A CBC (complete blood count) test is a blood test that measures your red blood cells, white blood cells, haemoglobin and platelets. It helps detect anaemia, infections, inflammation and some blood disorders. It is one of the most commonly ordered tests and is part of almost every routine health checkup.
What does the CBC test measure?
Your blood carries three main types of cells, and a CBC counts and describes each of them from a single small sample.
- Red blood cells (RBCs) and haemoglobin: RBCs carry oxygen from your lungs to every organ, using a protein called haemoglobin. Low values usually point to anaemia, which is very common in India, especially among women.
- Red cell indices (MCV, MCH, MCHC, RDW): These describe the size and haemoglobin content of your red cells. They help a doctor tell apart iron deficiency (small cells) from vitamin B12 or folate deficiency (large cells).
- White blood cells (WBCs) and differential count: WBCs fight infection. The differential splits them into neutrophils, lymphocytes, monocytes, eosinophils and basophils. Raised neutrophils often point to bacterial infection; raised eosinophils can suggest allergy or worm infestation.
- Platelets: These help your blood clot. Low platelets are watched closely during dengue fever, a common reason Indian doctors order repeat CBCs.
- Haematocrit (PCV): The share of your blood made up of red cells.
Doctors order a CBC to investigate tiredness, fever, unexplained bruising or weight loss, and to monitor people on medicines that can affect blood counts.
CBC normal range (adults)
Women 12.0–15.0 g/dL
Women 3.8–4.8 million/µL
Women 36–46%
Lymphocytes 20–40%
Monocytes 2–10%
Eosinophils 1–6%
Basophils below 2%
(150,000–410,000/µL)
Ranges vary between labs and methods. Always compare your result with the reference range printed on your own report.
What abnormal results can mean
- Low haemoglobin or RBCs: Can suggest anaemia from iron, B12 or folate deficiency, blood loss or chronic disease.
- High WBC count: Can suggest infection, inflammation or a stress response; rarely a blood disorder.
- Low WBC count: Can follow viral infections or certain medicines.
- Low platelets: Seen in dengue and some other infections, and with certain medicines.
A single out-of-range value is common and often not serious. Discuss your report with a doctor.
Who should get this test?
- Everyone, yearly, as part of a routine health checkup.
- Anyone with symptoms such as persistent tiredness, breathlessness, frequent infections, fever lasting more than a few days, or easy bruising.
- Women of reproductive age, who have a higher risk of iron-deficiency anaemia.
- Preparation: No fasting needed. Tell your doctor about any medicines you take.
This page is for general information and is not a substitute for medical advice. Always interpret your results with a qualified doctor.