In QA/QC, what is the role of positive controls or a test mix?

In QA/QC, what is the role of positive controls or a test mix?

• A. To check patient consent.
• B. To verify assay performance across the panel and confirm reagents and instrument responses are functioning correctly.
• C. To adjust instrument temperature.
• D. To train staff.

Answer: (B)

In QA/QC, positive controls and a test mix exist to confirm that the entire testing process is working as intended. A positive control contains a known target so you can verify the assay will detect it when present, and a test mix combines multiple analytes to check that the assay can accurately respond across the whole panel. This helps ensure reagents are active, calibrators and standards are functioning, and the instrument’s detectors are responding correctly. If the positive control or test mix yields an unexpected result, it signals a problem—perhaps degraded reagents, drift in instrument sensitivity, or a calibration issue—that requires investigation before patient results are reported. These controls are not about obtaining patient consent, adjusting instrument temperature, or training staff; they’re specifically about validating that the assay, reagents, and instrument perform reliably together.

In QA/QC, positive controls and a test mix exist to confirm that the entire testing process is working as intended. A positive control contains a known target so you can verify the assay will detect it when present, and a test mix combines multiple analytes to check that the assay can accurately respond across the whole panel. This helps ensure reagents are active, calibrators and standards are functioning, and the instrument’s detectors are responding correctly. If the positive control or test mix yields an unexpected result, it signals a problem—perhaps degraded reagents, drift in instrument sensitivity, or a calibration issue—that requires investigation before patient results are reported. These controls are not about obtaining patient consent, adjusting instrument temperature, or training staff; they’re specifically about validating that the assay, reagents, and instrument perform reliably together.