What Does a Full Blood Count (FBC) Actually Tell You?
Author: Tharb Faisl
It’s One of the Most Common Blood Tests — But What Does It Actually Measure?
Whether you’re feeling under the weather or just going for a general health check, there’s a good chance your doctor will request a Full Blood Count test — also called an FBC test.
At Marylebone Diagnostic Centre, we provide fast, private Complete Blood Count tests in London, with same-day appointments and clear explanations — no GP referral needed.
What Is a Full Blood Count?
A Full Blood Count test / Complete Blood Count measures the levels and characteristics of different blood cells in your body. It offers crucial insight into:
- Oxygen delivery (via red blood cells)
- Immune system activity (via white blood cells)
- Clotting function (via platelets)
It’s a broad test used to detect early signs of illness — including anaemia, infections, immune disorders, or inflammation.
What’s Included in a Full Blood Count Test?
| Marker | What It Means |
|---|---|
| Haemoglobin (Hb) | Oxygen-carrying protein — low levels may indicate anaemia |
| Haematocrit (Hct) | Proportion of blood made of red cells |
| Red Cell Count (RBC) | Total number of red blood cells |
| MCV, MCH, MCHC | Size & haemoglobin content — helps identify anaemia type |
| White Cell Count (WBC) | High in infection/inflammation; low if immune system suppressed |
| Neutrophils, Lymphocytes, etc. | Specific white cells — hint at infection, allergy, or immune response |
| Platelets | Crucial for clotting — abnormal levels may affect bleeding risk |
Why Might You Need a Full Blood Count Test?
You might need a Complete Blood Count test if you’re experiencing:
- Persistent tiredness or weakness
- Frequent infections or viruses
- Unexplained bruising or bleeding
- Symptoms of anaemia or low iron
- Long-term fatigue or immune concerns
- A routine health screen or wellness MOT
A Full Blood Count test is often the first step in identifying deeper issues — guiding further testing or treatment.
Why Choose Marylebone Diagnostic Centre?
Same-day blood testing in Central London
Calm, discreet clinic near Paddington
Rapid results in 24–48 hours
Clear explanations with every result
Adheres to the Marylebone High Standard for care & accuracy
You can also combine your Complete Blood Count test with:
- Iron studies
- Vitamin B12 and folate
- Thyroid panel
- Vitamin D and CRP for inflammation
Common Questions About the FBC Test
Q: Do I need to fast for a Full Blood Count test?
A: No — it’s a non-fasting blood test that can be done anytime.
Q: Can a Complete Blood Count test detect cancer?
A: Not directly, but abnormal results may prompt further testing.
Q: How often should I have an FBC test?
A: Once a year for general health, or more frequently if you have symptoms.
Book Your Complete Blood Count Test in London
Don’t wait for symptoms to worsen. A private Full Blood Count test can give you peace of mind — or the answers you need to take action.
📍 Book now at marylebonediagnosticcentre.com
📞 Or call our team to speak with a friendly medical advisor.
One test. Clear answers. Peace of mind.
Your blood tells a story. Let’s help you read it.