Calibration Traceability in Medical Labs — What NABL Requires

Calibration traceability is a fundamental requirement of ISO 15189:2022 and NABL accreditation. It ensures that your measurement results are connected to national and international reference standards.

When your lab reports a haemoglobin value of 12.5 g/dL, how do you know that value is accurate? Calibration traceability is the chain of comparisons that connects your measurement to a national or international reference standard — the answer to that question.

What is Calibration Traceability?

Traceability is the property of a measurement result whereby the result can be related to a reference through a documented unbroken chain of calibrations, each contributing to the measurement uncertainty.

Traceability Chain

1. International reference standard (SI unit, certified reference material)
2. National reference standard (NABL-accredited primary lab)
3. Secondary calibration standard (your calibration laboratory)
4. Your working standard / instrument calibrator
5. Your measurement result

Practical Requirements for Labs

• All critical instruments must be calibrated by NABL-accredited calibration laboratories
• Calibration certificates must show the traceability statement and associated uncertainty
• Calibration frequency must be defined in your equipment SOP (based on manufacturer recommendation and stability data)
• All calibration records must be maintained for the life of the equipment plus 2 years

Common Calibration Traceability Non-Conformances

• Using non-NABL-accredited calibration services
• Calibration certificates without traceable reference statements
• Calibration interval not defined in equipment SOP
• Equipment used while awaiting calibration (no interim measures)