How to Interpret Blood Test Results: The Complete Australian Biomarker Guide

A practical guide to reading and interpreting your Australian blood test results — CBC, metabolic panel, hormones, thyroid, and inflammation markers — with functional optimal ranges beyond lab normals.

This guide is for educational purposes only and does not constitute medical advice. Results should be interpreted by a qualified medical practitioner in the context of your full clinical picture.

Your pathology report says "normal" — but you feel anything but. You're exhausted, your recovery is poor, your brain fog won't lift, and every marker sits comfortably inside the reference range. How is that possible?

Learning how to interpret blood test results beyond the H and L flags on your report is one of the most useful skills you can develop as a health-optimiser. This guide explains the difference between lab reference ranges and functional optimal ranges, walks through how to read an Australian pathology report, and covers the key biomarker panels — CBC, metabolic, liver, kidney, thyroid, hormones, and inflammation — with the specific numbers that matter.

Why "Normal Range" Does Not Equal Optimal Health

This is the most important concept in all of blood test interpretation. Understanding it changes how you read every result you ever receive.

How reference ranges are established

Australian pathology laboratories establish reference ranges by measuring a large sample of the general population and taking the central 95% of results. If you fall within that band, you receive no flag. The assumption embedded in this system is that falling within the middle 95% of the population means you are healthy.

That assumption fails for several reasons:

The reference population includes sick people. The samples used to build reference ranges come from people who were tested — many of whom were tested because they were unwell. Subclinical hypothyroidism, insulin resistance, vitamin D deficiency, and anaemia are common enough in the Australian population that they are effectively baked into what labs call "normal."
Reference ranges are designed to catch pathology, not optimise performance. A TSH range of 0.4–4.0 mIU/L spans a tenfold difference in thyroid-stimulating hormone. Both extremes of that range can produce symptoms. The lab flags neither.
Ranges are wide by design. Lab ranges must cover 95% of a diverse population across a broad age span. They are statistical constructs, not clinical targets.
Ranges vary between providers. The same ferritin result can be within range at one laboratory and flagged low at another, depending on the reference population each lab used.

What functional optimal ranges represent

Functional medicine and outcomes research use tighter ranges derived from:

Studies identifying the values associated with lowest disease risk
Symptom threshold data — the levels at which people report symptoms of excess or deficiency
Performance and longevity research on populations with consistently good health outcomes

These optimal ranges are narrower and more demanding than lab reference ranges. Meeting them does not guarantee health, but chronically falling outside them — even while remaining within lab range — is clinically meaningful.

Throughout this guide, both standard Australian reference ranges and functional optimal ranges are provided where research supports them.

How to Read an Australian Pathology Report

Report format

An Australian pathology report typically shows four columns:

| Column | What it contains | |---|---| | Test name | The marker measured | | Result | Your value and units | | Reference range | The lab's reference interval | | Flag | H (high), L (low), or blank (within range) |

Some reports add an "abnormal" or "critical" flag for values that are significantly outside range and require immediate clinical attention.

Major Australian pathology providers

The major providers you will encounter on Australian reports include Sonic Healthcare (operating as Douglass Hanly Moir, Sullivan Nicolaides, Clinpath, Dorevitch, and Laverty Pathology depending on state), Australian Clinical Labs, and QML Pathology. Each uses slightly different reference ranges, different result layouts, and different software for online portals. Always note which laboratory produced your report before comparing values across providers.

Australian vs US units — why this matters

If you are researching your results online, be aware that Australian and US pathology use different units for many markers. Using US reference ranges to interpret Australian results will give you incorrect conclusions.

| Marker | Australian units | US units | |---|---|---| | Glucose | mmol/L | mg/dL (divide by 0.0555 to convert) | | Cholesterol / Triglycerides | mmol/L | mg/dL | | Haemoglobin | g/L | g/dL (multiply AU value by 0.1 to convert) | | Creatinine | µmol/L | mg/dL | | Testosterone | nmol/L | ng/dL | | Vitamin D | nmol/L | ng/mL (divide by 2.496 to convert) | | Ferritin | µg/L (= ng/mL) | ng/mL (same value) |

The rest of this guide uses Australian units throughout.

