What this test measures
A Complete Blood Count (CBC) is the single most-ordered blood test in clinical practice. It reports the number, size and concentration of the three main blood cell types — red blood cells, white blood cells and platelets — along with haemoglobin (the oxygen-carrying protein) and a haematocrit (the fraction of blood made up of red cells).
A standard Indian CBC report includes about a dozen measurements: haemoglobin, RBC count, total leucocyte count (TLC / WBC), platelet count, haematocrit (PCV), mean cell volume (MCV), mean cell haemoglobin (MCH), mean cell haemoglobin concentration (MCHC), red cell distribution width (RDW), and a differential count of the five WBC subtypes (neutrophils, lymphocytes, monocytes, eosinophils, basophils).
Why it matters
A CBC is the first test most doctors order when something seems off — fatigue, fever, unexplained bruising, before any surgery, during pregnancy, or as a routine annual screen. It picks up anemia (low haemoglobin or RBCs — extremely common in Indian adults, especially women), infection (high or shifted WBC count), bleeding disorders (low platelets), and red flags for serious illness like leukemia or aplastic anemia.
Because it costs little and reports within hours, the CBC is also used to monitor people already on treatment: anticoagulants, chemotherapy, immunosuppressants, or iron / B12 / folate supplementation. Even a normal CBC is informative — it rules out a wide range of acute and chronic problems in a single tube.
How to prepare
No fasting required. You can eat and drink normally before a CBC. Heavy exercise or significant dehydration in the hours before the test can shift cell counts slightly — note these to your doctor if relevant. If you are on any medication (especially anticoagulants, chemotherapy, or immunosuppressants) keep your usual dose unless your doctor says otherwise.
Markers & reference ranges
Reference ranges below are typical adult values. Your lab's reported range may differ slightly based on the assay platform and patient demographics — always read your report against the range printed on it.
| Marker | Normal range | If low | If high |
|---|---|---|---|
| Haemoglobin (Hb) (g/dL)[1][2] | Men 13.5–17.5 · Women 12.0–15.5 · Pregnancy ≥11.0 | Low haemoglobin = anemia. Causes include iron deficiency (the most common in India), B12 / folate deficiency, chronic disease, recent bleeding, haemolysis, or haemoglobinopathies (thalassemia, sickle cell). Symptoms: fatigue, pallor, breathlessness on exertion. | High haemoglobin can reflect dehydration, smoking, living at high altitude, chronic lung or heart disease, or rarely a primary blood disorder (polycythaemia vera). Confirm with a repeat in proper hydration before working up further. |
| Total Leucocyte Count (TLC / WBC) (×10⁹/L (or cells/µL))[1] | 4.0–11.0 (4,000–11,000/µL) | Leucopenia. Viral infections, bone marrow suppression (chemotherapy, drugs), autoimmune disease, severe sepsis, B12 / folate deficiency, or hypersplenism. Very low neutrophils (<1.5) raises infection risk significantly. | Leucocytosis. Most often a bacterial infection or inflammation; also seen with steroid use, post-surgical states, severe stress, smoking, or leukemia. The differential count tells you which subtype is driving the rise. |
| Platelet Count (×10⁹/L (or cells/µL))[1] | 150–450 (1.5–4.5 lakh/µL) | Thrombocytopenia. Important causes in India: dengue, viral fevers, ITP (immune destruction), liver disease with hypersplenism, severe sepsis, B12 deficiency, and certain medications. Below 50,000 = bleeding risk; below 20,000 = spontaneous bleeding risk. | Thrombocytosis. Reactive (after infection, blood loss, iron deficiency, inflammation) — usually self-limiting. Primary (essential thrombocythaemia or other myeloproliferative disorders) — needs haematology workup, especially if persistent above 600,000. |
| MCV (Mean Cell Volume) (fL)[1] | 80–100 | Microcytic anemia. Almost always iron deficiency or thalassemia trait in Indian adults. Iron studies + haemoglobin electrophoresis (HPLC) are the standard follow-up. | Macrocytic anemia. Vitamin B12 or folate deficiency, hypothyroidism, alcohol use, liver disease, or myelodysplasia. Check B12, folate and TSH next. |
