intro Flashcards
lab math, qc, lab safety, blood collection and spx considerations, instrumentation
error where there is continual difference between test & comparative methods values
constant error
error where difference between test & comparative method values are proportional to analyte concentration
proportional error
deterioration of reagents is a problem encountered in what phase of clinical analysis
analytical phase
ratio of warning to mandatory Westgard rules
3:3
QC chart that demonstrates the Westgard multirules
Levey-Jennings
most widely used QC chart in the clinical laboratory
Levey-Jennings
QC chart that is used to compare results of different laboratories
Youden twin plot
plot that gives the earliest indication of a trend
CuSum graph
closeness of measured values to the true value
accuracy
an ability to give repeated results on the same sample that agree with one another
precision
Scientists made same experiment with same method & specimen; all had consistent results. This is?
reproducibility (precision)
these are measures of the diagnostic accuracy of a test
sensitivity and specificity
it relates to the lowest concentration of a substance that can be detected in a test system
analytical sensitivity
the ability to detect only the chemical desired with no interference from other chemicals
analytical specificity
ability to detect the presence of disease
diagnostic sensitivity
indicate the ability of the test to generate more true (+) & few false (-) results
diagnostic sensitivity
reflects the ability of the method to detect true (-) with very few false (+)
diagnostic specificity
ability to relate results to a known reference standard through unbroken chain of comparisons
traceability
indicates the number of patients with an abnormal test result who have the disease
positive predictive value (PPV)
what is the formula for PPV?
TP / (TP + FP) * 100
indicates the number of patients with a normal test result who do not have the disease
negative predictive value (NPV)
what is the formula for NPV?
TN / (TN + FN) * 100
part(s) of descriptive statistics
central tendency, dispersion
measures of dispersion
variance, SD, CV, range
it is a percentile expression of the mean
coefficient of variation (CV)
the lower the CV, the _ the precision
higher
the average of a given set of values
mean
middle or midpoint of a distribution
median
most frequent observation in a set of data
mode
these are important criteria in evaluating instruments
sensitivity and specificity
what is a good standard curve?
- line is straight
- line connects all points
- line goes through the origin of x & y axes
there is perfect correlation of values in linear regression if value falls on _
1
it refers to any clinical lab testing done at the patient’s bedside
point-of-care-testing (POCT)
test performed usually by nonlaboratorian personnel (nurses, RTs, etc.)
POCT
nonlaboratory personnel are responsible for _% errors with regard to lab results
29%
what to do when POCT-QA issues arise?
train non-laboratory personnel
specimen used for point-of-care testing (POCT)
capillary blood
QC of POCT instruments should be done _
once each day of use
usual cause of random error in the clinical laboratory
clerical error
vapor & osmotic pressure, boiling & freezing points are examples of _
colligative properties
used to measure osmolality (2)
freezing point depression
vapor pressure depression
specimen(s) used for osmolality determination
serum or urine
how would 15.57 be rounded off to one less decimal place?
15.6
it is the relative concentration of a solution
dilution
how much diluent needs to be added to 0.2 mL of serum to make a 1:20 dilution?
3.8 mL
it is the amount of 1 substance relative to the amount of other substance in the solution
concentration
instrument that uses diffraction gratings (as commonly used monochromators)
spectrophotometer
Beer’s law mathematically establishes relationship between concentration and _
absorbance
a solution that has a transmittance of 1.0% T would have an absorbance of _
2.0 (formula: absorbance = 2 - log(%T))
formula for concentration of the unknown sample (using spectrophotometer)
(Au / As) * Cs
visible region
400-700nm
UV region
<400nm
very short wavelength
IR region
> 700nm
light source in the visible region
tungsten lamp
light sources in the UV region
Mercury arc
Deuterium
Hydrogen lamp
Xenon lamp
light sources in the IR region (2)
Merst glower
Glober (silicone carbide)
what does LASER stands for
Light Amplification by Stimulated Emission of Radiation
part of spectrophotometer that selects specific wavelength of light
monochromator
monochromator specification to measure true absorbance of compound with absorbance bandwidth of 30nm
5-nm bandpass
zeroing the spectrophotometer before testing is done usually using _
reagent blank
it is used to correct for absorbance caused by the color of reagents
reagent blank
most commonly used photodetector, and the most sensitive to low levels of light
photomultiplier tube
gold standard for drug testing
GC-MS
non-destructive technique for detecting structure of organic compound (lipoprotein particle)
Nuclear Magnetic Resonance Spectroscopy (NMRS)
effect of quenching on fluorescence
decreased
support media for zone electrophoresis include
agarose
cellulose acetate
polyacrylamide
most commonly used stain for serum protein electrophoresis
Ponceau S
a type of chemistry analyzer that uses reagents from different manufacturers / suppliers
open system analyzer
most basic or simplest pipette
Pasteur pipette (glass/plastic)
parts of positive displacement pipette (3)
piston
piston seal
capillary
glassware resistant to heat, corrosion & thermal shock
borosilicate
water that has passed through resin with charged particles is known as _
deionized water
purpose of desiccators/desiccant
absorbs moisture
in general, oxidizers should never be placed with chemicals that are _
reducing agents
laboratory hazard prevention strategies include (4)
work practice controls
engineering controls
PPE
emergency equipment
hierarchy of hazard controls (most to least effective)
elimination
substitution
engineering controls
administrative controls
PPE
equipment used to contain & expel noxious & hazardous fumes from chemical reagents
fume hood
first step in pre-analytical phase
test order
instructing the patient to undergo fasting is part of _
patient preparation
disinfectant for ethanol analysis blood collection
benzalkonium chloride
preferred site for venipuncture
antecubital veins (median > cephalic > basilic)
light source used by vein finders
infrared
most commonly used area for adult skin puncture
(2nd), 3rd & 4th finger
type of blood specimen for newborns
blood spot
ideal site of capillary blood collection in infants
medial or lateral plantar surface of the heel
shelf-life (expiration date) of an evacuated tube is defined by
vacuum retention & stability of the additive
draw volume of an evacuated tube when stored in low temperature
increased, due to decreased gas pressure inside the evacuated tube
draw volume of an evacuated tube when stored in high temperature
decreased, due to increased gas pressure inside the evacuated tube
draw volume of an evacuated tube when blood is drawn at high altitude (>5000ft)
lower
EDTA anticoagulant elevates what electrolytes
sodium & potassium
EDTA anticoagulant decreases what
calcium & iron
preferred anticoagulant for electrolyte testing
heparin
anticoagulant for lipoprotein assay and preservation
EDTA
CTAD anticoagulant is used for?
coagulation testing
temperature for lyophilization
-40°C or less
blood specimens on serum separator gel tubes must be processed within _
30 minutes
how long must a blood sample stand before being centrifuged?
30 minutes
normal color of serum
straw / pale yellow
