Urinalysis LAB - Exam 1 Flashcards
What are the terms that could be used to describe the color of urine specimens in our lab?
-Straw or Colorless (str)
-Yellow (yel)
-Dark Yellow (dk. yel)
-Amber or Orange
-Red or Pink
-Brown
-Green or Blue/green
What are the terms that could be used to describe clarity in our lab?
-clear (clr)
-cloudy (cldy)
-turbid
-bloody
What should not be reported on in the “other clinically signif. items?
contaminants, such as starch granules, hair, and fibers
What color is associated with the presence of Bilirubin?
Yellow orange color
What color is associated with the presence of Biliverdin?
Green
What color is associated with the presence of hemoglobin?
Amber to red color
What are two reasons that could cause cloudiness in a urine specimen that is not fresh?
-bacteria
-leukocytes
Define specific gravity of urine.
Ratio of one substance to a standard substance of the same volume. For urine, this would be the weight of a given urine volume to the same volume of water.
What is the urinary odor associated with Diabetes mellitus?
Fruity
What is the urinary odor associated with maple syrup disease?
maple syrup
What is the urinary odor associated with ingestion of asparagus, garlic, or onions?
mercapton
What is the urinary odor associated with disinfectants used to clean bedpans?
?
Define the refractive index of a solution.
measures dissolved solids and the specific gravity of urine or serum.
__________ is the pigment that gives urine it’s characteristic color.
urochrome
_________ and __________ also contribute some color to urine.
Some foods and medications can contribute to urine color as well as disease states.
Color varies with urine concentration.
urobilin, uroerythrin
Normal urine is clear.
It may become cloudy due to the precipitation of…
amorphous crystals
-amorphous phosphates =
white crystals
-amorphous urates = pink
precipitate
What can give urine a hazy appearance?
mucus
Cloudy urine may contain…
Smoky or turbid urine may contain…
leukocytes, bacteria or epithelial cells.
RBCs
Milky urine contain _____ or _____.
fat, chyle
Foam can be caused by significant amounts of ________.
protein
The ratio of the weight of urine to the weight of the same volume of distilled water at a constant temperature.
Specific gravity
This is used to measure the concentrating and diluting ability of the kidney.
Specific gravity
____________ ability is one of the first functions to be lost as a result of tubular damage.
concentrating
What is the normal specific gravity range for urine?
1.003-1.035
-true measure of specific gravity
-no longer recommended for clinical measurements
-requires temperature correction
Urinometer
-ratio is the velocity of light in air to the velocity of light in solution, using a Total Solids (TS) Meter.
-The path of light is deviated when it enters a solution, and the degree of deviation or refraction is proportional to the density of the solution.
Refractive index
The refractive index varies with…
temperature
The TS meter is temperature-compensated for temperatures between ____ F and ___F and, therefore, requires no corrections in that range.
60-100
Know the reagents for each test on the urine test strips!
!
What actually measures ionic concentration?
measures pKa change of polyelectrolytes in relation to ionic concentrations
Specific gravity reagent strips (pKa)
Specific gravity reagent strips (pKa):
When urine has an increased specific gravity, the reagent pad becomes more ________.
acidic
Urine dipstick:
what is read at 30 seconds?
Glucose- 1st
bilirubin-2nd
Urine dipstick:
What is read at 40 seconds?
Ketone
Urine dipstick:
What is read at 45 seconds?
Specific gravity
Urine dipstick:
What is read at 60 seconds?
blood-1st
pH
protein
urobilinogen
nitrite-last
Urine dipstick:
What is read at 2 minutes?
leukocytes
Color intensity usually correlates with…
specific gravity
The pigmentation urochrome is excreted in _______ amounts
constant. Regardless of diet.
What substances can cause abnormal urinary pigments?
hemoglobin, myoglobin, bile, porphyrins, melanogens, and homogenistic acid.
also many drugs and food pigments.
What information does urine odor provide in diagnosis?
It can be used to help suggest a particular syndrome, but should never be used as the only criteria in diagnosing an illness.
How does the odor of urine change after standing for some time?
sharp ammonia pungency is formed by bacterial activity
What is an ammoniacal odor associated with?
cystitis or pyelitis, usually with obstruction in the urinary tract.
Maple syrup odor is associated with…
inherited disorder of metabolism of infants
The amount of turbidity present should correlate with the number of….
microscopic elements formed
What can cause small cloudy patches in normal urine?
mucus from the urinary and genital tracts
Urates cause a _______ or ________ cloud in acid urine.
leukocytes may form a _______ cloud.
Bacteria will cause a uniform _________.
white or pink
white
opalescence
What can cause a smokiness in urine?
Red blood cells
What can cause a fluffy, bulky deposit in a urine sample?
mucin from the urinary passage in the case of increased inflammatory states of the lower urinary or genital tracts.
