Is a Full Blood Count Worth It?
The Full Blood Count provides 27 data points from a single sample—and research shows your personal baseline matters more than population reference ranges. With 22% of Australian women iron deficient, this test catches problems most people miss.
22%
of Australian women have depleted iron stores—6 times higher than men—yet most don't know until symptoms become significant
Source: [1]
The Short Answer
Yes—it's the most fundamental blood test and an excellent health baseline. The FBC is the most commonly ordered blood test in Australia for a reason: 27 measurements from one sample that screen for anaemia, infection, inflammation, and blood disorders—often before symptoms become obvious. With iron deficiency affecting 22% of Australian women (35% of young women aged 18-39), the FBC frequently uncovers treatable conditions. Even more valuable: research shows your personal 'setpoint' for blood counts varies less than population reference ranges suggest—a drop from 145 to 125 g/L haemoglobin might be significant for you, even though both are technically 'normal'.[1][5]
What's in a Full Blood Count?
A Full Blood Count (FBC)—also known as a Complete Blood Count (CBC) in the US—measures three main types of blood cells from a single sample. Function Health describes blood testing as foundational: 'Your blood tells the story of your health'—and the FBC tells more of that story than any other single test.[3]
From one tube of blood, you get 27 individual measurements. That's more information per dollar than almost any other test in pathology.
| Risk Factor | Why It Matters |
|---|---|
| The oxygen-carrying protein in red blood cells. Low haemoglobin indicates anaemia—your blood's reduced ability to carry oxygen to tissues. This is the marker that reveals iron deficiency, B12 deficiency, or chronic disease anaemia. Normal: 135-180 g/L (men), 115-160 g/L (women). | |
| The number and characteristics of your red cells. Includes MCV (cell size), MCH (haemoglobin per cell), and MCHC (haemoglobin concentration). These help identify the type of anaemia—small cells suggest iron deficiency; large cells suggest B12/folate deficiency. This is where pattern recognition matters. | |
| Your immune system's frontline defenders. The differential count breaks this down into neutrophils, lymphocytes, monocytes, eosinophils, and basophils—each fighting different threats. High neutrophils suggest bacterial infection; high lymphocytes suggest viral infection; high eosinophils suggest allergic or parasitic reactions. | |
| Small cell fragments essential for blood clotting. Low platelets increase bleeding risk; high platelets may indicate inflammation or bone marrow issues. Normal: 150-400 × 10⁹/L. Most people never think about platelets until they're abnormal—but they're critical for wound healing and haemostasis. |
The Power of One Test
A single FBC provides 27 individual measurements—far more information than most people realise. Your GP can assess oxygen-carrying capacity, immune function, and clotting ability all from one tube of blood. It's the most information-dense test per dollar in pathology.[2]
Australia's Iron Deficiency Epidemic
The FBC is often the first test to detect iron deficiency—and the numbers in Australia are striking. This isn't a niche problem; it's affecting millions of women right now:
22%
of Australian women have depleted iron stores (serum ferritin <30 μg/L)—6 times higher than men[1]
35%
of young women aged 18-39 have serum ferritin <30 μg/L—the highest risk group[1]
50%
of women with heavy menstrual bleeding have iron deficiency—yet most don't realise the connection[1]
These aren't theoretical numbers. They represent real women experiencing fatigue, brain fog, breathlessness on exertion, cold intolerance, hair loss, and brittle nails—symptoms often dismissed as 'just stress' or 'part of being busy.'
The FBC can detect anaemia, but ferritin (iron stores) may be low even before haemoglobin drops. If you have heavy periods and fatigue, consider requesting iron studies alongside your FBC.[1]
Why This Matters for Women
Iron deficiency is the most common nutritional deficiency worldwide—but it disproportionately affects women of reproductive age. Heavy menstrual bleeding is the primary driver, but dietary inadequacy (particularly vegetarian/vegan diets without supplementation) and malabsorption (coeliac disease, IBD) also contribute.
The insidious part: iron deficiency develops slowly. Your body adapts gradually, so you don't notice the progressive decline in energy, exercise tolerance, and cognitive function. Many women only realise how exhausted they were once iron stores are repleted and they feel genuinely energised again.
Testing provides objective data when symptoms are vague and easy to dismiss.
Why Your Personal Setpoint Matters More Than You Think
Here's something most people—and many GPs—don't fully appreciate: research shows that healthy individuals have their own stable 'setpoint' for blood counts that varies less than population reference ranges suggest.
