Understanding your blood test results

A blood test report lists each marker you were tested for, your result, the units it's measured in and a reference range showing where most healthy people fall. Results outside that range are usually flagged high or low. A flag isn't a diagnosis, though. What a result means depends on your history, your symptoms and your other results, which is why a doctor should always go through them with you.

The parts of a results report

Most Australian pathology reports follow a similar layout. For each test you'll see the following.

• The test name, sometimes abbreviated, such as Hb for haemoglobin or TSH, a common thyroid marker.
• Your result, as a number.
• The units, such as mmol/L or g/L. These matter, because the same marker can be reported in different units.
• The reference range, the span of values the lab considers typical.
• A flag, often H or L, if your result falls outside that range.

Some reports also include comments from the pathologist. These can be useful, so don't skip them.

What reference ranges really mean

A reference range is usually based on results from a large group of healthy people. It's set so that most of them fall inside it. That has an important consequence. Some perfectly healthy people will fall slightly outside the range, simply because of normal variation.

Ranges can also differ by age, sex and sometimes pregnancy, and between laboratories, because labs use different equipment and methods. Always compare your result against the range printed on your own report, not one you've found online.

High and low flags

A flag tells you your result sits outside the reference range. It doesn't tell you why, or whether it matters.

A result just outside the range, with no symptoms and everything else in order, might simply be noted and rechecked later. A result well outside the range, or one that fits with how you've been feeling, may need more attention. Things like dehydration, a recent illness, hard exercise or not fasting when you should have can all shift results temporarily. That's one reason how to prepare for a blood test is worth reading before your next one.

Normal isn't the end of the story

It's easy to see a page with no flags and assume there's nothing more to learn. Often that's true. But sometimes a result inside the range is still worth discussing.

For example, a marker may sit near the edge of the range while you have symptoms that fit. Or it may have changed noticeably since your last test, even though both results are technically normal. Trends over time often tell a doctor more than a single snapshot, so keep copies of your past results if you can.

Looking at results together

Individual markers rarely tell the whole story. Doctors tend to read results in groups. Iron studies, for instance, include several measurements, such as ferritin, that are interpreted together. Thyroid tests, full blood counts, kidney and liver function, blood sugar markers like HbA1c and lipid panels each work the same way.

A doctor then puts those groups alongside your symptoms, history and medications. That's how a set of numbers becomes a clear picture. If you'd like to understand some of the common groups in more depth, see metabolic blood tests explained.

Questions to ask your doctor

When you go through your results, it helps to have a few questions ready. Which results are outside the range, and does that matter for me? Have any results changed since my last test? Do any results explain how I've been feeling? Should anything be rechecked, and when?

It's also worth asking what, if anything, you should do differently before your next test, so results can be compared fairly. Write the answers down, or ask for them in writing, so you're not relying on memory.

Try not to diagnose yourself from a search engine. Online information can't account for your full situation, and it often makes ordinary variations sound alarming.

Having your results reviewed with UHD BioHealth

At UHD BioHealth, an AHPRA-registered doctor reviews your detailed online questionnaire and makes contact within 24 hours. Where bloodwork is recommended, you visit a local collection centre, and your doctor explains your results in a written personalised plan covering the reasoning, safety checks, follow-up schedule and every cost itemised, which you read before paying anything. To begin, start your assessment.