Complete Blood Count (CBC / FBC)

The full blood count is the most commonly ordered test in Australia. It assesses red blood cells, white blood cells, and platelets. For a detailed marker-by-marker breakdown with functional optimal ranges in Australian SI units, see the dedicated CBC blood test optimal ranges guide.

Red cell markers

Haemoglobin (Hb)

| | Women | Men | |---|---|---| | Lab reference | 120–160 g/L | 130–175 g/L | | Functional optimal | 130–150 g/L | 145–165 g/L |

Low-normal haemoglobin with fatigue symptoms warrants iron studies regardless of whether a flag appears.

MCV (mean corpuscular volume)

| Lab reference | Optimal | Low MCV means | High MCV means | |---|---|---|---| | 80–100 fL | 82–92 fL | Iron deficiency | B12 or folate deficiency |

MCV is one of the most useful pattern markers in the CBC. Always interpret it alongside ferritin and the iron panel, B12, and folate.

RDW (red cell distribution width)

Reference: 11.5–14.5%
Elevated RDW with normal Hb suggests early mixed nutritional deficiency — the red cells are uneven in size before anaemia develops

Haematocrit (HCT)

Reference: 0.37–0.47 (women), 0.40–0.52 (men)
Elevated haematocrit (>0.52 in men) warrants investigation — can indicate dehydration, sleep apnoea, or polycythaemia

White cell markers

Total white cell count (WBC)

| Lab reference | Functional optimal | |---|---| | 4.0–11.0 × 10⁹/L | 4.0–7.5 × 10⁹/L |

Chronically elevated WBC in the upper reference range (8–11 × 10⁹/L) without active infection may indicate low-grade systemic inflammation or metabolic stress. Research links persistently elevated WBC to increased cardiovascular and all-cause mortality risk.

Differential (neutrophils, lymphocytes, monocytes)

The differential breakdown matters more than the total WBC for most functional assessments. Low neutrophils may indicate viral suppression, B12/folate deficiency, or medication effects. Low lymphocytes are associated with overtraining and chronic stress.

Platelets

Reference: 150–400 × 10⁹/L
Functional optimal: 150–350 × 10⁹/L
Low platelets combined with elevated liver enzymes may indicate hepatic congestion

Metabolic and Biochemistry Panel

Glucose and insulin regulation

Fasting glucose

| Lab reference | Functional optimal | Pre-diabetes | |---|---|---| | 3.9–5.5 mmol/L | 4.0–5.0 mmol/L | 5.6–6.9 mmol/L |

Most Australian labs flag glucose only above 5.5 mmol/L. From a functional standpoint, fasting glucose consistently above 5.0 mmol/L — even when technically in range — warrants attention to insulin sensitivity.

HbA1c (glycated haemoglobin)

| Lab reference | Functional optimal | Monitoring zone | Pre-diabetes | |---|---|---|---| | <48 mmol/mol (<6.5%) | <37 mmol/mol (<5.4%) | 38–41 mmol/mol (5.5–5.9%) | 42–47 mmol/mol (6.0–6.4%) |

HbA1c reflects average blood glucose over approximately 12 weeks. A result in the "normal" range up to 47 mmol/mol still represents meaningful glycaemic stress at the upper end.

Fasting insulin

| Lab reference | Functional optimal | Insulin resistance concern | |---|---|---| | <25 mIU/L | <8 mIU/L | >12–15 mIU/L |

Fasting insulin is one of the most important — and most frequently omitted — markers in a standard metabolic panel. Insulin resistance appears in the insulin result years before glucose becomes abnormal. Requesting fasting insulin alongside glucose is worth the additional cost.

HOMA-IR (calculated)

HOMA-IR = (fasting insulin × fasting glucose) ÷ 22.5

Optimal: <1.5
Concern: >2.0 indicates meaningful insulin resistance even with "normal" glucose

Liver function markers

ALT (alanine aminotransferase)

| Lab reference | Functional optimal | |---|---| | <45 U/L (men), <35 U/L (women) | <30 U/L |

ALT is the primary marker of hepatocyte stress. Elevated ALT — even within the upper reference range — in the context of metabolic syndrome, high alcohol intake, or central adiposity is clinically relevant. Research suggests that ALT above 25–30 U/L corresponds with increasing hepatocyte injury even without formal "elevation."

