The complete blood count (CBC) is the most common blood test there is. It groups several values together, and each group has its own job. Let’s go through them in plain language: what they mean and what to pay attention to.
| Category | Reference range |
|---|---|
| Hemoglobin (women / men) | 120–150 / 130–170 g/L |
| Red blood cells (women / men) | 3.8–4.5 / 4.0–5.1 ×10¹²/L |
| White blood cells | 4.0–9.0 ×10⁹/L |
| Platelets | 150–400 ×10⁹/L |
| ESR (women / men) | up to 20 / up to 15 mm/h |
These ranges are approximate and depend on the lab, the method used, sex and age. Always compare your numbers with the reference values printed on your own report.
A CBC shows what your blood is made of: how many cells of each type it contains. Think of it as a census of your blood — it lets a doctor see whether there are signs of anemia, inflammation, infection or a clotting problem.
Blood has three main types of cells, and a CBC measures each of them: red blood cells (they carry oxygen), white blood cells (immune defense) and platelets (clotting). ESR is counted separately — it is an indirect marker of inflammation.
Hemoglobin is the protein inside red blood cells that delivers oxygen around the body. When these values drop, it can mean anemia — hence the tiredness, pale skin and shortness of breath. The most common cause is iron deficiency.
Extra indices (MCV, MCH) hint at the type of anemia: with iron deficiency the cells become small (microcytic), while a lack of B12 or folate makes them large.
White blood cells are the immune system’s soldiers. A rise in their number (leukocytosis) usually points to inflammation or infection, but it also happens after exercise, stress and meals. A drop (leukopenia) is less common and needs a doctor’s attention.
The differential — the balance between the various types of white cells — matters too: it often suggests whether the cause is viral or bacterial.
Platelets are responsible for clotting, that is, for stopping bleeding. Any deviation is read together with how you feel and with the other values.
ESR (erythrocyte sedimentation rate) is a non-specific “inflammation sensor”: on its own it diagnoses nothing, but alongside the white cell count it helps complete the picture. A mild rise is common after a cold.
Read each value next to the reference range printed on your report and, most importantly, look at the results as a whole rather than one by one. A CBC is a snapshot of a single moment — how the numbers change over time matters as well.
Small deviations are often harmless and simply reflect a recent illness, physical exertion or dehydration. But changes that persist or are pronounced are a reason to show the result to a doctor rather than to diagnose yourself.
No need to decode the numbers yourself: take a photo of the report and the app explains “Complete blood count” and the rest in plain words — what is normal and what deserves attention.
Get the appOpen in TelegramWhat your blood is made of: red blood cells and hemoglobin (oxygen transport), white blood cells (immunity), platelets (clotting) and ESR (an indirect marker of inflammation). It is used to spot anemia, inflammation and infections, and to get a sense of your general condition.
You are often asked to come in the morning on an empty stomach, but the rules for a CBC are usually less strict than for a biochemistry panel. Check the exact requirements with your lab.
Not necessarily. Small deviations happen after an illness, physical exertion or dehydration. Values are assessed together and over time, and it is your doctor who draws the conclusion.
This material is for general information only. It is not a medical opinion and does not replace a consultation with a doctor. Reference ranges depend on the laboratory and the method — rely on the range printed on your own report. Your doctor makes the final interpretation. This page is a translation of the Russian original. The medical review applies to the original text.
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