ISO 15189:2022 · Section 7 · Process requirements
Clause 7.3.5: Biological reference intervals and clinical decision limits
Check the exact requirement in your licensed copy of the standard.
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What this clause is about
Biological reference intervals and clinical decision limits help users interpret results, but they serve different purposes. A reference interval describes a defined reference population under specified conditions. A clinical decision limit supports a particular clinical action or classification and may come from outcome evidence, professional guidance, or an agreed clinical pathway. Neither should be adopted as an unexplained default simply because it appears in an instrument configuration.
For each relevant examination, identify the interpretive limits used, their source, and their intended application. Consider method dependence, calibration, units, specimen type, age, sex where relevant, pregnancy, and other population characteristics that influence interpretation. Decide whether an established interval is applicable locally or whether verification, partitioning, or further investigation is needed. The approach should be proportionate to available evidence and the clinical consequences of inappropriate classification.
Maintain a clear connection between the approved limits, the examination procedure, and the reporting system. Reports should present the appropriate information for the patient and examination context, with helpful qualifications when an interval is not applicable. Staff need to understand the difference between reference information, clinical decision thresholds, and urgent notification limits so these are not confused during configuration or review.
Reassess interpretive limits after relevant method changes, population changes, or new clinical guidance. Communicate significant changes to users and record the rationale and effective date. LabToolkit Pro can help control reference interval review forms and approval records, while clinical and technical specialists remain responsible for selecting and authorizing appropriate interpretive information.
What assessors typically ask to see
- What is the source and intended purpose of each reference interval or clinical decision limit used in reporting?
- How has suitability been assessed for the local method, calibration, reporting units, specimen type, and relevant patient populations?
- How are age groups, other justified partitions, and situations without an applicable interval handled in the reporting system?
- Who authorizes changes, and how are clinical users informed when revised limits could change interpretation of familiar results?
- What distinguishes a reference interval, a clinical decision threshold, and a critical result notification limit in controlled documentation?
- How do method changes or updated clinical guidance trigger review of existing limits and verification of report configuration?
Documents and records that usually provide evidence
- Interpretive limit register identifying examination, units, applicable population, source, rationale, effective date, and responsible approving specialists.
- Applicability assessments documenting method comparability, population considerations, available supporting evidence, and reasons for adoption or further investigation.
- Verification or establishment records showing the selected approach, specimen information, analysis, conclusions, and any limitations on local use.
- Reporting configuration checks confirming correct population partitions, units, displayed intervals, interpretive comments, and handling of missing demographic information.
- Change approval records linking revised limits to technical review, clinical consultation where appropriate, implementation timing, and communication to users.
- Periodic review records identifying new guidance, method changes, user feedback, or population changes that could affect continued suitability.
Common findings to avoid
- Manufacturer intervals are adopted automatically without checking units, calibration differences, or the population for which they were established.
- A clinical decision threshold is labeled as a reference interval, obscuring the purpose and evidence behind its use.
- The approved interval changes in a document but remains unchanged in one interface, report format, or age-specific configuration.
- Users are not informed that a revised method and its new limits may alter interpretation of serial patient results.
How LabToolkit Pro maps documents to this clause
Each SOP, form and record in LabToolkit Pro can carry clause tags. When a document tagged 7.3.5 becomes effective, it counts as direct evidence on the readiness dashboard for ISO 15189:2022; links from other standards through the crosswalk are shown separately as indicative coverage. Gaps appear clause by clause, so you can see which parts of 7.3.5 still need a controlled document or a current record. Readiness is a planning aid — only an accreditation body confirms conformity.
Frequently asked questions
Can the laboratory use published reference intervals?
Yes, when their applicability is critically assessed and supported for the local examination and population. Check the source conditions, method, units, and relevant patient characteristics. Document why the interval is appropriate and what local verification or other evidence supports adoption rather than assuming that publication alone establishes suitability.
Are critical result limits clinical decision limits?
They can overlap in clinical importance, but they serve distinct operational purposes. A critical result limit triggers urgent communication under the laboratory reporting process. A clinical decision limit supports a particular clinical action or classification. Document both clearly and ensure the reporting system applies the right action to each.
What should happen when a method changes?
Assess whether the existing limits remain applicable to the new method, including calibration and expected result differences. Update configuration only after technical approval and check representative report scenarios. Inform users about meaningful changes so historical results, new results, and altered interpretation limits are not compared without the necessary context.
Check the exact requirement in your licensed copy of the standard.
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