A landmark study from the University of Washington tracking healthy individuals over time found that a result within the 'normal range' might actually represent a significant change from your personal baseline.[5]
Population Reference Range Approach
Personal Setpoint Approach
The Empowerment of Knowing Your Baseline
This is why testing while healthy is genuinely valuable—not just for screening, but for establishing your personal reference range. Changes from your baseline matter more than absolute values compared to population norms.
A haemoglobin of 125 g/L means something different for a woman whose stable baseline is 145 versus a woman whose stable baseline is 125. The lab report shows both as 'normal,' but only one represents a change requiring investigation.
Your body knows its own setpoint. Testing gives you the data to recognise when you've deviated from it—even when the lab says everything is 'fine.'
What Each Component Reveals
The FBC doesn't just count cells—it reveals patterns that point towards specific conditions. This is where clinical interpretation matters:
Red Cell Abnormalities
- Iron deficiency anaemia (low Hb, low MCV)—affects 22% of Australian women
- B12/folate deficiency (low Hb, high MCV)
- Chronic disease anaemia (inflammatory conditions suppressing red cell production)
- Thalassaemia traits (genetic haemoglobin disorders)
- Polycythaemia (too many red cells—dehydration, lung disease, or bone marrow disorder)
White Cell Changes
- Bacterial infection (high neutrophils)
- Viral infection (high lymphocytes)
- Allergic reactions or parasitic infections (high eosinophils)
- Immune suppression (low WBC—medications, bone marrow issues)
- Leukaemia (very high or abnormal WBC patterns—rare but the FBC catches it)
Platelet Issues
- Thrombocytopenia (low platelets, increased bleeding risk)
- Thrombocytosis (high platelets, may indicate inflammation or clotting risk)
- Bone marrow disorders (abnormal production)
- Autoimmune conditions (immune destruction of platelets)
- Medication side effects (many drugs affect platelet count)
Who Should Consider Testing?
The FBC isn't recommended for routine screening in completely healthy asymptomatic people with no risk factors. But if you have symptoms, risk factors, or want to establish your personal baseline, this test provides genuine value.[2]
✗ Probably Skip If...
- You're healthy with no symptoms and had a normal FBC in the last 1-2 years
- You're just curious without specific concerns or risk factors
- You had a recent FBC for another reason (pre-operative assessment, pregnancy, routine check-up)
✓ Worth Considering If...
- Persistent fatigue or weakness not explained by lifestyle factors (sleep, stress, activity level)
- Heavy menstrual periods—50% of women with heavy bleeding have iron deficiency[1]
- Vegetarian/vegan diet without regular B12 and iron supplementation
- Frequent infections or unusually slow wound healing (suggests immune dysfunction)
- Unexplained bruising, bleeding gums, or prolonged bleeding from minor cuts
- Shortness of breath or dizziness on exertion disproportionate to fitness level
- Pale skin, brittle nails, hair loss, or cold intolerance (classic iron deficiency symptoms)
- Establishing your personal baseline while healthy—so changes are detectable early
- Pre-operative assessment, monitoring chronic conditions, or medication side effect screening
FBC: The Foundation Test
Think of the FBC as a health 'dashboard'—it won't diagnose everything, but it quickly flags when something needs investigation. This is why GPs order it so frequently: it's a remarkably efficient screening tool.
Why GPs Love the FBC
- Broad screening power: Catches anaemia, infection, inflammation, and blood disorders in one test—more conditions per sample than almost any other pathology test
- Cost-effective: 27 data points from a single sample—one of the most information-dense tests per dollar in medicine
- Gateway test: Points towards more specific testing if abnormalities found (iron studies, B12, haematology referral, bone marrow biopsy if needed)
- Establishes personal baseline: Your stable setpoint can be tracked over time—changes matter more than absolute values compared to population ranges
- Universally understood: Every GP knows how to interpret and act on FBC results—there's no ambiguity about next steps
- Quick turnaround: Results typically available within 24-48 hours—faster than most other pathology tests
- No fasting required: You can eat and drink normally before the test—no preparation needed
What Your GP Does with Results
The FBC has well-established follow-up pathways. Your GP will interpret results in context of your symptoms, history, and risk factors. Here's what typically happens when abnormalities are detected:
Follow-Up Pathways
- Low haemoglobin + low MCV (small cells): Iron studies to confirm iron deficiency; investigate cause (dietary inadequacy, malabsorption, blood loss—particularly GI bleeding or heavy menstrual bleeding). Ferritin <30 μg/L confirms depleted iron stores.[1]
- Low haemoglobin + high MCV (large cells): B12 and folate levels; if deficient, investigate cause (dietary inadequacy for B12, pernicious anaemia, malabsorption). May require lifelong supplementation or injections.
