Quiz 1 - BFA Lab

quality assurance

quality patient care backed by written documentation

3 phases: pre-analytical, analytical, and post-analytical

Pre-Analytical Phase

“Before analysis”

-specimen collection and handling

-patient prep (fasting, medication)

-type of specimen and volume

-Sterile? Preserved?

Analytical Phase

“During analysis”

-reagents, supplies, instrumentation

-QC monitoring, lab personnel technical skills

-Dating reagents (recieved/prepared/opened/expired)

-Check reagents w/ ± controls

What should be labeled when dating reagents?

-opened date + your initials (if you’re the first one opening it)

-expiration date

What are important elements of quality control samples?

-usually the same matrix as patient samples

-solution previously tested more than 40x to achieve acceptable target range of values for a certain method

-QC is used to measure analytical error present in a method → always done before testing any patient samples (QC must be in acceptable range b4 testing patients)

what kind of error does quality control measure?

analytical error present in a method

-always done b4 testing patient samples→ QC must be w/i acceptable range b4 testing patients

Post-analytical

“After Analysis”

-document results using units, significant figures, etc.

-Critical value: significantly abnormal results that indicate life-threatening condition (requiring immediate physician attention)

-Communicate results to health care provider through HIPPA-approved, secured methods

critical value

significantly abnormal results that indicate life-threatening condition (requiring immediate physician attention)

how should specimens be labeled in the lab?

always on the tube or container w/ 2 patient identifiers

—never label just the lid

how can corrections be made in lab documents?

always one line through, initial and date

-never scribble

-always pen, never pencil

-no white-out or erasable pens

refractometer

used to measure specific gravity in urine samples; measures concentration of dissolved chemicals in urine; no units

-sp grav. measurements used as an indicator of kidney health

-normal reference range: 1.005 to 1.030

what does specific gravity of urine indicate?

concentration of dissolved chemicals in urine; no units

used an as indicator of kidney health

what is the normal reference range of sp. grav. in urine?

1.001/1.005 to 1.035

what are reasons that sp. grav. of urine might be low?

diabetes, overhydration, hypertension

what are reasons that sp. grav. of urine might be high?

dehydration, UTI, heart failure

what is the sp. grav. of water?

always 1.000

what can values greater than 1.035 indicate for sp. grav using the refractometer?

a recent intravenous pyelogram or infusion of a high molecular weight substance, like dextran, with the excretion of the material

—for such patients sp. grav. can be obtained by a reagent strip method w/o interference

what is high specific gravity of urine called?

hypersthenuria

what is low specific gravity of urine called?

hyposthenuria

what is specific gravity of urine matching that of plasma all of the time?

1.010 = isothenuria = renal failure

what are limitations of using the refractometer to measure the sp. grav. of urine?

specimens w/ sp. grav greater than 1.050 should be diluted and retested

-only the decimal portion of the observed diluted sp. grav. is multiplied by the dilution factor

what are the potential color descriptors of urine?

straw (very pale yellow)

yellow

amber (dark yellow)

brown

black

red

orange

-note: clear is not a color

what appearances can urine be described as having?

clear (no discernible cloudiness)

hazy (print easily read through the solution, but it is not crystal clear)

cloudy (print is difficult or impossible to read through the solution)

what is the possible clinical significance of yellow & cloudy urine?

UTI, yeast infection, pyuria

what is the possible clinical significance of foamy & amber urine?

nephrotic syndrome, proteinuria

what is the possible clinical significance of red & bloody urine?

called hematuria; kidney stones, glomerulonephritis, kidney inury

what is the possible clinical significance of bright orange urine?

caused by drug called Pyridium

what is the possible clinical significance urine turning port wine colored after it has been standing?

may contain porphyrins

what are the ten things that Multistix 10G test for?

Specifc gravity, pH, protein, glucose, ketone, bilirubin, blood, urobilinogen, nitrite, leukocytes

principle of specific gravity on multistix

based on the pKa change of certain pretreated polyelectrolytes in relation to ionic concentrations

in presence of an indicator, colors range from deep blue-green (low ionic conc.) thru green and yellow-green w/ increasing ionic concentrations

principle of pH test on multistixs

uses two indicators (methyl red and bromthymol blue) which give a broad range of colors covering the entire urinary pH range

colors range from orange, yellow, green, to blue

principle of protein test on multistix

based on the protein-error-of-indicators principle

at a constant buffered pH, tetrabromphenol blue will be yellow

Any green color development= protein

principle of glucose test on multistix

uses the enzyme glucose oxidase to catalyze the formation of gluconic acid and hydrogen peroxide from the oxidation of glucose

a second enzyme, peroxidase, will then catalyze the rxn of hydrogen peroxide w/ potassium iodide chromagen, oxidizing the chromagen to shades of green to brown

principle of ketone test on multistix

nitroprusside will react with acetoacetic acid or acetone to form a purple chromagen. Glycine is present as a nitrogen source for the rxn, which occurs at a strongly alkaline pH

principle of bilirubin test on multistix

bilirubin in urine will couple with diazotized dichloroaniline in a strong acid medium to form compounds which are various shades of tan

