scope:

This guideline is intended for manufacturers and medical laboratories, for two purposes:

• Assist manufacturers and other developers of laboratory measurement procedures in characterizing the effects of potential interferents on measurement procedures results by providing information on:

- Relevant interferents and concentrations to be tested

- Likely effects of the interferent on the concentration of the measurand of interest (ie, no effect, positive effect, or negative effect)

- Scientifically valid experimental designs

- Appropriate data analysis and interpretation

- Stating meaningful interference claims

• Assist medical laboratories in investigating discrepant results that may be due to interferents by:

- Defining a systematic investigation strategy

- Specifying data collection and analysis procedures

- Promoting greater cooperation between laboratory scientists and manufacturers so that new interferents are identified, disclosed, and ultimately eliminated

Any measurement procedure, quantitative or qualitative, may be subject to interference. This guideline is written for a broad spectrum of measurement procedures and measuring systems, with primary focus on quantitative methods and qualitative methods with interpretation based on numeric values. Modification may be necessary to accommodate the particular characteristics of the procedure being evaluated. Measurement procedures that use serum, plasma, whole blood, cerebrospinal fluid, urine, and most other body fluids can be evaluated for interferents using this guideline.

EP07 and its supplement, CLSI document EP37,¹ are not meant to include a complete list of interferents to be tested and do not stipulate that all potential interferents included in CLSI document EP37¹ are to be tested. However, EP07 and CLSI document EP37¹ are intended to provide a solid starting point for assessing interference effects. This guideline is limited to testing potential interference from chemical substances that may be exogenous (eg, drugs) or endogenous changes in concentrations of substances caused by disease processes (eg, bilirubin, lipoproteins).

This guideline does not cover potential interference from physiological conditions (eg, pregnancy, diurnal effects) or effects from environmental conditions (eg, heat, sunlight).