- High white cells: Repeat test to confirm; if persistent, investigate cause (infection, inflammation, smoking, rarely leukaemia). Pattern of differential count guides investigation.
- Low white cells: Assess for immune suppression (medications, viral infection, bone marrow issues). May require haematology referral if severe or unexplained.
- Low platelets: Repeat test to confirm (platelets clump easily, causing spurious low results). If confirmed, investigate cause (immune thrombocytopenia, medication effect, bone marrow disorder).
- Multiple abnormalities: May warrant urgent haematology referral—particularly if pancytopenia (low red cells, white cells, and platelets) suggesting bone marrow pathology.
Good News: Clear Action Pathways
FBC is one of the most straightforward tests for GPs to interpret, with well-established investigation and treatment pathways:[2]
- Results are actionable: Abnormalities have clear next steps—additional blood tests, imaging, specialist referral, or treatment initiation
- Medicare rebate: Covered when ordered by GP with clinical indication (symptoms, risk factors, or monitoring chronic conditions)
- Quick turnaround: Results typically available within 24-48 hours—you're not waiting weeks for answers
- No fasting required: You can eat and drink normally before the test—unlike glucose or lipid tests
- Well-researched interventions: When deficiencies or abnormalities are found, treatment efficacy is well-established (iron supplementation, B12 injections, etc.)
Is It Worth the Cost?
For a test that provides 27 data points about your blood health for around $30-40 (self-funded) or covered by Medicare when clinically indicated, the FBC offers exceptional value.
It's often the first test GPs order because it efficiently screens for multiple conditions simultaneously—from iron deficiency (affecting 22% of Australian women) to serious blood disorders, infections, and inflammatory conditions.
But the real value isn't just screening—it's establishing your personal baseline. Research shows your individual setpoint for blood counts matters more than population reference ranges. A result technically within the 'normal' range might represent a significant change from your personal baseline—and that change is clinically meaningful.[5]
The Bottom Line
The Full Blood Count is the workhorse of pathology testing—and with good reason.
With 27 measurements from a single blood sample, it's hard to find a more efficient screening test. Given that 22% of Australian women have depleted iron stores (35% of young women aged 18-39)—and many don't know it—the FBC is particularly valuable for detecting anaemia and other blood abnormalities before symptoms become severe.
What makes the FBC genuinely valuable:
- Catches problems early: Iron deficiency, B12 deficiency, infections, inflammatory conditions, and blood disorders—often before symptoms are obvious or severe
- Establishes your baseline: Research shows individual setpoints vary less than population reference ranges—knowing your personal baseline lets you detect meaningful changes even when results are technically 'normal'[5]
- Clear follow-up pathways: Abnormalities have well-established investigation and treatment protocols—your GP knows exactly what to do with results
- Cost-effective screening: 27 data points for $30-40 self-funded, or Medicare-covered when clinically indicated—exceptional information density per dollar
Who benefits most from FBC testing:
- Women with heavy menstrual periods (50% have iron deficiency)[1]
- Vegetarians/vegans (higher risk of iron and B12 deficiency)
- People with persistent fatigue, frequent infections, unexplained bruising, or breathlessness on exertion
- Anyone establishing a proactive health baseline while asymptomatic—changes from your setpoint are more clinically meaningful than population reference ranges
- Pre-operative assessment, chronic disease monitoring, or medication side effect screening
If you're experiencing fatigue, heavy periods, frequent infections, unexplained bruising, or just want to establish your personal baseline while healthy, the FBC is an excellent starting point. It won't diagnose everything, but it will quickly identify if your blood cells are functioning normally—and point your GP towards further investigation if they're not.
As a Tier 1 guideline-backed test, your GP will know exactly what to do with the results. That's the definition of good value in healthcare.
Frequently Asked Questions
Disclaimer:This information is educational only and not medical advice. Results should be interpreted by your health practitioner in the context of your symptoms and health history. Treatment decisions should be made with your doctor or specialist.