BiomarkersComplete blood count (CBC)

Blood & iron

Complete blood count (CBC)

A snapshot of your red cells, white cells and platelets

On your report it may say: CBC, Hemogram, Full blood count

A CBC counts and sizes your blood cells: red cells (with hemoglobin, MCV and others), white cells and platelets. It's the most common blood test, and it's a starting point, not a nutrient test.

Updated 2026-10-26

Typical ranges

Each item in a CBC has its own range. See hemoglobin and MCV for the parts most linked to nutrition.

Ranges vary by lab, age and sex. The range printed on your report applies.

If it's low

Low red cell values suggest anaemia; low white cells or platelets need a doctor's review.

Common causes

  • Anaemia from iron, B12 or folate deficiency
  • Blood loss
  • Infections or medicines (white cells)
  • Bone marrow conditions

What you might notice

  • Tiredness
  • Frequent infections
  • Easy bruising

If it's high

High counts can follow infection, dehydration or smoking, and occasionally signal blood disorders.

Common causes

  • Infection or inflammation (white cells)
  • Dehydration
  • Smoking
  • Blood disorders

What you might notice

  • Depends on which count is high

Testing

Who should test
Part of almost every health check-up.
How to prepare
No fasting needed.
When to retest
As your doctor advises.

What can help

See a doctor about any value flagged outside the lab range, especially white cells or platelets.

Common questions

Can a CBC show vitamin deficiency?

It can hint at it through red cell size, but it can't confirm which nutrient.

What is MCV?

The average size of your red cells, which helps narrow down causes of anaemia.

Explore further

Sources

  1. MedlinePlus (US National Library of Medicine): Complete blood count (CBC)

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For general education only, not medical advice. Ranges shown are typical for adults; the range printed on your lab report applies. Talk to a qualified doctor about your results.