Dr Kathryn Fox is an Australian medical doctor and bestselling crime writer, best known for her forensic thrillers featuring pathologist Dr Anya Crichton. Drawing on her medical expertise, she crafts gripping, authentic crime fiction and is also a passionate advocate for forensic medicine education and public engagement.
It’s a familiar moment. Blood tests are back and the doctor wants to see you. You scan the results that resemble a secret code of letters, signs and numbers.
Your eyes go straight to the lines marked in red.
But here’s something many doctors wish patients knew: Not every abnormal result is dangerous. On the other hand, “normal” results don’t guarantee perfect health.
Blood tests are tools, pieces in a puzzle, not a complete picture. They provide clues that need to be interpreted in context: your age, symptoms, medications, and overall health.
Here are some of the results people worry about most – and what they often mean.
Cholesterol numbers cause a lot of anxiety. But a single “high” reading doesn’t automatically mean you need medication.
Doctors look at a series of results including LDL (“bad”) cholesterol, HDL (“good”) cholesterol, triglycerides, blood pressure, diabetes status, smoking and family history.
The Heart Foundation of Australia advises that treatment decisions are based on overall cardiovascular risk, not just one number.
For many people, especially if the rise is mild, lifestyle changes like diet and exercise may be recommended first.
Seeing a reduced eGFR, which is measure of the kidney’s ability to filter waste, can be disturbing.
But kidney function naturally declines as we age. A mildly reduced result may simply reflect normal ageing.
Kidney Health Australia notes that doctors look to see if the results are stable over time, whether there are changes in other kidney markers in both blood and urine and the presence of underlying conditions like diabetes or high blood pressure
A sudden drop is more concerning than a long-standing, stable result.
A slightly raised fasting glucose or HbA1c can indicate pre-diabetes, which means blood sugar levels are higher than ideal but not yet in the diabetes range.
Diabetes Australia highlights that early changes are often reversible with lifestyle adjustments such as weight management, diet and physical activity.
Borderline results are often a warning sign – not a diagnosis. It’s also an opportunity to make some health changes with long term benefits.
Liver enzymes can rise for many reasons, including medications, alcohol consumption, fatty liver disease, viral infections and may occur with temporary illnesses.
Mild abnormalities are common and often reversible.
Doctors usually monitor trends and may repeat testing before deciding whether further investigation is needed.
Low iron, vitamin B12 deficiency, chronic disease or hidden bleeding can all contribute to anaemia. They can be related to too little taken in, too much lost or excreted, or the body not absorbing or metabolising essential nutrients properly
The Royal Australian College of General Practitioners advises that anaemia in older people often requires further investigation to identify the cause.
Fortunately, many causes are treatable once identified and can prevent more serious illness.
Thyroid hormones regulate metabolism and energy.
Low thyroid levels can cause fatigue, weight gain and brain fog. An overactive thyroid can cause anxiety, tremor and palpitations.
Thyroid disorders become more common with age and are usually straightforward to treat.
Slight fluctuations can occur, so doctors often repeat tests before making decisions.
Tests like CRP and ESR measure inflammation in the body. They are what’s called non-specific markers and don’t point to a specific disease. Instead, they indicate that something may be causing inflammation — such as infection, arthritis or autoimmune conditions.
A mildly raised result is not uncommon and usually needs to be interpreted alongside symptoms and other conditions.
Medicine isn’t about treating numbers – doctors treat people. A result that looks concerning on paper may be expected for your age, medical history or medications.
Conversely, a “normal” result doesn’t always rule out problems if symptoms are present. It’s why pathology reports are guides, not diagnoses.
Questions Worth Asking Your GP
If a result worries you, consider asking:
“Is this normal for my age?”
“Has this changed compared to last time?”
“Does this need treatment or monitoring?”
“Is there anything I can improve with lifestyle?”
Often, trends over time matter more than single readings.
Blood test results can look intimidating, especially when numbers fall outside reference ranges. But “abnormal” doesn’t always mean dangerous.
In many cases, it means your doctor has identified something early — while it’s still manageable.
Understanding your results is part of taking charge of your health. And sometimes, the most important result isn’t the number. It’s where it fits in the bigger picture.