principle of blood test on multistix

hemoglobin in blood has peroxidase-like activity, which catalyzes the rxn of diisopropylbenzene dihydroperoxide and tetramethylbenzidine

resulting colors range from orange to green-blue

principle of urobilinogen test on multistix

modified Ehrlich reaction, in which dimethylaminobenzaldehyde reacts with urobilinogen at acid pH to produce a pink-red color

principle of nitrite test on multistix

at an acidic pH, nitrite in the urine reacts w/ p-arsanilic acid to form a diazonium compound, which, in turn, couples w/ tetrahydrobenzo-quinolin-3-ol to produce a pink color

principle of leukocyte test on multistix

some WBCs associated w/ bacterial infections contain esterases that catalyze the hydrolysis of a pyrrole amino acid ester to liberate 3-hydroxy-5-phenyl pyrrole

pyrrole reacts with diazonium salt to give a purple product

what are the range of specific gravity readings using the multistix for random urines and first morning specimens?

Random: 1.001-1.035

1st morning: >1.010

what are the normal/abnormal ranges of pH readings using the multistix for urine?

normal and abnormal readings range from 4-8

physiologically impossible to have a reading outside of this range

what are the normal/abnormal ranges of protein readings using the multistix for urine?

normally, none should be present, although there is a minute amount excreted by the normal kidney

“Trace” may not be significant

Values above “trace” indicate significant proteinuria

what are the normal/abnormal ranges of glucose readings using the multistix for urine?

normally, no detectable amount present

concentrations as small as 0.1 g/dL may be significantly abnormal if found consistently

what are the normal/abnormal ranges of ketone readings using the multistix for urine?

normally, none are present

in starvation diets, or in other abnormal carbohydrate metabolism situations, ketones appear in the urine in excessively large amounts before serum ketones elevated

a positive urine glucose and ketone on the same urine require immediate notification of the physician

what are the normal/abnormal ranges of bilirubin readings using the multistix for urine?

normally, none is detectable in urine

Even trace amounts are sufficiently abnormal to require further investigation

atypical colors may indicate that bilirubin-derived bile pigments are present and are possibly masking the bilirubin rxn → follow up is required in this case

what are the normal/abnormal ranges of blood readings using the multistix for urine?

normally, none is found in urine

frequently found in the urine of menstruating females

what are the normal/abnormal ranges of urobilinogen readings using the multistix for urine?

normal values range from 0.1-1.0 mg/dL

—NOT POSSIBLE to report out “negative” for this test

what should not be present in normal patient urine?

protein, glucose, ketones, bilirubin, blood, nitrite, or leukocytes

what are the normal/abnormal ranges of nitrite readings using the multistix for urine?

normally, none is present in urine

positive in cases of significant infection depends on how long the urine specimen was retained in the bladder prior to collection

what are the normal/abnormal ranges of leukocyte readings using the multistix for urine?

normal urine specimens yield negative results

positive results (>small) are clinically significant

trace results observed repeatedly may be clinically significant

what are general limitations of the Multistix 10SG?

substances producing abnormal urine colors may also affect the readability of the strips. Deterioration of the strips themselves can be noted as tan-to-brown discoloration of all reagent areas

what are some limitations to the glucose test on the multistix?

Ascorbic acid (vit. C) levels greater than/equal to 50 mg/dL may cause false negatives

reactivity of the test decreases as sp. grav. increases

some oxidizing contaminants (hypochlorite) and microbial peroxidase may produce false positives

Test is sensitive to greater than/equal to 75 mg/dL

what are some limitations to the bilirubin test on the multistix?

ascorbic acid greater than/equal to 25 mg/dL may cause false negatives

sensitivity is greater than/equal to 0.4 mg/dL

when very small amounts sought to be found in urine, Ictotest is test of choice

what are some limitations to the ketone test on the multistix?

no reaction with beta-hydroxybutyric acid

sensitivity is greater than/equal to 5 mg/dL acetoacetic acid

what are some limitations to the blood test on the multistix?

more sensitive to free hemoglobin and myoglobin than to intact RBCs.

sensitivity is ~5-15 intact rbc/hpf

“small”= ~15-20 rbc/hpf

“moderate”= ~20-50 rbc/hpf

“large”= >50 rbc/hpf

what are some limitations to the pH test on the multistix?

readings are not affected by variations in urinary buffer concentration

If excess urine remains on strip, runover from the protein area may occur, causing a falsely lowered pH result

what are some limitations to the protein test on the multistix?

reagent area is more sensitive to albumin than to globulins, hemoglobin, Bence-Jones protein and mucoprotein

negative result does not rule out these other proteins

highly buffered alkaline urines may overcome the buffering capacity of the reagent and give a false positive

sensitivity is greater than/equal to 15 mg/dL albumin

what are some limitations to the urobilinogen test on the multistix?

result of “negative” NOT possible

falsely decreased results may be obtained if formalin present or if light exposure occurs

strip reactivity increases with temperature

sensitivity is greater than/equal to 0.2 mg/dL

what are some limitations to the nitrite test on the multistix?

