How are internal QC control materials selected and what acceptance criteria are typically used?

How are internal QC control materials selected and what acceptance criteria are typically used?

• A. Choose materials with unknown concentrations to challenge the assay.
• B. Choose materials with very wide concentration ranges.
• C. Choose materials with known concentrations near medical decision levels; acceptance criteria are predefined tolerances (±% or concentration) based on method validation.
• D. Choose any available material regardless of validation.

Answer: (C)

The main idea is that internal QC materials should be known at concentrations that matter for patient decisions, so you can reliably monitor assay accuracy and precision where it counts. Using materials with known concentrations lets you measure bias (how close you are to the true value) and precision (how repeatable the result is). Placing QC near medical decision levels targets the points at which an assay’s performance most directly affects patient care, so any drift or error is detected before it could lead to a mistaken decision. The acceptance criteria are predefined tolerances established during method validation, specifying how far QC results may deviate (for example, a percentage around the target concentration or a fixed allowable difference) while still being considered acceptable. This creates a consistent standard for ongoing quality control and helps ensure the method remains fit for purpose. Materials with unknown concentrations cannot reveal how accurate you are to a true value, and using very wide concentration ranges or arbitrary materials without validation can hide problems or produce misleading QC results.

The main idea is that internal QC materials should be known at concentrations that matter for patient decisions, so you can reliably monitor assay accuracy and precision where it counts. Using materials with known concentrations lets you measure bias (how close you are to the true value) and precision (how repeatable the result is). Placing QC near medical decision levels targets the points at which an assay’s performance most directly affects patient care, so any drift or error is detected before it could lead to a mistaken decision. The acceptance criteria are predefined tolerances established during method validation, specifying how far QC results may deviate (for example, a percentage around the target concentration or a fixed allowable difference) while still being considered acceptable. This creates a consistent standard for ongoing quality control and helps ensure the method remains fit for purpose.

Materials with unknown concentrations cannot reveal how accurate you are to a true value, and using very wide concentration ranges or arbitrary materials without validation can hide problems or produce misleading QC results.