🧪 Men's Health

Full Blood Count (FBC): What Your Results Mean

Decoding your blood count results in plain English

The full blood count (FBC): also called a complete blood count (CBC), is the most commonly ordered blood test in medicine. It measures the number and type of cells in your blood: red cells (which carry oxygen), white cells (which fight infection), and platelets (which help with clotting). A single FBC gives your doctor information about anaemia, infection, bone marrow function, bleeding disorders, and much more. This guide explains every component of your FBC result and what values outside the normal range might mean.

Signs and Symptoms

✓ FBC is ordered for: fatigue, pallor, recurrent infections, unexplained bruising or bleeding, monitoring chronic illness, pre-operative assessment, routine health check
✓ The test itself requires a small blood sample drawn from a vein, results typically available within 1–4 hours
✓ Normal ranges can vary slightly between laboratories, always interpret results in context of symptoms

Risk Factors

  • Red cell parameters: Hb, RBC count, haematocrit (HCT), MCV, MCH, MCHC, RDW
  • White cell parameters: total WBC, differential (neutrophils, lymphocytes, monocytes, eosinophils, basophils)
  • Platelet parameters: platelet count, MPV
  • Always look at trends: a single result is less informative than how values change over time

When to Seek Help

Haemoglobin (Hb) critically low < 7 g/dLSevere anaemia: risk of heart failure. May need urgent transfusion
White blood cells (WBC) > 30 × 10⁹/L or < 1.5 × 10⁹/LSevere infection, leukaemia, or bone marrow failure, urgent haematology review
Platelets < 20 × 10⁹/LVery high bleeding risk: spontaneous bleeding possible. Urgent review needed
Neutrophils < 0.5 × 10⁹/L (neutropaenia)Severely immunosuppressed: risk of overwhelming bacterial infection. Often from chemotherapy or medication
Any result flagged as 'critical' by the laboratoryCall your doctor the same day: do not wait for a scheduled follow-up

Tests & Diagnosis

🧪 Haemoglobin (Hb)
Normal: men 13–17 g/dL, women 12–15 g/dL. Below normal = anaemia. Causes: iron deficiency, malaria, sickle cell, blood loss, chronic disease, B12/folate deficiency
🧪 MCV (Mean Corpuscular Volume: red cell size)
Normal 80–100 fL. Low (microcytic) = iron deficiency, thalassaemia. High (macrocytic) = B12/folate deficiency, liver disease, alcohol, some drugs. Normal (normocytic) = acute blood loss, anaemia of chronic disease, haemolysis
🧪 White blood cells (WBC)
Normal 4–11 × 10⁹/L. High (leucocytosis) = infection (bacterial), inflammation, steroids, leukaemia, stress response. Low (leucopaenia) = viral infection, HIV, autoimmune, chemotherapy, B12/folate deficiency
🧪 Neutrophils
60–70% of WBCs. First responders to bacterial infection. Elevated in bacterial infection, inflammation, steroids. Reduced in viral illness, some medications, bone marrow problems
🧪 Lymphocytes
20–40% of WBCs. Key players in viral immunity. Elevated in viral infection (EBV, CMV), lymphoma, CLL. Reduced in HIV, immunosuppressants, steroids
🧪 Eosinophils
Normal < 0.5 × 10⁹/L. Elevated in parasitic infection (roundworm, hookworm, strongyloides), allergic conditions (asthma, eczema), drug reactions. High eosinophils in Nigeria almost always means helminths or allergy
🧪 Platelets
Normal 150–400 × 10⁹/L. Low (thrombocytopaenia) = malaria, dengue, ITP, liver disease, DIC, HIV, drugs. High (thrombocytosis) = infection, inflammation, iron deficiency, after splenectomy
🧪 RDW (Red cell Distribution Width)
Measures variation in red cell size. Elevated in mixed deficiency anaemia, iron deficiency, B12 deficiency, helps distinguish types of anaemia

Treatment Options

1
Anaemia (low Hb)
Treatment depends on cause: not automatically iron tablets. Confirm cause first with MCV, ferritin, blood film
2
Infection (raised WBC + neutrophils)
Clinical assessment + C-reactive protein (CRP) + relevant cultures. Antibiotics only if bacterial infection confirmed
3
Eosinophilia
Stool microscopy for ova and parasites. Deworming with albendazole or mebendazole if helminths found
4
Thrombocytopaenia (low platelets)
Rule out malaria first in Nigeria. Further investigation if malaria excluded: FBC repeat, blood film, immunology
5
Abnormal white cell differential
Haematology review if blast cells (leukaemia), very high lymphocytes (CLL), or persistently abnormal pattern

Frequently Asked Questions

My WBC is slightly elevated: do I have leukaemia?
Almost certainly not. The vast majority of elevated WBC results reflect infection, inflammation, or steroid use, not leukaemia. Leukaemia causes very high WBC (often > 30–50 × 10⁹/L) and is usually accompanied by abnormal cells visible on the blood film. A mildly elevated WBC in a person with fever almost always means bacterial infection.
My Hb is 10 g/dL: do I need a transfusion?
Not necessarily. Haemoglobin of 10 g/dL is mild-moderate anaemia. Transfusion is generally reserved for Hb < 7–8 g/dL (or higher if symptoms are severe or there is cardiac disease). The appropriate response at 10 g/dL is to identify and treat the cause, iron deficiency, malaria, etc.
What is a blood film and when is it ordered?
A peripheral blood film involves a trained scientist examining blood cells under a microscope, looking for malaria parasites, sickle cells, abnormal white cells, platelet clumping, and many other findings. It is ordered when the automated FBC cannot explain abnormal results.
How often should I check my FBC?
Healthy adults do not need routine FBC without symptoms. People on medications that affect bone marrow (methotrexate, hydroxyurea, carbimazole), those with chronic conditions (sickle cell, HIV, kidney disease), or those being monitored for anaemia need regular FBC monitoring as directed by their doctor.

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Last updated 16 October 2026.