Must To Know - Fast Track Flashcards
Unit prefix in metric system of units denoting a factor of 1 million (1 x 10^6).
Mega
Constant error
Error where there is continual difference between test and comparative method values.
Proportional Error
Error where difference between test and comparative method values are proportional to analyte concentration.
3:3
Ratio of warning to mandatory Westgard rules.
Levi-Jennings
- QC chart that demonstrates the Westgard rules.
2. Most widely used QC chart in the clinical laboratory.
Youdin Twin Plot
QC chart that is used to compare results to different laboratories.
CuSum Graph
Plot that gives the earliest indication of a trend.
Accuracy
Closeness of measured values to the true value.
Sensitivity and Specificity
- Measures of the diagnostic accuracy of the test.
2. Important criteria in evaluating instruments.
Diagnostic Sensitivity
- Ability to detect the presence of the disease.
- Indicates the ability of the test to generate more true (+) and few false (-) results.
- Reflects the ability of the method to detect true (-) result with very few false (+) results.
Positive Predictive Value (PPV): Function
Indicates the number of patients with an abnormal test result who have the disease.
Positive Predictive Value (PPV): Formula
(true positives)/(true positives + false positives)
Negative Predictive Value (NPV): Function
Indicates the number of patients with a normal test result who do not have the disease.
Negative Predictive Value (NPV): Formula
(true negatives)/(true negatives + false negatives)
Central tendency; Dispersion
Parts of descriptive statistics.
Variance, SD, CV, Range
Measures of dispersion.
The lower the CV, the _____ the precision.
higher
Mean
The average of a given set of values.
Median
Middle or midpoint of distribution.
Mode
Most frequent observation in a set of data.
Mean, Median, Mode
Normal Gaussian distribution curve.
Proficiency Testing (EQA)
Evaluation of method performance by comparing results with other lab.
Delta check
Comparison between patient’s most recent result and previous determined value.
Good Standard Curve
- Line is straight
- Line connects all points
- Line goes through the origin of x and y axis
There is perfect correlation of values in linear regression if value falls on __.
1
Point of care testing
Test performed usually by non-laboratorian personnel (nurses, RTs, etc.)
Specimen used for point of care testing (POCT)
Capillary blood
QC of POCT instruments should be done ___________________.
once each day of use
Clerical error
Usual cause of error in the laboratory
Colligative properties
vapor and osmotic pressure; boiling and freezing points
Spectrophotometer
Instrument that uses diffraction gratings (as commonly used monochromators).
Beer’s law
Mathematically establishes relationship between concentration and absorbance.
Formula for the concentration of an unknown sample (using spectrophotometer)
- (Au/As) x Cs
2. Gold/Arsenic x Caesium
Visible region
400nm - 700nm
UV region (very short wavelength)
<400nm
IR (infrared radiation) region
> 700nm
Tungsten lamp
Light source in the visible region.
Light sources in the UV region:
- Mercury arc
- Deuterium lamp
- Hydrogen lamp
- Xenon lamp
Light sources in the IR region:
- Merst Glower
2. Glober (silicone carbide)
Photomultiplier tube
Most common and most sensitive photodetector.
Nephelometry
Detects light scattered towards a detector.
