Meaning of Full Blood Count Test
A full blood test (FBC) shows the health of your red blood cells, white blood cells, platelets, and overall immune and oxygen-carrying function. It’s one of the most commonly ordered tests because it gives a quick snapshot of your general health.
What Is a Full Blood Test?
A full blood test, or FBC, measures the main components of your blood: red cells, white cells, and platelets. Doctors use it to check for infections, anaemia, inflammation, immune problems, bleeding disorders, and general health concerns.
It’s often included in routine check-ups because it helps detect issues early—sometimes before symptoms appear.
FBC vs. “Full Blood Work”
A FBC is one part of full blood work. Full blood work may include additional panels like kidney, liver, thyroid, cholesterol, vitamins, and hormones.
What Does a Full Blood Test Show? (Detailed Breakdown)
Here’s what each component reveals about your health:
1. Red Blood Cells (RBC) — Energy & Oxygen Levels
RBCs carry oxygen throughout the body.
A CBC shows if you have too few (anaemia) or too many (often dehydration or smoking-related).
Low RBC levels may cause:
- Fatigue
- Dizziness
- Pale skin
- Shortness of breath
High RBC levels may indicate dehydration or certain chronic conditions.
2. Haemoglobin & Haematocrit — Oxygen-Carrying Ability
These two markers show how effectively your blood can carry oxygen.
Low haemoglobin or haematocrit typically points to:
- iron deficiency
- B12 or folate deficiency
- blood loss
- chronic illness
Very high levels are less common but may indicate dehydration or bone marrow issues.
3. White Blood Cells (WBC) — Immune System Health
WBC counts show how your body responds to infection, inflammation, or immune disorders.
High WBC levels may indicate:
- Bacterial infection
- Inflammation
- Stress
- Allergic reactions
Low WBC levels may signal:
- Viral infections
- Autoimmune disorders
- Bone marrow problems
- Medication side effects
4. Platelets — Blood Clotting Ability
Platelets help stop bleeding. Low platelets (thrombocytopenia) may cause:
- Easy bruising
- Nosebleeds
- Prolonged bleeding
High platelets (thrombocytosis) may be linked to inflammation or bone marrow disorders.
5. Differential Count — Types of White Blood Cells
A differential count breaks down WBCs into neutrophils, lymphocytes, monocytes, eosinophils, and basophils.
This helps identify:
- Bacterial infection (high neutrophils)
- Viral infection (high lymphocytes)
- Allergies or asthma (high eosinophils)
- Inflammation or autoimmune issues
What Can a Full Blood Test Detect
A FBC can help detect or indicate:
- Iron deficiency anaemia
- B12 or folate deficiency
- Infections (viral or bacterial)
- Inflammation
- Immune dysfunction
- Blood loss
- Bleeding disorders
- Dehydration
- Allergic reactions
- Certain chronic conditions
Does a Full Blood Test Show Vitamin Levels?
Short answer: No, a FBC does not directly measure vitamins.
However, it can show signs associated with deficiencies.
For example:
- Low haemoglobin → possible iron or B12 deficiency
- Large red blood cells → possible folate or B12 deficiency
To measure nutrients directly, doctors order separate tests like:
- Vitamin B12
- Folate
- Vitamin D
- Iron studies
Does a Full Blood Test Show Liver, Kidney, or Thyroid Problems?
A FBC alone does not assess liver, kidney, or thyroid function.
These require separate panels:
- Liver Function Test (LFT) — enzymes, bilirubin, protein levels
- Kidney Function Test (U&E / CMP) — creatinine, electrolytes
- Thyroid Function Test (TFT) — TSH, T3, T4
Your doctor may order them together depending on symptoms.
When Should You Get a Full Blood Test
Doctors may recommend a full blood test if you experience:
- Persistent fatigue or low energy
- Frequent infections
- Dizziness or fainting
- Unexplained bruising
- Pale skin
- Heavy periods
- Chronic inflammation
- Weight changes
- Ongoing symptoms without a clear cause
It’s also used for routine health assessments and before starting certain medications.
Can You Get a Full Blood Test Through Telehealth?
Yes. A doctor can assess your symptoms via telehealth and issue a digital pathology referral.
You then visit a pathology collection centre to have the blood drawn.
You can book a telehealth appointment with Instant Consult and talk to one of our Australian-registered doctors within 15 minutes to get your online pathology referral. An online referral is accepted to any pathology centre across Australia.
