Every laboratory prints a reference range beside your result. Those ranges are not universal. They vary by the equipment used, by the population the laboratory serves, by the method, and sometimes by the country. Two laboratories can print different ranges for the same test and both be correct for their own patients.
The decision
We hold no reference ranges. Not in the app, not in the database. When we explain a result we read the range printed on the document in front of us and explain the value against that.
It would be far easier to store a table and compare against it. It would also be wrong often enough to matter, and wrong invisibly, which is worse.
What this costs
- We need the range to be legible. If a photograph cuts off the range column, we have less to work with and we say so rather than filling the gap.
- We cannot answer about a value in isolation. A number typed into a chat box without its document has no range attached to it.
- We cannot build the features people ask for most. A health score, a traffic light, a single verdict — all of them require a range we have decided not to own.
Why it is still right
The alternative is a product that tells someone their result is abnormal according to a number their own laboratory never used. That is not a small inaccuracy. It is the system substituting its judgement for the judgement of the people who ran the test, silently, in a context where the person has no way to check.
So the range on the page wins. Always.
This article explains how our technology works. It is health information, not medical advice.