GGT (gamma-glutamyl transferase)

| Lab reference | Functional optimal | |---|---| | <65 U/L (men), <40 U/L (women) | <20 U/L |

GGT is often the first liver function marker to rise. It is a sensitive indicator of alcohol intake, NAFLD (fatty liver), oxidative stress, and medication load. Elevated GGT within the reference range is not trivial — it should prompt a review of alcohol, carbohydrate intake, and supplement or medication use.

AST (aspartate aminotransferase)

Reference: <40 U/L
AST/ALT ratio above 2:1 suggests alcohol-related liver disease
Elevated AST with normal ALT may reflect muscle breakdown rather than hepatic stress

Albumin

Reference: 35–50 g/L
Low albumin (<38 g/L) indicates malnutrition, chronic disease, or hepatic insufficiency — a non-specific but important marker of systemic function

Kidney function markers

eGFR (estimated glomerular filtration rate)

| Lab reference | Functional optimal | Mildly reduced | CKD stage 3 | |---|---|---|---| | >60 mL/min/1.73m² | >90 mL/min/1.73m² | 60–89 | <60 |

The lab flags eGFR only when it falls below 60 — but eGFR in the 60–89 range in a younger person warrants monitoring rather than reassurance.

Creatinine

Reference: 60–110 µmol/L (men), 45–90 µmol/L (women)
Creatinine is affected by muscle mass — highly muscular individuals may show elevated creatinine without kidney disease. eGFR and cystatin C are more reliable in this context.

Urea

Reference: 2.5–8.0 mmol/L
Elevated urea with elevated creatinine = renal impairment
Elevated urea with normal creatinine = high protein intake or dehydration

Lipid Panel and Cardiovascular Markers

Triglycerides

| Lab reference | Functional optimal | |---|---| | <1.7 mmol/L | <1.0 mmol/L |

Triglycerides are the most sensitive lipid marker of insulin resistance. Fasting triglycerides above 1.0 mmol/L — even well within reference range — in the context of elevated glucose or insulin, are an early metabolic signal.

HDL cholesterol

| Lab reference | Functional optimal | |---|---| | >1.0 mmol/L (men), >1.2 mmol/L (women) | >1.4 mmol/L (men), >1.6 mmol/L (women) |

LDL cholesterol

Reference: <3.0 mmol/L general population; <2.0 mmol/L high-risk
Standard LDL is a calculated value. It underestimates atherogenic particle burden in some metabolic contexts, particularly when triglycerides are elevated
LDL particle number (LDL-P) and ApoB are more predictive than calculated LDL

ApoB (apolipoprotein B)

Reference: <1.0 g/L
Functional optimal: <0.7 g/L
Each atherogenic lipoprotein particle carries exactly one ApoB molecule. ApoB directly counts atherogenic particle burden and outperforms LDL cholesterol as a cardiovascular risk predictor.

hs-CRP (high-sensitivity C-reactive protein)

| Lab reference | Functional optimal | Low risk | Moderate risk | |---|---|---|---| | <5 mg/L | <1.0 mg/L | <1.0 | 1.0–3.0 mg/L |

Chronically elevated hs-CRP in the 1–3 mg/L range is associated with increased cardiovascular, metabolic, and cognitive risk even without active infection.

Thyroid Panel

The thyroid panel warrants its own dedicated deep-dive — see the comprehensive thyroid panel interpretation guide for full marker-by-marker analysis including reverse T3, antibody patterns, and medication-adjusted interpretation.

TSH (thyroid-stimulating hormone)

| Lab reference | Functional optimal | |---|---| | 0.4–4.0 mIU/L | 1.0–2.5 mIU/L |

TSH above 2.5 mIU/L in a symptomatic patient is worth investigating further even when it falls within the lab reference range.

Free T4 and Free T3

| Marker | Lab reference | Functional optimal | |---|---|---| | Free T4 | 10–25 pmol/L | 16–22 pmol/L | | Free T3 | 3.5–6.5 pmol/L | 5.0–6.5 pmol/L |

Low-normal Free T3 with adequate Free T4 suggests impaired conversion — associated with chronic stress, caloric restriction, and selenium deficiency.