White and red blood cells, and epithelial cells present in sufficient numbers will cause __________.
cloudiness
How does pus appear in alkaline urine? in acidic urine?
alkaline: mucoid
acidic: crumbly
About ______ WBC/mm^2 and about ______RBC/mm^2 will produce turbidity.
200, 500
What should be done if there is any cloudiness in a urine sample?
it should be examined microscopically to identify the elements responsible for the nebulous appearance.
What is the specific gravity of water?
1.0 g/ml
When measuring specific gravity, When should you repeat the procedure by diluting the sample with an equal volume of DI water and multiply the numbers after the decimal point?
When the value falls within the range of 1.025-1.030
What conditions can cause the specific gravity to be high?
-fever
-diabetes mellitus
-acute nephritis
What conditions can the specific gravity to be low?
-chronic nephritis
-diabetes insipidus
Specific gravity varies inversely with….
and directly with…
the amount of volume
the amount of salt, urea, and protein
specific gravity ranges:
24-hour collection-
a normal random-
normally acidic urine-
24-hour collection- 1.015-1.025
a normal random- 1.003-1.030
normally acidic urine- 1.010 or higher
A low fixed urine specific gravity of 1.008-1.012 is indicative of…
chronic glomerulonephritis
A specific gravity of less than _________ is significant.
1.003
What may occur if a patient had a recent X-ray study such as IVP?
specific gravity of 1.050 with normal color
unlike the gravimetric or refractometer methods, SG measured with the chemical reagent strip method does not need to be corrected for __________ or ___________.
glucose, protein
-cloudy, turbid urine does not need to be clarified before measuring
What is the recommended method for determining SG if a urine specimen contains x-ray contrast media or plasma expanders?
the reagent strip method
_________ urine can affect the indicator system and lower the SG results on the reagent pad.
alkaline
-it is recommended that .005 be added to the SG result when the pH is alkaline. (automatic trip readers will adjust automatically for pH)
__________ strength is closely related to specific gravity.
ionic
The pH pad on the reagent strip contains what indicator dyes?
methyl red and bromothymol blue
__________protein and ___________are examples of globulin components that are sometimes present in urine, but are not distinguishable by the chemical reagent strip method for urine protein.
Bence Jones protein and mucoprotein
is based on the phenomenon called the blank (ability of protein to alter the color of some acid-base indicators without altering the pH)
“Protein Error of Indicators”
What is the confirmatory test for urine protein?
sulfosalicylic acid (SSA) precipitation test
The presence of an increased amount of ________ in a urine specimen is often the first indicator of renal disease.
protein
The amount of protein present in urine samples from patients with glomerular damage usually ranges from _________ mg/dL. If the urinary protein is due to a disorder that affects tubular reabsorption, the urine protein quantities will be much greater.
1-40
What are the two reactions that occur for glucose detection on reagent pad strips?
-glucose oxidase catalyzes the oxidation of glucose to gluconic acid and hydrogen peroxide
-Then, the peroxidase in the glucose pad catalyzes the oxidation of a chromogen by the hydrogen peroxide to form a colored product.
Reagent pad strip testing:
What temp. must glucose be analysed at?
Does glucose react with any other reducing substances? (lactose, fructose)
room temp
no
A specific gravity higher than ______ may lower glucose reagent sensitivity, especially in the presence of a high (alkaline) urine pH.
1.020
The test for ketone bodies is based on a nitroprusside reaction. ___________ acid reacts with ________________ and glycine in an alkaline medium to produce a violet-to-purple colored complex.
Acetoacetic, sodium nitroferricyanide
What can cause false-positive ketone reagent strip results?
-captopril (an antihypertensive drug)
-D-penicillamine (an antibiotic)
-Highly pigmented urine
What can cause false-negative ketone reagent strip results?
-prolonged storage at room temp (over 2 hours)
In diabetes mellitus patients, the presence of ketones in the urine (ketonuria) indicates that what should be done?
insulin dose needs to be increased
The term ___________ is used to describe the presence of intact red blood cells in the urine.
hematuria
Term used when RBCs have been destroyed, causing hemoglobin will be present in the urine
hemoglobinuria
The presence of only _____ RBCs per microliter of urine is considered to be clinically significant. For this reason, a chemical test is needed to detect quantities of blood too small to change the color of the urine.
five
What is used to differentiate between hematuria and hemoglobinuria when the chemical reagent strip is positive for blood?
Microscopic examination
What is the reagent test strip for blood based on?
he peroxidase-like activity of hemoglobin, which catalyzes the reaction of cumene hydroperoxide and 3, 3’, 5, 5’ tetramethylbenzidine.
What all is the reagent test strip for blood sensitive to?
free hemoglobin, myoglobin, and a minimum of 5 intact RBCs per microliter of urine.
What can cause a false positive for blood on the urine reagent strip?
