A pathology result marked high, low or abnormal is not automatically a diagnosis. Reference ranges describe values expected in most relevant healthy people, but healthy individuals can fall outside them and illness can exist despite an in-range result. Your symptoms, medical history, medicines, reason for testing and change over time all affect interpretation.
Start with the five parts of each result
| Report item | What it tells you | Common mistake |
|---|---|---|
| Test name | The substance, cell or process measured | Confusing similar abbreviations |
| Your result | The measured value or qualitative finding | Reading the number without the unit |
| Unit | How the measurement is expressed | Comparing values reported in different units |
| Reference interval | The laboratory’s comparison range for a relevant population | Treating its boundary as a sharp line between health and disease |
| Flag or comment | A value outside the interval or information from the laboratory | Assuming every flag has the same urgency |
What does a reference range actually mean?
A reference interval is a statistical comparison, not a guarantee. It is usually developed from results in a selected group considered healthy. A common interval captures the central 95% of that reference group, which means some healthy people will naturally sit outside it.
Ranges can depend on age, sex, pregnancy, laboratory method and other factors. The interval printed beside your result is the relevant starting point. Do not replace it with a range copied from another laboratory, overseas website or social-media post.
Why one slightly abnormal result may not mean much
Small differences can occur because of normal biological variation, hydration, recent food, exercise, stress, collection timing or the testing method. When many measurements are ordered together, the chance that at least one falls just outside its interval increases.
A clinician may decide to repeat the test under standard conditions, monitor the trend or assess related measurements before drawing a conclusion. That is not the same as ignoring the result.
Why a result can be flagged high or low
- the result genuinely reflects a health condition;
- temporary illness or inflammation affected it;
- you were dehydrated or overhydrated;
- you ate when fasting was required;
- recent strenuous exercise changed muscle or liver-related markers;
- medicine, vitamins or supplements influenced the result;
- collection time affected a hormone or medicine level;
- pregnancy, age or menstrual status changes interpretation;
- the sample was delayed, contaminated or affected during collection; or
- the value is part of your healthy individual variation.
Read the whole pattern, not one number
Many tests are interpreted in groups. A full blood count includes red cells, haemoglobin, white-cell groups and platelets. Iron studies combine several measurements. Liver and kidney panels contain related markers that provide more information together than separately.
One isolated result may be non-specific. For example, an inflammatory marker can show that inflammation exists without identifying the location or cause. A positive screening test may require a confirmatory test before a diagnosis can be considered.
Trend matters more than a single snapshot
A value that remains stable just outside its interval may be less concerning than an in-range value changing rapidly. Clinicians compare:
- your current and previous values;
- the speed and direction of change;
- whether related measurements changed together;
- whether treatment should have moved the result;
- your symptoms and physical findings; and
- whether samples were collected under comparable conditions.
Where possible, compare reports from the same laboratory because methods, units and reference intervals can differ.
Check whether the test required preparation
Before worrying about an unexpected result, check whether you followed the collection instructions.
| Factor | How it may matter | What to tell your clinician |
|---|---|---|
| Fasting | Food and drinks can affect glucose, triglycerides and selected other tests | When and what you last ate or drank |
| Hydration | Concentrated or diluted blood and urine can alter values | Vomiting, diarrhoea, heavy sweating or unusually high fluid intake |
| Exercise | Hard exercise can change muscle, liver and inflammatory markers | Type and timing of recent activity |
| Medicines and supplements | Can change the body or interfere with some assays | Every prescription, over-the-counter medicine and supplement |
| Collection timing | Hormones and monitored medicines can vary through the day or dose cycle | Collection time and last dose |
| Current illness | Infection, fever and inflammation can temporarily affect several tests | Symptoms and when they began |
Do not stop medicine before a test unless instructed
Some medicines and supplements affect pathology results, but stopping them can be dangerous. Ask the clinician or collection service what to take and when. Bring an accurate list including doses, timing, vitamins, herbal products and performance supplements.
Biotin, for example, can interfere with some laboratory tests. That does not mean everyone should stop it automatically; the appropriate action depends on the product, dose, test and clinical instructions.
Understanding common report symbols
Reports may use H for high, L for low, arrows, bold text, colour or an asterisk. Some also mark a result as critical, significantly changed or requiring clinical attention. The exact system belongs to that laboratory.
A flag usually means the value crossed a reporting threshold. It does not tell you the cause, severity or treatment. Read any comment from the pathologist and ask the ordering clinician how promptly follow-up is needed.
Common panels in plain English
Full blood count
A full blood count examines red cells, haemoglobin, white cells and platelets. Results can help investigate anaemia, infection, inflammation, bleeding and bone-marrow problems, but patterns and symptoms matter. One mildly altered cell count does not identify a diagnosis by itself.
Iron studies
Iron, ferritin, transferrin and transferrin saturation describe different aspects of iron storage and transport. Ferritin can rise with inflammation, so a single result may need interpretation alongside the full panel, blood count and clinical context.
Kidney function
Creatinine, estimated glomerular filtration rate and electrolytes help assess kidney function and fluid balance. Muscle mass, age, hydration, medicines and recent illness can influence interpretation. A trend is often important.
Liver function tests
Liver panels contain enzymes, proteins and bilirubin. They do not all measure the same thing, and an abnormal enzyme is not automatically evidence of liver failure. The pattern, degree, symptoms, medicines and alcohol history influence the next step.
Blood glucose and HbA1c
Glucose is a measurement at a particular time, while HbA1c reflects average exposure over a longer period. Fasting status matters for some glucose tests. Diagnosis and treatment decisions use recognised criteria and may require confirmation.
