pre-analytical variables
Factors affecting sample quality and analyte stability before laboratory analysis in newborn screening programs.
Full Definition
Pre-analytical variables encompass all factors that can influence newborn screening test results before the sample reaches the analytical phase of testing. These variables include timing of sample collection relative to feeding and age, sample collection technique, filter paper type and storage conditions, transportation methods, ambient temperature and humidity exposure, and duration between collection and analysis. Proper control of pre-analytical variables is crucial because many screening analytes are sensitive to degradation, evaporation, or chemical modification under suboptimal conditions. Understanding and minimizing pre-analytical variation is essential for maintaining test sensitivity and specificity, reducing false positive and false negative rates, and ensuring reliable screening results across diverse collection environments.
Usage
Usage note: Hyphenate when used as compound modifier; plural form typically used when referring to multiple factors.
In Context
- "Pre-analytical variables contributed significantly to the observed increase in false positive rates." — Quality assurance investigation
- "Training programs emphasize controlling pre-analytical variables to maintain screening accuracy." — Educational material