After a reagent lot change, which action is appropriate?

• A. Revalidate automatically every time regardless
• B. Do not test and assume no impact
• C. Revalidate the method if necessary
• D. Discontinue use of all QC materials

Answer: (C)

When a reagent lot changes, its performance can differ enough to affect results, so you should revalidate the method with the new lot if necessary. This means you verify that accuracy, precision, and other method performance characteristics still meet predefined acceptance criteria by testing with the new reagent (often including running controls and comparing to prior data). If the new lot passes, you can continue using it; if it doesn’t, you may need adjustments and additional validation before proceeding. Automatic revalidation every time or skipping testing and assuming no impact aren’t appropriate, and discarding all QC materials isn’t warranted by a reagent lot change.