REFERENCE RANGE
What does “reference range” mean on my lab results?
A reference range is the span of results found in most healthy people for that test, at that lab, using that method. It is printed beside your result so you can see where it sits — but a result just outside the range is not necessarily a problem, and one inside it is not a guarantee.
Why it’s confusing
Ranges look like pass/fail limits, and a result one point outside gets a flag that feels alarming. But ranges are set from large groups of healthy people, so it is common for a healthy person to sit outside one now and then.
Ranges also differ between labs, because labs use different equipment and methods. A range you find online may not apply to your report.
How to read it
Read your result against the range printed on your own report, in the same units. MedlinePlus is clear that you can’t compare your results with reference ranges found elsewhere.
Look at how far outside the range a result is, and whether related results are also outside. Then look for any comment from the lab.
Some tests have different ranges for different groups — children and adults, for example — and the lab chooses the range that fits the person tested.
Your doctor reads results alongside your history, symptoms, medicines and earlier results, which is why the same number can mean different things for different people.
What it does not mean
- That a flagged result means you are ill. Healthy people sometimes fall outside a range.
- That a result inside the range means everything is fine. Some people with health problems have results in range.
- That two labs’ results can be compared directly. Check the units and ranges first.
Where you’ll see it
- Every lab report, usually in a column next to your result.
- Patient portals, sometimes as a bar or a shaded band.
Questions worth asking
Ask your doctor
- Which of my results outside the range matter for me?
- Do any results need repeating?
- How do these compare with my earlier results?
Got results with flags you don’t understand? Attach the report or paste the text, and Clariti will explain each line.
Common questions
- Why are reference ranges different between labs?
- Labs use different equipment and testing methods, so each sets ranges for its own tests. Use the range on your own report.
- Is a result slightly outside the range bad?
- Not necessarily. Ranges are based on healthy people and some healthy people fall outside them. Your doctor interprets results in context.
- Is a reference range the same as a target?
- No. A range describes results in healthy people. Some tests, such as cholesterol or HbA1c, also have targets that depend on your own health — your doctor sets those.
Sources
Reading a scan report rather than a blood test or letter? Radily’s radiology report phrase guides explain the wording radiologists use.