test is specific for nitrite and will not react with any other substance normally excreted in urine

uniform pink color = positive, but pink spots/edges should be ignored

false negatives may result if the organism can’t convert nitrate to nitrite, if bladder retention of urine is less than 4 hours, or if dietary nitrate is absent

sensitivity= greater than/equal to .06 mg/dL nitrite ion (greater than/equal to 100,000 organisms/ mL)

what are some limitations to the leukocyte test on the multistix?

glucose levels greater than/equal to 3 g/dL or high sp. grav. may decrease results

some antibiotics (tetracycline) may cause false negatives

sensitivity is ~3-10 cells/hpf

“small”= ~10-20 wbc/hpf

“moderate”= ~20-50 wbc/hpf

“large”= >50 wbc/hpf

what does the clinitest test for?

reducing substances using a reagent tablet

what is the clinitest typically used for?

screening for galactosemia in pediatric urines

-positive reaction with negative glucose on reagent strip may indicate the presence of other reducing substances (lactose, fructose, galactose, and pentose)

what kind of reaction does the clinitest utilize?

classic Benedict’s copper reduction reaction

-copper sulfate reacts with reducing substances in the urine

what specimen should be used for the clinitest?

random, freshly voided urine; refrigerate urine if test can’t be performed w/i one hour of collection; test for reducing substances

what are interpretations of the clinitest?

normal urine will not have detectable reducing substances

Positive rxn w/ negative glucose on reagent strip may indicate the presence of other reducing substances (lactose, fructose, galactose, pentose)

Sensitivity = greater than/equal to 0.25 g/dL (0.25%)

If color is between two, call it the lower value

Test is currently clinically used to fulfill state law regarding screening for children between birth and 3 years for galactosemia/galactosuria

what are limitations of the clinitest

only for reducing substances

what does the ictotest test for?

amount of bilirubin in urine using a reagent tablet

what is the Ictotest based on?

the coupling of 2, 4-dichlorobenzene diazonium tetrachlorozincate with bilirubin in an acid medium to give a blue/purple reaction product

what specimen should the Ictotest be performed on?

random, freshly voided urine

refrigerate sample if testing can’t be done w/i one hour of collection

sample should be protected from light since bilirubin is destroyed by ambient. light

what are interpretations of the Ictotest?

bilirubin is not normally present in urine concentrations sufficient to give a pos. result w/ this test

presence of blue/purple color on the mat indicates bilirubin is present; slight pink/red color should be ignored

Intensity of color is proportional to the amount of bilirubin present

sensitivity = greater than/equal to 0.05 mg/dL bilirubin

—more sensitive than the multistix method

what are limitations for the Ictotest?

specific for bilirubin

deterioration of the tablet will be indicated by tan-to-brown discoloration

what does the Acetest test for?

the presence of ketones using a reagent tablet

how does the Acetest work?

Nitroprusside will react with ketone bodies to give a purple color

what specimen should be used for the Acetest?

random, freshly voided urine

refrigerate if testing can’t be done w/i one hour after collection

tests for ketones

what are interpretations of the Acetest

ketones are not normally found in urine under normal conditions of carbohydrate metabolism

purple color on the tablet is recorded as small, moderate, or large after comparison with color chart

tablet is most sensitive to acetoacetic acid, less sensitive to acetone, and will not react with beta-hydroxybutyric acid

sensitivity is greater than/equal to 5 mg/dL acetoacetic acid

what are limitations of the Acetest?

absorption of the urine into tablet should take less than 30s; if more than 30s required, tablets have been exposed to moisture and may not give valid results

presence of hydroxyquinoline may give false positives

—this tablet can also be used to test for ketones in serum, plasma, and whole blood, using the same color comparison chart

what does the Sulfosalicylic acid (SSA) test test for?

amount of protein present (more turbidity= more protein)

what is the principle of the SSA test?

sulfosalicylic acid and urine are mixed in equal proportions, with pH about 4-5

protein cations react with the sulfosalicylic acid anions to form an insoluble complex

turbidity produced is proportional to the amount of protein present

what specimen should be used for the SSA test?

random, freshly voided urine

cloudy urines should be centrifuged, and the clear supernatant used for the test

what are interpretations of the SSA test?

normally no detectable amount of protein present in urine

proteinuria > 10 mg/dL may be clinically significant if consistently present

proteinuria > 30 mg/dL is always clinically significant

Sensitivity= 10-20 mg/dL (“trace”)

what are limitations of the SSA test?

cloudiness due to urate crystals will disappear when the tube is warmed moderately

SSA will also precipitate mucus and X-ray contrast media

what are limitations to the sp. grav. reading on the multistix?

reading correlates w/i .005 w/ refractometer result. For increased accuracy, add .005 to readings from urines w/ pH higher than 6.5

what is the principle that the refractometer is based on?

concentration of solute in solution is proportional to the refractive index of the solution

refractive index= comparing velocity of light in air to velocity of light in solution (dependent on concentration of dissolved solute in solution→ determines angle light passes thru)

cellular elements don’t contribute to specific gravity→ refractive index of cellular elements similar to water