1030 Unit 2 Flashcards
discuss the relationship of urochrome to normal urine color
the more color intensity, the more concentrated
state how the presence of bilirubin may be suspected
will produce yellow foam when shaken
state how the presence of uroerythrin may be suspected
pink pigment in refrigerated samples
state how the presence of urobilin may be suspected
orange-brown color in old sample
state how the presence of biliverdin may be suspected
Urine will turn yellow-green when bilirubin is photo-oxidized
discuss the significance of cloudy red urine vs clear red urine
red cloudy–> RBC
red clear –> myoglobin or hemoglobin
name two pathological causes of black or brown urine
1) melanogen oxidizes to MELANIN which could come malignant melanoma
2)alkaptonuria - HOMOGENTISTIC acid is metabolite of phenylalanine seen in inborn error of metabolism (IEM)
discuss the significance of phenazopyridine in a specimen
-will interfere with chemical dipstick
-produce yellow foam
-cling to side of container
list the common terminology to report clarity
-clear–>transparent
-hazy–> few particles
-cloudy –> many particles
-turbid–> print cannot be seen through urine
-milky
describe the appearance and discuss the significance of amorphous phosphates and amorphous urates in urine that was freshly voided
-in fresh urine, amorphous phosphates and urates are present in normally small amounts
-amorphous phosphates –> react with alkaline pH urine to form white precipitate
-amorphous urates
—->have uroerythrin pigment
—->gives pink brick dust in acidic urine
—->small volumes present in urine is normal
—->adhere to urine or mucous and make diagnosis difficult but it can be separated
what are the three pathological causes of cloudy urine?
-RBC
-WBC
-bacteria
what are the five non-pathological causes of cloudy urine?
-crystals
-semen, mucous
-fecal contamination
-radiographic contrast media
-talcum powder, vaginal creams
define specific gravity and tell why this measurement can be significant in routine analysis?
-density of solution (urine) compared with the density of a similar volume of water (one drop)
-influenced by size and amount of particles. Can detect concentration not seen by the naked eye. heavy concentration can indicate abnormalities
describe principle of refractometer
determines the concentration of particles by measuring refract.
describe the principle of reagent strip
based on change in pKa of a polyelectrolyte in an alkaline medium
describe the principle of osmolarity
expression of the concentration of dissolved particles (solute) in a specific amount of solution (solvent)
Given concentration of glucose and protein in a specimen, calculate the correction needed to compensate for these high molecular weight substances in the refractometer reading of specific gravity
-subtract 0.003 for each gram of protein present
-subtract 0.004 for each gram of glucose present
example: specimen containing 1 g/dl protein and 1 g/dl glucose present. Specific gravity of glucose is 1.030
1.030 - 0.003 (protein) = 1.027
1.027 - 0.004 (glucose) = 1.023 corrected specific gravity
Name two nonpathological causes of abnormally high readings of specific gravity using a refractometer
1) Radiographic contrast media (IVP)
2) Dextran, other IV plasma expanders
describe the advantages of measuring specific gravity using a reagent strip and osmolarity
not affected by high-molecular weight substances
what odor would be present in a specimen with bacterial decomposition (UTI)?
foul, ammonia
what odor would be present in a specimen with ketones?
fruity, sweet
what odor would be present in a specimen with maple syrup disease?
maple syrup
what odor would be present in a specimen that is phenylketonuria ?
mousy
what odor would be present in a specimen that is tyrosinemia?
rancid
what odor would be present in a specimen that is isovaleric acidemia?
sweaty feet
what odor would be present in a specimen that is methionine malabsorption?
cabbage
what odor would be present in a specimen that is contaminated?
bleach
the concentration of a normal urine specimen can be estimated by what?
color
The normal yellow color of urine is produced by?
urochrome
the presence of bilirubin in a urine specimen procedures as:
yellow foam after being shaken
the urine specimen containing melanin will appear?
black
specimen that contain hemoglobin can be visually distinguished from those that contain RBCs because..
RBCs produce a cloudy red specimen
a patient with a viscous orange specimen may have been:
treated for UTI
The presence of a pink precipitate in a refrigerated specimen is caused by..
uroerythrin
microscopic examination of a clear urine that produces a white precipitate after refrigeration will show..
amorphous phosphate
the color of urine containing porphyrins will be..
port wine
what would be a specific gravity of a pale yellow urine?
1.005
a urine specific gravity measured by a refractometer is 1.029 and the temperature of the urine is 14 C. The specific gravity should be reported as
1.029
The principle of refractive index is to compare:
light velocity in air with light velocity in solutions
a correlation exist between a specific gravity by refractometer of 1.050 and a:
radiographic dye infusion
a cloudy urine specimen turns black upon standing and has a specific gravity of 1.012 the major concern about this specimen would be:
color
a specimen with a specific gravity of 1.035 would be considered:
hypersthenuric
a specimen will a specific gravity of 1.001 would be considered:
not urine
a strong odor of ammonia in urine specimen would indicate:
an old specimen
the microscopic examination of a clear red urine in reported as many WBCs and epithelial cells. What does this suggest?
possible mix up of specimen and sediment
which of the following would contribute the most to a urine osmolarity?
