anaemia, which can have various causes.

Low Hematocrit:

Anaemia: A low hematocrit often accompanies anaemia, indicating lower blood volume or red blood cell production.

High Red Blood Cell Count:

Polycythemia: An elevated RBC count may be due to conditions like polycythemia vera, a disorder characterised by an overproduction of red blood cells.

High Haemoglobin (Hb) or Hematocrit:

Dehydration: Elevated levels may result from dehydration, where the blood becomes more concentrated.

Low White Blood Cell Count (WBC) (Leukopenia):

Weakened Immune System: Low WBC count can indicate a weakened immune system, which may be caused by certain infections, autoimmune diseases, or bone marrow disorders.

High White Blood Cell Count (WBC) (Leukocytosis):

Infection: Elevated WBC count is often a response to infection or inflammation.

Leukaemia: In some cases, very high WBC counts may be a sign of leukaemia or other blood disorders.

Low Platelet Count (Thrombocytopenia):

Bleeding Disorders: Low platelet counts can increase the risk of bleeding and may be caused by conditions like immune thrombocytopenic purpura (ITP) or certain medications.

Bone Marrow Disorders: Some bone marrow disorders can lead to decreased platelet production.

High Platelet Count (Thrombocytosis):

Inflammation: Elevated platelet counts can be associated with inflammatory conditions.

Iron Deficiency: It can sometimes be seen in cases of iron deficiency anaemia.

Abnormal Mean Corpuscular Volume (MCV), Mean Corpuscular Haemoglobin (MCH), or Mean Corpuscular Haemoglobin Concentration (MCHC):

Anaemia Subtypes: These indices can help differentiate between different types of anaemia, such as iron-deficiency anaemia, vitamin-deficiency anaemia, or certain inherited haemoglobin disorders like thalassemia.

High Red Cell Distribution Width (RDW):

Anisocytosis: Elevated RDW suggests variability in red blood cell size and may be seen in various types of anaemia.

When to See a Doctor?

Consult a doctor if you experience persistent or unexplained symptoms, as early detection and treatment can often prevent more serious health issues. Routine checkups, even when feeling well, are crucial for preventive care and identifying potential problems. If your medical tests show abnormal results or if you have chronic conditions, adhere to recommended monitoring schedules to manage your health effectively.

Regular medication management and follow-up appointments are vital. Life changes like altered risk factors, family medical history, or mental health concerns also warrant seeking medical advice. Injuries requiring immediate attention should not be overlooked. Prioritizing regular healthcare visits and addressing health concerns promptly is a proactive approach to maintaining good health and well-being.