TPO antibodies

Positive TPO antibodies (>35 IU/mL) indicate Hashimoto's thyroiditis regardless of TSH. This is the most commonly missed thyroid diagnosis in Australia — TSH can remain normal for years while autoimmune damage progresses.

Hormone Panels

Hormone interpretation is highly context-dependent and requires dedicated analysis. The following provides functional reference points only.

For women's hormone markers — including estradiol cycle timing, optimal ranges by phase, and the estradiol-SHBG interaction — see the estradiol blood test interpretation guide.

Testosterone (men)

For a full breakdown including free testosterone, SHBG, and the LH/FSH pattern, see the optimal testosterone ranges for men guide.

| Marker | Lab reference | Functional optimal | |---|---|---| | Total testosterone | 8.0–29.0 nmol/L | 18–28 nmol/L | | Free testosterone | 225–725 pmol/L | Upper third of range | | SHBG | 15–70 nmol/L | 25–45 nmol/L |

Symptoms of testosterone deficiency are common below 12–14 nmol/L, even though most Australian labs do not flag until below 8.0 nmol/L.

Vitamin D (25-OH D)

| Lab reference | Functional optimal | Deficiency | |---|---|---| | >50 nmol/L | 100–150 nmol/L | <50 nmol/L |

The Australian lab "sufficient" cutoff of 50 nmol/L is derived from bone health data only. Evidence for immune function, inflammation regulation, and cardiometabolic health points to higher targets. See the optimal vitamin D levels in Australia article for seasonal variation by state and the research behind the 100–150 nmol/L target.

Cortisol and adrenal markers

For detailed interpretation of the cortisol/DHEA axis, including the limitations of a single morning draw, see the cortisol and DHEA adrenal panel guide.

| Marker | Reference | Optimal (morning) | |---|---|---| | Cortisol (serum, 8–9 am) | 140–700 nmol/L | 400–550 nmol/L | | DHEA-S (women) | 1.0–11.5 µmol/L | Age-matched upper quartile | | DHEA-S (men) | 2.5–12.0 µmol/L | Age-matched upper quartile |

Red Flag Results That Require Prompt Follow-Up

The following results should be discussed with a medical practitioner promptly — do not wait for a scheduled review:

| Marker | Red flag threshold | Likely significance | |---|---|---| | WBC | >10 × 10⁹/L or <3 × 10⁹/L | Active infection, haematological abnormality | | Calcium (corrected) | >2.65 mmol/L | Hyperparathyroidism, malignancy | | Sodium | <130 or >150 mmol/L | Significant electrolyte disturbance | | Potassium | <3.0 or >5.5 mmol/L | Cardiac arrhythmia risk | | ALT or AST | >3× upper limit of normal | Significant hepatocyte injury | | eGFR | <60 mL/min/1.73m² | CKD stage 3 or above | | Haemoglobin | <100 g/L | Moderate-to-severe anaemia | | TSH | <0.1 or >10 mIU/L | Overt thyroid dysfunction |

These thresholds indicate that something needs clinical assessment — not necessarily that a serious diagnosis is present. Context, trend, and clinical picture all matter.

How to Track Trends Over Time

A single blood test is a snapshot taken at one moment under one set of conditions. Fasting status, sleep the night before, recent exercise, illness, stress, and hydration all affect your results.

The real signal emerges over time. Key principles for tracking:

Keep your own records. Australian pathology providers vary in how long they retain results in patient portals. Export your results as PDFs and maintain a personal spreadsheet — at minimum: date, provider, marker name, result, and reference range. A simple spreadsheet with results across 3–4 testing dates will reveal trends that a single report cannot.

Compare like with like. Where possible, use the same laboratory, the same time of day, and the same fasting status for sequential tests. Switching labs changes reference ranges and may change assay methods.

Track direction, not just thresholds. A fasting insulin moving from 6 to 9 to 14 mIU/L over two years is important even if it has not yet crossed any threshold. A vitamin D moving from 60 to 80 to 110 nmol/L during supplementation tells you your protocol is working. Direction matters.

Biannual testing is the minimum for active optimisers. Annual testing catches large changes. Six-monthly testing allows you to identify trajectories and intervene before a trend becomes a problem.

