Complete Blood Count
A full blood count is a very common test. It can be used to screen for, diagnose, and monitor a variety of conditions. It can also be used as part of routine health screening. The full blood count shows the level of the different cell types in the blood (red cells, white cells and platelets). It can also show you if you have anaemia (low haemoglobin) and may show whether your body is fighting an infection (high white cells) or prone to bruising and bleeding (low platelets). A wide range of conditions can present with abnormalities in the full blood count and it can be a very useful initial test, interpretation may rely on additional tests.
Test details
What's measured in this test
Haematocrit
The proportion of red blood cells in the blood
Haemoglobin
The oxygen-carrying protein in red blood cells
Platelets
Cells which help blood to clot
Red Blood Cells
Count of Red Blood Cells (RBC), which carry oxygen
White Blood Cells (Differentiated)
Count of Basophils, Eosinophils, Lymphocytes, Monocytes and Neutrophils
White Blood Cells (Total)
Total count of White Blood Cells (WBC), which fight infection
Common reasons for testing
- General health check-up – A Complete Blood Count is a standard test in routine medical exams to ensure overall well-being.
- Unexplained fatigue or weakness – Low red blood cell counts may indicate anemia, which can cause tiredness and low energy levels.
- Signs of infection – Elevated white blood cell counts can suggest an infection, inflammation, or immune response.
- Monitoring chronic conditions – Conditions like autoimmune diseases, blood disorders, and chronic infections may require regular Complete Blood Count testing.
- Unusual bleeding or bruising – Low platelet levels can affect blood clotting and may need further investigation.
- Tracking the effects of treatments – If you’re undergoing chemotherapy, radiation therapy, or certain medications, a Complete Blood Count helps monitor blood cell health.
- Assessing nutritional deficiencies – Low hemoglobin or abnormal red blood cell levels may indicate deficiencies in iron, vitamin B12, or folate.