It's tempting to take a result from your report, find a "normal range" online, and compare the two. But there's a catch that this whole site is built around: the reference range that genuinely applies to your result is the one printed on your own laboratory report, not the one you found online. Here's why.
Ranges Vary Between Laboratories
Different laboratories use different analysers, methods and procedures. Because of these differences, the reference range for the same test can differ slightly from one lab to another. A range that's correct for the lab that processed your sample may be a little different from a range produced by a different lab using different equipment.
Why Online Ranges Are Only a Rough Guide
General reference sites (including this one) show typical ranges, useful for orientation and for understanding how ranges work. But they can't know which lab processed your sample, which method it used, or the other factors a range can depend on. That's why we say throughout this site that the figures here are for general understanding, and your own report's range is what applies to you.
On top of the lab-to-lab differences, ranges can also be presented differently depending on factors a general site can't tailor to. The safest anchor is always the range that came with your own result.
Reference Ranges Also Change Over Time
Analytical methods evolve, and reference ranges are reviewed and updated as they do. A range that was typical some years ago may have been refined since. This is another reason a current report from the lab that ran your test is more reliable than a figure of uncertain age found online.
How to Use a General Range Sensibly
- Use it to understand the concept, what the test broadly is and roughly where typical values sit.
- Don't use it to judge your own result in place of the range on your report.
- Check the units match before any comparison, as covered in why UK labs use different units.
- For what your result means for you, ask the clinician who can see your full picture.
The Bottom Line
Reference ranges vary between laboratories and change over time, so the range on your own report is the one that applies to your result. General ranges, here or anywhere, are for understanding how things work, not for judging your individual numbers. When it matters, your own report and your own clinician are the authorities.