-oxidizing agents, like bleach
- contaminated with povidone-iodine
-Microbial peroxide (from UTIs)
-myoglobin (ex: muscle wasting disease, trauma, coma)
What can cause a falsely-decreased test result for blood on reagent strip?
Captopril
What can cause a false negative for blood on reagent test strip?
not mixing urine specimen
Hemoglobinuria may be associated with:
-Hemolytic anemia
-Severe burns
-Transfusion reaction
-Infection
-Strenuous exercise
The nitrite test on the urine reagent strip detects the presence of…
nitrate-reducing bacteria (ie, gram-negative bacteria). Bladder infections are usually caused by gram-negative bacteria. These bacteria reduce nitrate to nitrite when urine remains in the bladder at least three hours.
Is nitrite present in urine in normal circumstances?
no
When present, nitrite react with __________________ in the reagent pad to produce a diazonium compound.
p-arsanilic acid
In nitrate detection on the reagent strip, is the color development proportional to the number of bacteria present?
NO
What other substances can nitrate react with in urine?
nitrite does not react with any other substances normally found in urine
Dose a negative nitrite test rule out bacterial UTI?
no. UTIs can be cause by bacteria that do not reduce nitrate.
What can cause false-positve nitrite results?
-prolonged room temp storage
-medications that cause urine to become red or orange (from incorrect reading)
What can cause false-negative result? For nitrite
-urine not remaining in the bladder long enough for bacteria to reduce nitrate
-severe bacterial infection that causes the bacteria to further reduce nitrite to nitrogen
What is the basis of the leukocyte test on the reagent strip?
-detection of esterase (granulocytic white blood cells (ie, neutrophils, basophils and eosinophils) contain) contain this)
-esterase from leukocytes react with indoxy ester derivative and diazonium salt
Is the intensity of the purple color produced on the leukocyte test proportional to the amount of leukocyte esterase present?
yes
What is the granulocyte most often detected in urine? What does it indicate?
probable urinary tract infection
_______________ do not contain leukocyte esterase and would not produce a positive leukocytes test on the reagent strip.
Lymphocytes
What should be done if leukocytes are positive on the reagent test strip?
confirm by performing a microscopic examination of the sediment
What could be a cause of a false-positive or falsely elevated leukocyte result?
vaginal contamination of the urine specimen or a highly-colored specimen.
What can cause falsely decreased results for leukocytes?
-presence of significantly elevated protein, glucose, or specific gravity (significantly elevated specific gravity can crenate the white blood cells, leaving them unable to release esterases).
-The drugs cephalexin and gentamicin
A positive leukocytes test is often accompanied by a positive __________ test. Together, they confirm the presence of a bacterial urinary tract infection.
nitrite
The presence of bilirubin in urine in detectable amounts is always…
abnormal
Even a slight change in color should be considered significant since bilirubin is never present in normal urine.
Bilirubin, a product of ____________ catabolism, is characterized by its distinctive yellow pigment
hemoglobin
Only ____________ bilirubin is excreted in urine.
conjugated
If bilirubin is elevated and is conjugated, it will be detected by the urine reagent strip.
The test for bilirubin on the urine chemical reagent strip is based on the formation of an azobilirubin compound resulting from a reaction of bilirubin in an acid medium with _______________.
diazotized 2, 4 dichloroaniline
Since other pigments in the urine may influence the test results, this test is more difficult to interpret than other urine reagent strip tests
Bilirubin
What can cause bilirubin false-positive results?
-large doses of chlorpromazine
-presence of metabolites of phenazopyridine
-Metabolites of etodolac
What can cause false negative bilirubin results?
-specimen that is not fresh
-Indoxyl sulfate (indican)
-positive nitrites
The ________ is used by some laboratories to rule out a false-positive bilirubin dipstick result that is caused by urine color interference.
Ictotest®
Bilirubin:
The Ictotest® employs the same _________ reaction as the reagent strip, but should not give a false-positive result with colored urines.
diazotization
Why will bilirubin not show on a urine test if jaundice is due to red cell destruction?
it causes unconjugated bilirubin, which the kidneys cannot excrete.
a byproduct of hemoglobin breakdown. It is produced in the intestinal tract as a result of the action of bacteria on bilirubin.
Urobilinogen
As the urobilinogen circulates in the blood to the liver, a portion of it is diverted to the kidneys and appears as urinary urobilinogen.
Which test is it impossible to get a negative result?
urobilinogen test cannot determine absences of urobilinogen
How does the test for urobilinogen work chemically?
based on the Ehrlich Aldehyde Reaction. P-dimethylaminobenzaldehyde in an acid medium with a color enhancer reacts with urobilinogen to form a pink-red color.
What can cause false positive urobilinogen test?
-porphobilinogen*
-sulfonamides
-p-aminosalicylic acid
-dugs that contain azo dyes
What can cause false-neative urobilinogen test?
-sample that remains at room temp for too long
-too much light exposure
-presence of formalin