| Neutrophils (Absolute count) (%) | 40–75% (Abs 2.0–7.0 ×10⁹/L) | Neutropenia. Risk of bacterial / fungal infection rises sharply when absolute neutrophil count drops below 1.5; <0.5 is severe neutropenia (febrile-neutropenia precautions). | Neutrophilia. Bacterial infection, acute inflammation, tissue injury, post-operative, severe stress, steroid therapy. |
| Lymphocytes (Absolute count) (%) | 20–40% (Abs 1.0–3.5 ×10⁹/L) | Lymphopenia. Viral infections (including HIV in advanced stages), steroids, immunosuppression, sepsis, malnutrition. | Lymphocytosis. Viral infections (EBV, CMV, viral hepatitis, COVID-19), TB, pertussis, and chronic lymphocytic leukemia in older adults. |
How to read your haemoglobin (anemia severity, WHO 2024)
| Group | No anemia | Mild | Moderate | Severe |
|---|---|---|---|---|
| Non-pregnant women | ≥ 12.0 g/dL | 11.0–11.9 | 8.0–10.9 | < 8.0 |
| Pregnant women | ≥ 11.0 g/dL | 10.0–10.9 | 7.0–9.9 | < 7.0 |
| Men (15+ yrs) | ≥ 13.0 g/dL | 11.0–12.9 | 8.0–10.9 | < 8.0 |
| Children 5–11 yrs | ≥ 11.5 g/dL | 11.0–11.4 | 8.0–10.9 | < 8.0 |
| Children 12–14 yrs | ≥ 12.0 g/dL | 11.0–11.9 | 8.0–10.9 | < 8.0 |
Frequently asked questions
Do I need to fast for a CBC test?
No. A CBC does not require fasting and can be done at any time of day. (If it is being ordered alongside a fasting glucose or lipid profile, follow the fasting instructions for those tests.)
How long does the CBC report take?
Most NABL-accredited labs deliver CBC reports within 4–6 hours of sample collection. If the lab flags a critical value (very low haemoglobin, very low platelets), they typically alert the ordering doctor immediately.
What is the difference between a CBC and a Hemogram?
In Indian labs the two terms are used interchangeably. A "Hemogram" usually includes the same parameters as a CBC plus a differential WBC count and sometimes an ESR. The CBC alone often already includes the differential.
What do I do if my haemoglobin is low?
Low haemoglobin should be evaluated by a doctor — the cause matters more than the number. Iron studies (Iron, TIBC, ferritin) and vitamin B12 / folate are the usual next tests, and treatment depends on what is found. Self-treating with iron tablets without a diagnosis can mask the underlying problem.
My platelets are 1.2 lakh — is that dangerous?
A platelet count of 1.2 lakh (120 ×10⁹/L) is below the reference range but is usually not dangerous in isolation. Mild thrombocytopenia is common after viral fever or dengue. Repeat in a week, and consult a doctor sooner if you have any unusual bruising, gum bleeding, or rashes.
Can I do a CBC at home?
Yes — Zelnoo arranges free home phlebotomy across Mumbai and Thane. A trained phlebotomist collects the EDTA-tube sample at your address, and the report is digital within hours.
How often should a healthy adult get a CBC?
Once a year as part of a routine health check is reasonable for most adults. Pregnant women, people on long-term medication, and anyone with chronic disease may need it more often — your doctor will tell you the right interval.
Does a CBC detect cancer?
A CBC can pick up red flags for blood cancers (very high WBC, blast cells, severe pancytopenia) but it does not screen for solid tumours. Persistent unexplained abnormalities should be evaluated with a peripheral smear and haematology consult.
Related Hematology / Anemia tests
Tests commonly ordered alongside CBC, or that help interpret an unexpected result.
Sources & references
- NIH MedlinePlus — Complete Blood Count (CBC) · accessed 2026-05-29T00:00:00.000Z
- WHO — Haemoglobin concentrations for the diagnosis of anaemia · accessed 2026-05-29T00:00:00.000Z
- American Society of Hematology — Blood Basics · accessed 2026-05-29T00:00:00.000Z
- NCBI StatPearls — Complete Blood Count · accessed 2026-05-29T00:00:00.000Z
Book with Zelnoo
Get your CBC test done at home — transparent prices, NABL-accredited labs.
Zelnoo lets you compare diagnostic test prices across NABL-accredited labs in Mumbai & Thane, book a free home phlebotomist visit, and receive digital reports in 24–48 hours into a consent-first report vault. No subscriptions, no membership fees — pay only for the test you book.
Book CBC now