Haematology

Haematology tests and the blood count

Haematology is the area of laboratory diagnostics that deals with testing the blood and the blood-forming system.
Blood is one of the body’s most important “carriers of information”: its composition, its cells and their proportions give a detailed picture of your health, of how your organs work and of the processes going on in your body.

Haematology tests can detect blood disorders, infections, inflammation, anaemia, clotting disorders and many other abnormalities, so they play a basic role in almost every area of medical diagnosis.

What does haematology test?

Haematology tests analyse the blood cells (red blood cells, white blood cells, platelets) and their proportions, as well as the blood’s clotting properties and quality characteristics.

The most common haematology tests are:

1. Full blood count (CBC – Complete Blood Count)

A full blood count is the most common and most important haematology test, giving a wide range of basic information about your body.
It can determine:

• Red blood cells (RBC): responsible for supplying the body with oxygen. A low count may point to anaemia, a high count to dehydration or increased red blood cell production.
• Haemoglobin (HGB): the protein in red blood cells that carries oxygen. A low haemoglobin level is typical of anaemia (often due to iron deficiency) or blood loss.
• Haematocrit (HCT): shows the ratio between the liquid part of the blood (plasma) and its cells.
• White blood cells (WBC): the body’s defence cells. A rise in their number may indicate inflammation, infection or allergy, while a fall may point to a weakened immune system.
• Platelets (PLT): play a role in blood clotting. Low levels may point to a tendency to bleed, high levels to an increased tendency to thrombosis.

The blood count therefore gives a complex picture of the composition of your blood and helps the doctor spot disease processes in your body in time.

1. Testing for anaemia

Anaemia is the most common haematological abnormality. It develops when the body does not produce enough red blood cells or haemoglobin, or when these break down too early.

Alongside the blood count, lab tests often check:

• the iron, transferrin and ferritin levels,
• the vitamin B12 level,
• and the amount of folic acid.

These results help decide whether the anaemia is due to iron deficiency, linked to a chronic disease or caused by poor absorption.
Early detection is key here too, because anaemia can cause lasting tiredness, dizziness, paleness and poor concentration.

1. White blood cell differential (qualitative blood count)

White blood cells come in several types (neutrophils, lymphocytes, monocytes, eosinophils, basophils), each with a different job in the immune system.
The differential blood count shows their proportions in the blood, which helps to tell apart:

• a bacterial infection (raised neutrophil percentage),
• a viral infection (higher lymphocyte count),
• an allergic reaction or parasitic infection (raised eosinophils, basophils).

This test is especially important in diagnosing inflammatory and infectious diseases.

1. Platelet count and clotting tests

The platelets (thrombocytes) play a key role in stopping bleeding: they clump together to seal a damaged vessel wall and start the clotting process.
A platelet count that is too low may point to a tendency to bleed, while a value that is too high may point to a tendency to thrombosis.

There are also separate tests of blood clotting, for example:

• PT (prothrombin time) and INR (international normalised ratio)
• aPTT (activated partial thromboplastin time).
• thrombin time
• fibrinogen

They can be used to check how the clotting system works and the effect of blood-thinning medicines, which is vital for treating people with heart and blood vessel disease safely.

What are haematology tests for?

With haematology results, the doctor can:

• detect early anaemia, infections, and inflammatory or immunological abnormalities,
• assess the state of blood clotting and the immune system,
• check how effective drug or cancer treatments are,
• and prevent serious complications such as bleeding or thrombosis.

A blood count is often extremely useful even when you have no symptoms, as a simple blood test can reveal whether your body is dealing with a deficiency, inflammation or a hidden disease.

Sample collection and what happens during the test

For a haematology test, a venous blood sample is usually taken, most often on an empty stomach.
The test is quick, takes a few minutes and is almost painless.

Preparing properly for your blood test:

• For 8–12 hours before the blood test, do not eat; drink only water.
• Avoid caffeine, alcohol and smoking.
• On the day of the sample, rest and avoid strenuous physical activity, as this can affect the results.

Once the sample has been analysed in the laboratory, the doctor assesses the data together with your clinical symptoms and recommends further tests if needed.

Why haematology tests matter for staying healthy

A blood count is one of the quickest, most accurate and most comprehensive ways to assess your general health.
The laboratory results allow hidden diseases to be detected in time, making prevention and targeted treatment possible.

This is why haematology tests are strongly recommended not only for diagnosis but also as regular health check-ups – because staying healthy is always easier than treating illness.