---
title: "Reference ranges"
description: "How to show a value against a range without implying a diagnosis, and why the word \"normal\" is banned from every user-facing string about a person's own result."
url: "https://opsinjs.pensievelabs.org/health/reference-ranges"
source: "https://opsinjs.pensievelabs.org/health/reference-ranges.md"
section: "Health"
kind: "health"
evidence: "mixed"
reviewed: "2026-09-02"
reviewer: "design"
aliases: ["normal", "abnormal", "out of range", "healthy range", "cut-off", "reference interval"]
implements: ["range-bar", "result-card", "metric-tile", "value", "range-legend", "disclaimer-note", "score-dial"]
---
> Elements written as `` below are opsinjs documentation
> components. Their attributes are the content: the values they render are
> generated from `tokens/*.json` and `registry/catalogue.ts` and are
> published separately at https://opsinjs.pensievelabs.org/r/index.json and under the Reference
> section.
> Nothing is missing from this page. The data simply does not live in
> the prose.
## What this means [#what-this-means]
A reference range is a statistical statement about a population, usually
constructed so that a defined majority of an apparently healthy reference group
falls inside it. It is produced by a specific laboratory, using a specific assay,
for a specific population, and it varies between laboratories for the same test.
That definition supports neither of two conclusions a reader may draw from it. It
does not say that a value inside the range is healthy. It does not say that a
value outside it is disease. By construction, a proportion of perfectly well
people fall outside (that is what "a defined majority" means), and a person can be
seriously unwell with every value comfortably inside.
A conventional range visualisation prints the range as a bar, the value as a dot,
and labels the middle "Normal". A band labelled "Normal" is reasonably read as a
statement about the person rather than about the measurement, and the negation of
that statement has no gentler form in English: a reader whose value sits outside
the band has been told they are not normal, and no statistical caveat placed
beside the bar survives contact with the word.
The misreading is produced by the wording and the layout rather than by the
measurement or by the range behind it. Wording and layout are the presentation
layer's responsibility, which places this failure inside opsinjs's scope rather
than the issuing laboratory's.
## The rule [#the-rule]
**Show the value, show the range it is being compared against, name whose range
it is, and never characterise the person.**
### Banned words in user-facing strings [#banned-words-in-user-facing-strings]
Each word below is banned from any user-facing string about a person's own
result, and the *Use instead* column is the replacement wording this system
specifies.
| Banned | Because | Use instead |
| ------------------- | ------------------------------------------------------------------------------------------------------------------------ | ---------------------------------------------------- |
| normal / abnormal | Describes the person, not the measurement; its clinical sense and its lay sense are different words spelled the same way | "in the usual range" / "outside the usual range" |
| healthy / unhealthy | A verdict on a life, from one number | "in the usual range" / "higher than the usual range" |
| good / bad | Moral framing of something largely outside the reader's control | Say the direction: "higher", "lower" |
| poor / failed | Failure language for a body | "lower than expected" |
| perfect / optimal | Sets up every future reading as a decline | "in the usual range" |
| positive / negative | Inverted in lay usage, where a "positive" result is usually the bad one | Name the finding: "X was found" / "X was not found" |
| elevated | Clinical register; means little to a lay reader | "higher than" |
### Presentation rules [#presentation-rules]
| # | Requirement | What must be visible on screen | Who owns it | Failure it prevents |
| - | -------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------ | -------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------ |
| 1 | **The range is always attributed.** The surface names whose range it is at the point where the comparison is made. | "Your laboratory's usual range", or "the range this device uses", next to the band itself. | The laboratory, the device manufacturer or the clinical team that issued the range | An unowned band read as a threshold the product or opsinjs set for itself |
| 2 | **The range is shown rather than merely applied.** | The endpoints of the range, beside the value being compared with them. | The supplier of the range owns the endpoints; the implementing team owns whether they reach the screen | A status pill without a visible range asks the reader to trust an invisible rule |
| 3 | **A small change near the boundary produces a small change on screen.** A value just outside a range is presentationally close to one just inside. | The distance between the value and the boundary, so that "just outside" and "far outside" can be told apart. | The implementing team, because the treatment either side of the boundary is a presentation decision | A one-unit change flipping the whole surface from calm to alarming with nothing in between |
| 4 | **Direction is stated in words.** | The direction in words, for example "higher than the usual range", and not only the position of a dot along a bar. | The implementing team, writing the string | Direction recoverable only by a reader who can see and interpret the dot's position |
| 5 | **Nothing on the surface asserts a cause.** | The observation only: "Higher than the usual range" is an observation and "You may be dehydrated" is a diagnosis. | The reader's clinician; no surface in the product attributes a cause | An observation read as a diagnosis the presentation layer is not entitled to make |
| 6 | **Only a range built for the reader's population is shown.** A range derived from an adult population is not shown to a reader who is fifteen. | No range at all, where none of the available ranges covers the reader. | The supplier of the range, who also defines the population it was constructed from | A status manufactured from a comparison that does not hold for this reader |
| 7 | **The reader can always see the raw value.** | The value itself, with its unit, alongside any gauge, bar or dial drawn around it. | The laboratory or device that produced the measurement owns the value; the implementing team owns keeping it visible | A gauge standing in for a number the reader can no longer recover |
"Why (evidence)" below classifies rule 3 as opinion and does not classify the
other six.
