Understanding blood test reference ranges

How do I get the reference range for my test?

You have a right to see your full test results. You can ask your GP surgery or hospital clinic for a copy of the laboratory report. This will include the reference range used.

If you live in England or the Isle of Man you can get GP test results on the NHS app. These should show your results and the reference ranges used.

Some hospitals also allow you to see test results online or via an app.

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What does my test result mean?

You might get your result and the reference range as numbers. Or as a diagram that looks a bit like this:

In this example, any result that was above 35 and below 50 would be in the reference range. This image is an example, you may be given a different range for this test.

You can find out more about understanding laboratory reports here.

Different labs also use different units for their results. For example, g/L (grams per litre) or IU/L (international units per litre). This is another reason why you should only use the reference range from the lab that did your test.

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How is the reference range set?

Different labs use different equipment and have slightly different ways of doing each test. Because of this, each lab sets their own reference ranges.

The range is set by doing the test on a large number of people who are thought to be healthy. Because results vary a lot from person to person, the laboratory works out the range that would include 95% (19 in 20) of those tested. This is the reference range.

This means that 1 in 20 of the healthy volunteers have a result outside the reference range.

Some tests have more than one reference range. For example, there might be different reference ranges depending on:

• Age
• Ethnicity
• Pregnancy
• If you are male or female

Find out more about understanding your test results for a liver blood test.

Find out more about understanding reference ranges here.

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Special thanks

We would like to thank everyone with lived experience of liver disease tests who helped with these pages. Including, Sejal Patel, and Jennifer Voller.

Also, Professor Stephen Ryder, consultant hepatologist at Nottingham University Hospitals NHS trust and Dr Laura-Jane Armstrong, Associate GP, Avonside Health Centre, for reviewing this page.

Published: July 2025

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