Getting Tested in Australia

Through a GP (Medicare-rebated)

Blood tests ordered by your GP for a clinical indication attract a Medicare rebate. The rebate applies to most standard markers (FBC, metabolic panel, lipids, thyroid, iron studies, vitamin D). Specialist markers — fasting insulin, ApoB, DHEA-S, Lp(a), sex hormones without a specific indication — may require private billing even with a GP referral.

For anyone running biomarker tracking as part of a structured wellness protocol — including those using peptide research monitoring protocols or other investigational compounds — GP-referred testing may not provide comprehensive enough panels without a cooperative practitioner.

Private testing without a GP referral

Several providers offer self-referral pathways in Australia. For a full comparison of providers, panels, and costs, see the guide to ordering a private blood test without a GP referral.

Key options:

| Provider | Best for | |---|---| | i-screen | Broadest national self-referral panels | | Laverty Pathology | NSW/QLD direct self-referral (Medicare pricing) | | RoidSafe | Hormone and performance monitoring | | NutriPATH | Functional panels (DUTCH, OAT, GI-MAP) |

For a full provider-by-provider comparison including pricing, turnaround times, and which panels each service carries, see the Australian private blood testing directory.

Testing frequency guidelines

| Population | Recommended frequency | |---|---| | Healthy adults, no active concerns | Annually | | Active optimisers, performance tracking | Every 6 months | | On any therapeutic protocol | Every 3 months (or per protocol) | | Managing a diagnosed condition | Per treating practitioner |

Frequently Asked Questions

What is a normal blood test result?

A "normal" blood test result means your value falls within the central 95% of the reference population used by the lab. It does not mean the result is optimal for health or performance. Many markers — fasting insulin, vitamin D, ferritin, thyroid hormones — can produce symptoms or increase long-term health risk at values the lab considers normal. Understanding optimal ranges gives you a more useful framework than normal/abnormal alone.

Can I order my own blood tests in Australia without a GP?

Yes. Several pathology providers and online platforms offer self-referral pathways. i-screen is the most comprehensive nationally. Laverty Pathology accepts self-referrals in NSW and QLD. Some panels are processed through the same laboratories as GP-referred tests. Costs are typically out of pocket, though some providers offer competitive pricing. See the full guide to ordering a private blood test without a GP referral.

How often should I get blood tests?

Annual testing is a reasonable minimum for adults with no active health concerns. Twice yearly is more appropriate for anyone actively tracking biomarkers, adjusting diet or supplementation, or on any form of therapy. More frequent testing — every 3 months — is appropriate if monitoring a specific marker that is changing or during an active protocol.

What does it mean when blood test results are out of range?

An H or L flag means the result falls outside the lab's reference range. It is a prompt for clinical attention, not a diagnosis. Out-of-range results should be interpreted in the context of your symptoms, medical history, other markers, and trend over time. Some out-of-range results require immediate follow-up (see the red flag table above). Others are mild deviations that warrant monitoring and lifestyle intervention. A practitioner review is recommended for any flagged result.

How do I find functional medicine reference ranges?

Functional reference ranges are not standardised across all practitioners or published in a single definitive source. They are derived from peer-reviewed outcomes research, clinical consensus among functional and integrative medicine practitioners, and longevity research. This guide includes functional optimal ranges for major markers based on the evidence base available as of the publication date. For marker-specific depth, use the spoke articles linked throughout this guide — including the comprehensive thyroid panel interpretation, optimal testosterone ranges for men, and optimal vitamin D levels in Australia.

Summary: A Framework for Interpreting Your Results

Reference range ≠ optimal. Use functional optimal ranges as your target, not just the absence of an H/L flag.
Australian units are different from US units. Always confirm units before comparing your results to any reference source.
Read markers in clusters. Iron status, thyroid function, and hormone panels each require multiple markers read together.
Timing affects results. Fasting status, time of day, cycle phase, and recent exercise all matter.
Trends matter more than single values. Keep your own records and track direction over 12 months or more.
Red flags need prompt attention. Know which values require urgent follow-up.
Get tested at the right frequency. Annual at minimum; six-monthly for active optimisers.

For marker-specific interpretation, use the linked spoke guides throughout this article. The rawmarkers.com reference library covers thyroid, adrenal, hormonal, and metabolic panels in dedicated depth — each written for the practitioner, biohacker, or informed health-optimiser who wants more than a reference range.