Which of the following is NOT listed as an indication that calibration is needed?

• A. Every 6 months
• B. Change of lot number of reagent
• C. Out of range controls
• D. Daily usage spike

Answer: (D)

Calibration ensures measurement accuracy by aligning the instrument’s response to a known standard. Indications to recalibrate typically include a defined maintenance or review plan (like every 6 months), changes in reagent lot numbers that can alter assay performance, and control results that fall outside expected ranges, signaling drift or bias in the system. A daily usage spike, on the other hand, reflects higher sample volume or workload and does not inherently indicate a change in the instrument’s accuracy or calibration status. It may prompt maintenance checks or QC review due to increased wear or throughput, but calibration itself isn’t triggered solely by a rise in daily usage.