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LIMS Result Flags and Critical Values

Dr M H B Ariyaratne edited this page May 22, 2026 · 1 revision

Result Flags & Critical Values

The LIMS includes an automated flagging system that alerts lab staff and clinicians when a patient's result falls outside a defined threshold. Flags can carry custom messages — for example, "Show this result to the doctor immediately" — and can be configured to account for the patient's age and sex. This article explains how flags work, what critical value marking is, and who can act on them.


What Is a Flag?

A flag is a rule attached to a specific investigation parameter. When a result value is entered (or received from an analyzer), the system checks the value against all configured flags for that parameter. If the value meets the flag's conditions, a message is displayed on the result entry screen and printed on the report.

Flags can be triggered by:

  • A numeric range (e.g., flag if serum potassium is above 6.0 mmol/L)
  • The patient's age (e.g., different normal ranges for children vs adults)
  • The patient's sex (e.g., haemoglobin reference ranges differ for males and females)

Types of Flag Messages

Each flag can be configured with up to four different messages:

Message Type When it displays
Flag message A general alert shown whenever the flag condition is met
High message Displayed when the value is above the upper threshold
Low message Displayed when the value is below the lower threshold
Normal message Displayed when the value is within the expected range (optional — used for confirmation prompts)

Each message type can be independently switched on or off. For example, you might enable the high message but not the low message if only the high end is clinically significant.


How Flags Appear During Result Entry

  1. Open the result entry screen for an investigation (Menu > Lab > Report Management > New Report).
  2. Enter a value in a parameter field.
  3. If the value triggers a flag, a coloured indicator and the configured message appear immediately next to the value field.
    • Typically displayed in red for high/critical values and blue or orange for low values, depending on the report format.
  4. The flag message is informational — you can still save and approve the report even when a flag is triggered, unless a validation rule prevents approval (see below).

Flags That Prevent Approval

Some flags are configured as hard stops that prevent the report from being approved until the issue is addressed:

Validation rule What it does
Cannot approve if value is empty Approval is blocked if this parameter has no value entered
Cannot approve if value is below absolute minimum Approval is blocked if the value is physiologically implausible (e.g., negative RBC count)
Cannot approve if value is above absolute maximum Approval is blocked if the value exceeds a defined upper limit

When a hard-stop condition is met, the system displays a warning when the approver clicks Approve, and the report cannot be signed off until the issue is resolved (the value corrected, the sample repeated, or the parameter marked as not applicable).


Critical Value Marking (Requires Immediate Doctor Review)

Beyond automatic flags, an authorised lab user can manually mark a report as requiring immediate physician review. This is the mechanism for escalating truly critical results — values so extreme that a verbal report to the clinical team is warranted before the patient leaves.

How to Mark a Critical Result

  1. Open the report entry screen for the investigation.
  2. Locate the Requires Immediate Doctor Review toggle (only visible if the feature is enabled in your system configuration and if your account has the Lab Authorising privilege).
  3. Switch the toggle on.
  4. A red warning label is added to the report, visible to anyone who opens or prints it.

Clearing the Critical Flag

Once the clinical team has been notified and acknowledged the result, the same authorised user can switch the toggle off to indicate the escalation has been completed.

Note: The Requires Immediate Doctor Review feature must be enabled by the lab administrator. The configuration key is: "MLT allows marking on the report that immediate review by a physician is required." If the toggle is not visible on your screen, this feature is not yet activated for your institution.


How Flags Appear on the Printed Report

When a report is printed, flagged values are displayed with:

  • An H or L indicator next to the value (high or low)
  • The reference range shown alongside for comparison
  • Any configured flag message printed as a footnote or inline comment on the report

The exact appearance depends on the report format configured by the lab administrator.


For Administrators: Configuring Flags

Flags are set up in the investigation's parameter configuration. For each parameter (investigation item), the administrator can define one or more flag rules with numeric thresholds, age/sex filters, and custom messages. See Value Flags in the Administration section.


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