Lab Methods Flashcards
Y-axis of Receiver Operating Characteristic Curve
Sensitivity
X-axis of Receiver Operating Characteristic Curve
False positive rate (1 - specificity)
Receiver Operating Characteristic Curve is a plot of these values
Likelihood ratios
Type of reference range that uses a Gaussian distribution and +/- 2 standard deviations from the mean
Default reference range
Type of reference range where the values may lie on a Gaussian distribution, but many values within the central 95% are not desirable
Uses recommendations based on research and clinical experience to establish “desired values”
Prognosis/treatment derived range
Cholesterol and blood pressure use this type of reference range
Prognosis/treatment derived range
Type of reference range that determines a value that, when exceeded, indicates disease
For metabolites that are not normally found in the blood
Threshold value
Cardiac markers and drugs of abuse screens utilize this type of reference range
threshold value
Type of reference range that establishes a “therapeutic window” for drug levels
Established by experimentation and clinical data to maximize drug effectiveness and minimize toxicity
Therapeutic drug range
Screening tests often intentionally have a high false _____ rate
False positive
goal is to capture all possible disease
Which has a high specificity: screening or confirmatory tests?
Confirmatory test
Which has a high sensitivity: screening or confirmatory tests?
Screening test
formula that links test accuracy with likelihood of disease (pre-test probability) to determine post-test probability
Bayes Theorem
Accuracy in the Bayes Theorem refers to these 2 values
Sensitivity and specificity
Likelihood / pre-test probability in the Bayes Theorem refers to this value
Prevalence
When ordering tests, you should select order tests first with lower to higher _____?
Specificity
Most common type of lab test errors
Pre-analytical
Least common type of lab test errors
Analytical
Second most common type of lab test errors
Post-analytical
2 interfering substances in spectrophotometry
Bilirubin and lipids
Source of error in ELISA and Latex Agglutination where Analyte concentration is so high that it binds all sites on both capture Ab and Detector Ab
Gives falsely low measurement
Hook Effect
Anti-animal antibodies in the patient during an ELISA gives falsely high or low measurement?
High
Hook effect in ELISA gives falsely high or low measurement?
Low
Clinical laboratory test where presence of analyte results in clumping of Ab coated beads
Detected as a change in turbidity
Latex Agglutination
