Dilution Linearity
The proportional recovery of analyte when samples are serially diluted, used to assess assay performance and detect interference.
Full Definition
Dilution linearity is a critical analytical performance parameter that evaluates whether an assay maintains proportional response when patient samples are serially diluted with an appropriate diluent (typically assay buffer or hormone-free serum). In hormone testing, good dilution linearity indicates absence of matrix effects, interfering substances, or assay saturation effects. The test involves measuring a high-concentration patient sample at multiple dilution points and verifying that results fall within acceptable recovery limits (typically 80-120% of expected values). Poor dilution linearity may indicate the presence of heterophile antibodies, rheumatoid factor, or other interfering substances that could compromise result accuracy. This parameter is essential for validating sample dilution protocols when results exceed the analytical measuring range.
Usage
Usage note: Also called parallelism in some contexts; ensure consistent terminology within documents.
In Context
- "The TSH sample showed poor dilution linearity, suggesting possible heterophile antibody interference." — Quality control investigation
- "Verify dilution linearity before reporting results from samples requiring predilution." — Standard operating procedure