ISO 18153:2003

Overview

ISO 18153:2003 - In vitro diagnostic medical devices - Metrological traceability of values for catalytic concentration of enzymes assigned to calibrators and control materials - defines how to assure metrological traceability for calibrators and control materials supplied with or for use with in vitro diagnostic (IVD) medical devices. The standard focuses on establishing a clear calibration hierarchy and traceability chain so values assigned to enzyme catalytic‑concentration calibrators and controls can be validated against higher‑order reference measurement procedures and, where possible, the coherent SI unit (katal per cubic metre).

Key Topics

• Metrological traceability chain and calibration hierarchy
  • Hierarchical structure from SI unit (kat m‑3) and primary reference measurement procedures down to routine calibrators and control materials.
  • Emphasis on internationally agreed primary procedures (e.g., IFCC reference measurement procedures) as part of the measurand definition.
• Measurand definition
  • An enzyme measurand is procedure‑dependent; it must specify substrate, activators, direction of reaction, indicator component, buffer and pH, temperature, incubation and reaction times, lag time and starting material.
• Validation of traceable calibration
  • Principles and requirements to demonstrate that assigned values are traceable and valid for establishing or verifying trueness of measurement.
• Analytical specificity
  • Requirements related to the specificity of measurement procedures for the catalytic activity being measured.
• Commutability
  • Criteria and assessment of commutability for both calibrators and control materials (i.e., how closely reference materials mimic routine patient samples across procedures).
• Scope exclusions
  • Not covering design/selection of reference methods, mass or immunoreactivity quantities, unassigned precision control materials, intralaboratory QC consensus intervals that are not metrologically traceable, or metrological traceability of routine results to product calibrators vs. medical decision limits.

Applications

• Manufacturers of IVD enzyme assays: use ISO 18153 to assign and validate traceable values for product calibrators and control materials.
• Clinical and medical laboratories: understand traceability expectations for enzyme measurements and select appropriate calibrators and controls.
• Reference and metrology laboratories: develop and apply primary reference measurement procedures and certified reference materials consistent with the calibration hierarchy.
• Regulators and conformity assessment bodies: assess manufacturer claims about traceability and trueness for enzyme catalytic‑concentration assays.

Related Standards

• ISO 17511 (metrological traceability for biological quantities) - normative reference for calibration hierarchies in IVDs.
• VIM (International Vocabulary of Metrology) and GUM (Guide to the Expression of Uncertainty in Measurement) - referenced for terminology and uncertainty principles.
• IFCC primary reference procedures (listed in Annex A of ISO 18153) and certified reference materials (Annex B) are identified as supporting resources.

Keywords: ISO 18153:2003, metrological traceability, catalytic concentration of enzymes, calibrators, control materials, IVD, calibration hierarchy, commutability, IFCC, katal per cubic metre.