Anaemia simply means there is not enough healthy haemoglobin — the oxygen-carrying pigment in red blood cells — to meet your body's needs. It is very common, and it is a sign rather than a diagnosis in itself. The real value of anaemia blood testing is not just confirming it, but working out what type it is and, crucially, what is causing it.
What the tests measure
A structured anaemia work-up brings together several markers:
- Haemoglobin — the headline number. If it is below the normal range, anaemia is present.
- MCV (mean cell volume) — the average size of your red cells. This is one of the most useful clues to the cause.
- Ferritin — your stored iron, the earliest marker of iron deficiency.
- Vitamin B12 and folate — both needed to make healthy red cells; a lack of either is a common cause.
Why cell size matters
The MCV helps sort anaemia into broad groups, which points towards different causes:
- Small cells (microcytic) — most often iron deficiency.
- Normal-sized cells (normocytic) — can reflect a long-term illness, blood loss or other causes.
- Large cells (macrocytic) — often linked to low B12 or folate, among other reasons.
This is why a good test does more than measure haemoglobin — the pattern across markers guides the investigation.
Symptoms to look out for
Anaemia can develop gradually, so symptoms are easy to dismiss. Common ones include persistent tiredness, breathlessness on exertion, looking pale, dizziness, headaches and, sometimes, brittle nails or unusual cravings. Mild anaemia may cause few symptoms at all, which is why it is often picked up on a routine blood count.
Check for anaemia
An anaemia profile identifies the type and likely cause of anaemia, combining a blood count with iron, B12 and folate.
Check for anaemiaWhat happens after the results
Because anaemia has so many possible causes — from dietary shortfalls to blood loss to long-term conditions — interpretation is a clinical job. A low ferritin with small red cells points one way; low B12 with large cells points another. Sometimes a cause is clear and easily addressed; other times further tests are needed to find where iron or blood is being lost. Your clinician will use the full pattern to guide the next step.
When to get checked
Consider testing if you have ongoing tiredness, breathlessness or paleness, heavy periods, a restricted diet, or you simply want to include a blood count in a general health check. If anaemia is confirmed, do not self-treat with high-dose supplements before the cause is known — the right treatment depends entirely on why it has happened, and that is best decided with a doctor.
Check for anaemia
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Specialist interest: Cardiovascular Medicine · OneMedicine, CQC-registered clinic