Cholesterol and lipids
Total cholesterol, LDL cholesterol, HDL cholesterol and triglycerides are considered with age, blood pressure, smoking, diabetes and other cardiovascular risks. A laboratory flag alone does not provide your complete risk assessment.
Thyroid tests
Thyroid-stimulating hormone is commonly interpreted with free thyroid hormones and the clinical situation. Pregnancy, acute illness, medicines and assay interference can change interpretation.
Inflammatory markers
C-reactive protein and erythrocyte sedimentation rate can indicate inflammation but are non-specific. They cannot identify the source without other information.
What “positive”, “negative” and “detected” mean
Not every pathology result is numerical. A report may say positive, negative, detected, not detected, reactive, non-reactive or indeterminate.
The meaning depends on the test. A negative result can reduce the likelihood of a condition without ruling it out completely. A positive screening result may include false positives and require confirmation. An indeterminate result may need another sample or different test.
Diagnostic accuracy depends on sensitivity, specificity and the likelihood of the condition before testing. This is why the same result can mean different things in people with different symptoms or risk.
Why units are essential
The same substance may be reported in different units. A number found online is meaningless unless the test method and unit match. Decimal placement also matters.
Never convert a value mentally when making a health decision. Use the report’s own interval and ask the clinician or laboratory if the unit appears unfamiliar.
How to use My Health Record without panicking
Most pathology reports uploaded to My Health Record are now available to view immediately, while some report types appear after a standard five-day delay. The timing is based on report type and does not indicate whether the result is good or bad.
Seeing a report before your appointment can be helpful, but it removes the clinician’s explanation. Use it to prepare questions rather than reach a diagnosis.
A five-minute pause plan
- Read the report title and collection date.
- Confirm every page belongs to the same episode.
- Note only the flagged results and laboratory comments.
- Compare with previous reports using the same units and ranges.
- Write down symptoms, medicines and preparation details.
- Book or keep the follow-up requested by your clinician.
When should you contact the doctor?
Follow the timeframe given when the tests were ordered. Contact the clinic sooner if:
- the laboratory or clinic tells you the result needs prompt review;
- the report contains a critical alert or urgent comment;
- you have significant new or worsening symptoms;
- the test monitors a medicine with potential toxicity;
- you are pregnant or immunocompromised and concerned about an abnormal result;
- several related measurements have changed substantially; or
- you do not understand the follow-up plan.
What to ask at the follow-up appointment
- Why was this test ordered?
- Is the result genuinely concerning for me?
- Could preparation, illness, medicine or supplements have affected it?
- How does it compare with my previous results?
- Do related results change the interpretation?
- Should the test be repeated, and under what conditions?
- Are further tests needed?
- Should I change medicine, diet, exercise or supplements?
- What symptoms should prompt earlier help?
- When and how will the next result be reviewed?
What not to do after reading a result
- Do not assume one flag proves a disease.
- Do not compare bare numbers without units.
- Do not use another laboratory’s range.
- Do not ignore symptoms because a test is in range.
- Do not stop prescribed treatment independently.
- Do not begin iron, potassium, vitamin D or other supplements from one number alone.
- Do not repeat tests excessively without clinical guidance.
- Do not post an identifiable report publicly.
- Do not assume a delayed My Health Record release means bad news.
How to keep useful records
Keep the original report, not only a screenshot of one value. Record the collection date, laboratory, fasting status, symptoms and relevant medicine timing. This makes later comparisons more reliable.
Protect your privacy when using health apps, email or cloud storage. Pathology reports contain identifying and sensitive information.
A practical interpretation process
- Check identity and date. Make sure the report is yours and current.
- Identify the reason for testing. Screening, diagnosis and monitoring have different purposes.
- Read the exact result, unit and interval. Keep them together.
- Read laboratory comments. They may explain limitations or recommended follow-up.
- Review preparation. Note food, hydration, exercise, illness and medicine timing.
- Compare trends carefully. Prefer the same laboratory and method.
- Consider symptoms. A number is only part of the clinical picture.
- Write questions. Avoid trying to solve the result through uncontrolled searching.
- Discuss the result. Contact the ordering clinician according to the advised timeframe.
- Follow the plan. Repeat testing or treatment should have a clear purpose.
Frequently asked questions
Does a red or bold result mean something serious?
It generally means the result crossed the laboratory’s flagging threshold. Seriousness depends on the amount of change, related results, symptoms and clinical context.
Can a healthy person have an abnormal result?
Yes. Reference intervals do not include every healthy person, and temporary factors can move results. The clinician decides whether follow-up is needed.
Can I have a health problem with normal blood tests?
Yes. No test detects every condition, and reference ranges are not guarantees. Persistent or concerning symptoms still require medical assessment.
Why did two laboratories give different ranges?
They may use different methods, equipment, populations or units. Interpret each result using the interval printed by the laboratory that performed it.
Why has my doctor repeated the test?
Repeating can confirm whether an unexpected result persists, monitor a trend, reduce the effect of temporary factors or assess treatment response.
Should I fast for every blood test?
No. Fast only when instructed. Unnecessary fasting can be uncomfortable or unsafe for some people and does not improve every test.
Why can I see results before my doctor calls?
Most pathology reports uploaded to My Health Record are now accessible immediately. Availability does not mean the result has already been clinically discussed or that a flag is urgent.
Sources and further reading
- Healthdirect: Understanding pathology tests
- Healthdirect: Blood tests A–Z
- Royal College of Pathologists of Australasia: Understanding pathology reports
- RCPA Manual: Pathology tests
- Pathology Tests Explained: Reference intervals
- Pathology Tests Explained: Tips on reading results
- Australian Digital Health Agency: Pathology reports in My Health Record
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