Which statement is true about quality control in a clinical chemistry analyzer?

• A. Quality control samples monitor assay performance and detect deviations in accuracy or precision.
• B. Calibration is used to define the instrument's response to known standards.
• C. A critical value triggers clinician notification.
• D. Dilution factor is final volume divided by sample volume.

Answer: (A)

Quality control in a clinical chemistry analyzer focuses on ensuring the reliability of test results by running control samples with known concentrations alongside patient specimens. These control materials are used to check how well the assay is performing in terms of accuracy (closeness to the true value) and precision (reproducibility). By tracking control results over time on charts and applying predefined rules, lab personnel can detect shifts, trends, or random errors that signal a problem with the assay, instrument, reagents, or calibration. When a control result falls outside acceptable limits, it prompts investigation and corrective actions to restore reliable performance, ensuring patient results remain trustworthy.

Calibration sets the instrument’s response to known standards and establishes the measurement scale, which is a related but separate process from ongoing quality control.

A critical value pertains to notifying clinicians about life-threatening patient results, not QC monitoring.

Dilution factor relates to sample preparation calculations, not QC performance.