Clarification Regarding the Use of Control Materials as Calibrators to Determine Test Cut-off Values

• Controls as Calibration Materials: Controls provided by manufacturers in a test kit are considered to be calibration materials if they are used to calculate the cutoff value of a test or a patient test result.
• Testing of Additional External Controls: If the manufacturer’s instructions include a formula which uses the positive and/or negative controls included in the kit to determine the cutoff, additional external positive and/or negative controls must also be tested.
• Guidance for Surveyors: The laboratory director is responsible for the determination of what control materials to use in his/her laboratory. Surveyors will ensure that the laboratory is following its own established policies, specifically its Quality Control (QC) procedures.