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The need to calibrate an instrument before performing a new reagent lot check varies by test system. The instructions for some instruments require recalibration when introducing new reagent lots. Therefore, laboratories need to review the recalibration criteria in the manufacturer’s instructions, including how often to recalibrate, and consider their past experience with the instrument.

The CAP Laboratory Accreditation Program requires laboratories to recalibrate or perform a calibration verification of instruments when changing reagent lots unless laboratories can demonstrate that using different lots does not affect the accuracy of patient test results. Data from reagent lot-to-lot studies that used specimens at different concentrations can be evaluated to determine if the instrument needs to be recalibrated.

Using patient samples for new reagent lot studies is considered best practice because it eliminates the possibility of a matrix effect. Requirement COM.30450 in the CAP’s all common checklist provides examples of additional materials that may be used for these studies, such as reference materials or QC products provided by the method manufacturer with method-specific and reagent lot-specific target values and proficiency testing materials with peer group-established means. Refer to the checklist note in COM.30450 for a more comprehensive list of examples.

Clinical and Laboratory Standards Institute. EP26-A: User Evaluation of Between-Reagent Lot Variation; Approved Guideline, 1st ed.; 2013.

Miller WG, Myers GL, Rej R. Why commutability matters. Clin Chem. 2006;52(4):553–554.

Standard: Calibration and Calibration Verification Procedures. 42 CFR §493.1255(b)(3). https://bit.ly/493-1255b3

Lyn Wielgos, MT(ASCP)
Checklist Editor
CAP Accreditation Programs
College of American Pathologists
Northfield, Ill.