The values in any range demonstration in these docs are placeholders chosen to
show formatting. They are not reference ranges and must not be copied into a
product.
## Why (evidence) [#why-evidence]
**Cited.** How laboratory results are presented to patients has been studied
directly. The 2024 systematic review of laboratory-result presentation formats
in JMIR, [10.2196/53993](https://doi.org/10.2196/53993), examines the formats
used to communicate results to patients and their effects on comprehension. The
2018 study in BMC Medical Informatics and Decision Making,
[10.1186/s12911-018-0589-7](https://doi.org/10.1186/s12911-018-0589-7),
examines patient-portal presentation of results specifically. We cite both as
the anchors for the claim that presentation format materially changes what a
lay reader takes away from a number, and that a bare value with a reference
interval, which is the format a portal inherits from a laboratory report, is
ill-suited to a lay reader.
This page extracts no specific effect size and no specific recommendation from
either paper. Both are short and are cited here to be read rather than
summarised.
**Opinion.** The banned-word list in this section is ours and rests on no
citation. "Normal" is the entry we hold most firmly, and the argument for it is
linguistic rather than empirical: the clinical sense of "normal" (within a
reference interval) and the lay sense (unremarkable, acceptable, not wrong with
you) are different words that happen to be spelled the same, and the interface
has no way to signal which one it means. The antonym carries the same ambiguity
in reverse, and a reader told they are "abnormal" receives a description of
themselves that the interface cannot qualify.
Rule 3, which requires that a small change near the boundary produces a small
change on screen, is also opinion, and it has a real tension with clarity: a
clear boundary is easier to read. We accept slightly less clarity to avoid the
failure where a value moving by less than the measurement error changes the
emotional content of the whole screen.
What would change our mind: evidence that lay readers correctly interpret
"normal" in its statistical sense in context, which would revise the first row
of the banned-words table and leave the seven presentation rules standing.
## Applying it [#applying-it]
"5.4 mmol/L. In your laboratory's usual range (3.9 to 5.6 mmol/L)." The
string carries the value, the comparison, the owner of the range and the
range's endpoints.
"5.4 Normal ✓". The tick and the word together assert a verdict on the
person, and the surface shows neither the range nor whose range it is.
"Slightly above your laboratory's usual range. This often needs no action on
its own. Your clinician will look at it alongside your other results." The
string states the direction, attributes the range and names who will
interpret it.
"ABNORMAL out of range." The string applies a clinical adjective to the
reader in capitals, gives no indication of how far outside the range the
value sits, and reaches someone who cannot ask a follow-up question until
Monday.
Render the range as a labelled band with its endpoints visible, and put the
value inside it. A reader can then judge "just outside" versus "far outside"
for themselves.
Render a red-to-green gradient with no numbers. A gradient asserts a
continuous quality scale that reference ranges do not have, and it carries
nothing at all in greyscale.
Where sex-, age- or pregnancy-specific ranges exist, use the one that applies
and say which: "usual range for adults over 18".
Apply one adult range to everyone because it is the one in the config file. A
range built for a population the reader is not in manufactures a status from a
comparison that does not hold.
## Components that implement this [#components-that-implement-this]
{/* Generated from `implements`. Do not restate the list by hand. */}
`RangeBar` is specified to require an attributed range, so a bare pair of numbers
with no owner is a validation error rather than a rendered bar. The banned-word
list above is expressible as a lint rule over user-facing strings, and until such
a rule exists the check falls to review.
## What this does not cover [#what-this-does-not-cover]
* **The ranges themselves.** opsinjs ships no reference ranges for any metric.
They are supplied by the laboratory, the device manufacturer or the clinical
team behind the product, and each one arrives with an owner.
* **Deciding a status from a range.** Being outside a range is not automatically
`attention`; see [Clinical status semantics](./clinical-status-semantics.mdx).
* **Number formatting.** The canonical treatment is at
[Numbers, units and precision](./numbers-units-precision.mdx).
* **Risk expressed as a probability.** Risk stated as a probability rather than
as a range is covered at [Risk and statistics](./risk-and-statistics.mdx).
* **Composite scores.** A score with no reference interval at all has band names
invented by the product, and those names must be disclosed as such.
* **The wider vocabulary.** Full plain-English replacements live at
[Plain-English A to Z](../content/plain-english-a-z.mdx).
## Updates to this page [#updates-to-this-page]