How to Read Your CBC (Complete Blood Count) Results

A Complete Blood Count (CBC) is one of the most frequently ordered blood tests worldwide. It gives your doctor a snapshot of the cells circulating in your blood and can detect a wide range of conditions, from anaemia and infection to leukaemia. Understanding what each component means empowers you to have more informed conversations with your healthcare provider.

Haemoglobin (Hgb) and Haematocrit (HCT)

Haemoglobin carries oxygen from your lungs to every cell in your body. The normal range for adult males is 13.5–17.5 g/dL, and for adult females 12.0–15.5 g/dL. Values below these ranges indicate anaemia — your tissues are not getting enough oxygen. Haematocrit is the percentage of your blood that consists of red blood cells; it mirrors haemoglobin trends.

• Mild anaemia (Hgb 10–12 g/dL): fatigue, shortness of breath on exertion
• Moderate anaemia (Hgb 8–10 g/dL): significant symptoms, clinical evaluation needed
• Severe anaemia (Hgb < 8 g/dL): may require hospitalisation or transfusion

Red Blood Cell Indices: MCV, MCH, MCHC

These indices describe the size and haemoglobin content of your red cells and help determine the type of anaemia. MCV (Mean Corpuscular Volume) measures red cell size in femtolitres (fL). Low MCV (< 80 fL) is called microcytic — most often due to iron deficiency or thalassaemia. High MCV (> 100 fL) is macrocytic — caused by B12 or folate deficiency, hypothyroidism, or alcohol.

White Blood Cell Count (WBC)

The normal WBC range is 4.0–11.0 × 10³/µL. Elevated WBC (leukocytosis) most commonly indicates bacterial infection, inflammation, or stress — but very high counts may suggest leukaemia. Low WBC (leukopenia) can result from viral infections, autoimmune disease, or bone marrow suppression.

• Neutrophils (50–70%): first responders to bacterial infection
• Lymphocytes (20–40%): elevated in viral infections (EBV, CMV)
• Monocytes (2–8%): elevated in chronic infection, TB, monocytic leukaemia
• Eosinophils (1–4%): elevated in allergies and parasitic infections
• Basophils (0–1%): rarely elevated; seen in chronic myeloid leukaemia

Platelet Count

Platelets are tiny cells that form clots to stop bleeding. The normal range is 150–400 × 10³/µL. Thrombocytopenia (low platelets, < 150) increases bleeding risk. In dengue fever, platelets can fall dramatically — counts below 50 require close monitoring. Thrombocytosis (high platelets) is often reactive (infection, iron deficiency) but can also indicate myeloproliferative disorders.

Key Takeaways

A CBC provides a wealth of information in a single test, but individual values must always be interpreted in the context of symptoms and clinical history.

• Always compare to the reference range on your specific lab report
• A single abnormal value is less concerning than a pattern of abnormalities
• Trends over time are as important as a single reading
• Always discuss abnormal results with your doctor