Two labs can measure the same tube of blood, print the same number, and disagree about whether it falls inside the normal range. Neither one is wrong. The range printed beside your result is not a universal constant — it belongs to that laboratory.
Where a reference interval comes from
A laboratory establishes its reference interval by measuring a group of people it considers healthy, then setting its range from the results it observed in that group.
Why the machine matters
Different labs often use different testing methods for the same marker, and the numbers those methods produce are not always interchangeable. A lab pairs its testing method with the reference interval established using that same method.
What this means for a stack of old reports
Comparing a result to the range printed on its own report is comparing like with like. Comparing it to a range from a different lab is not. This is why Arkalife stores the reference range that each report printed, alongside each result, rather than applying one range across every lab.