A. one osmole of glucose
B. one osmole of urea
C. one osmole of sodium chloride
D. all contribute equally
C. one osmole of sodium chloride
The boiling point is _____ by solute
raised
the vapor pressure is ______ by solute
lowered
the osmotic pressure is _____ by solute
raised
what does an osmole contain?
one gram molecular weight of solute dissolved in 1 kg of solvent
the unit of osmolarity measured in the clinical laboratory is the …
osmole
in the reagent strip for specific gravity reaction..
release hydrogen ions in response to ion concentration
what will react in the reagent strip specific gravity?
chloride
what are the steps for performing reagent strip testing?
1) Dip strip in to well-mixed urine at room temperature
2) Remove excess urine by touching edge to the container as the strip is removed
3) Blot the edge of strip on absorbent pad
4) Wait for specific time to read (time is critical)
5) Read using good light, report results
what are four causes of premature deterioration of reagent of strips and describe how to avoid to form?
-moisture
-volatile chemicals
-heat
-light
- keep lid on as much as possible
list 5 quality control procedures routinely performed with reagent strip testing
1) test open bottle of reagent strips with known positive and negative controls per facility protocol
2) Resolve control results that are out of range by further testing
3) Test reagents used in confirmatory tests with positive and negative control
4) Perform positive and negative controls on new reagents and newly opened bottles of reagent strips
5) Record all control results and reagent lots number
list the reasons for measuring urinary pH, and discuss their clinical applications
- helps determining acid-base disorders of metabolic or respiratory origin
-help in management in urinary conditions that require the urine to maintain a specific pH
-the inorganic chemicals dissolve in the urine and can form crystals which can become renal calculi
-an acidic urine can aid in treating UTI
discuss principle of pH testing by reagent strip
-strip read in increments 0.5 or 1 ranging between 5 to 8.5 or 9
-both manufacturers use a double indicator
—>methyl red -> red to yellow (pH 4 to 6)
—>bromothymol blue -> yellow to blue (pH 6 to 9)
Describe and discuss prerenal proteinuria
-proteins that come from the plasma before it gets to kidneys
-condition may be short term
-if proteins are high, will reabsorb and overflow into urine
-increase of protein (Bence Jones protein) in plasma is multiple myeloma
-increase in antibody light chains
-examples: hemoglobin,. myoglobin, acute phase reactants due to infection and inflammation
-to diagnose: need to have serum protein electrophoresis and immunoelectrophoresis
Describe and discuss tubular dysfunction in Renal proteinuria
-tubular reabsorption problems are caused by increase of albumin
-other low molecular weight particles that are normally reabsorbed end up being excreted through urine
- Caused by:
—->exposure to toxic substances
—->heavy metal
—->severe viral infections
—->Fanconi syndrome
-tubular damage results in low levels of proteins excreted
Describe and discuss glomerular dysfunction of Renal proteinuria
-glomerular membrane is damaged/not filtering properly
—->allow serum proteins through
—->leads to excretion of RBC and WBC
—->Amyloid material = toxic substances, immune complexes (IgA, IgG, antibodies)
—-> increased pressure caused increased amount of albumin to enter filtrate
- glomerular damage = 4 g/dl daily of protein excretion
-may be reversible in hypertension, strenuous exercise, dehydration, and pregnancy (preeclampsia)
Discuss and describe postural proteinuria
- seen after periods of staying in a vertical position and then disappears after being in a horizontal position
-Caused by: increased pressure on the renal vein when in vertical position
-patients instructed to collect orthostatic urine
-protein can be added to urine after kidney from any of the structures of the lower urinary tract (urethra, bladder, ureters, prostate, vagina )
-proteins can also be found with/in:
—-> bacterial/fungal infections
—->inflammation
—->blood from injury or menstruations
—->prostatic fluid
What are the steps of collecting an orthostatic urine and explain
1) empty bladder before bed
2) collect 1st sample after being in horizontal position
3) collect 2nd sample after being vertical position
-results : 1st–>negative; 2nd –> positive
explain “protein error of indicators”
-color change is in response to pH
- certain indicators change in presence of protein even in pH is constant
-Reason: because albumin accepts hydrogen ions
-sensitive to albumin because there are more amino groups to accept H+
What are some sources of interference that can occur during “error protein indicator” method?
-Major reason: highly alkaline urine overriding the acid system. Rise in pH w/o protein presence
-leaving reagent pad in urine too long
-false positive
—-> pigmented urine
—->container having ammonium compound detergents, antiseptics
—-> blood may result in high proteins
Discus microalbuminuria
-abnormally increased excretion rate of albumin in the urine in the range of 30-299 mg/g creatinine
-semiquantitative strips for patient at risk of renal failure. 1st morning specimen recommended
-tests that measure of albumin and/or creatinine = micral test and immunodip
Describe the Micral test
-gold labeled
-antihuman albumin antibody-enzyme conjugate
-albumin binds to antibody (Alb-AB)
- color reaction is white to red
-results range from 1-10 mg/dL
Describe immunodip
-immunochromographic technique
-special designed container is placed in the urine for 3 minutes
-it can measure bound and unbound, they migrate up the strip, color intensity of bans is compared to a chart
explain why glucose that is normally reabsorbed in the proximal convoluted tubule may appear in the urine and state the renal threshold levels for glucose?
-if glucose exceeds renal threshold which is 160-180 mg/dL, it will spill over into urine
What are possible interferences in the glucose oxidase method of reagent strip testing
-False positive –> contaminated w/ peroxidase or strong oxidizing detergents
-False negative
—->strong reducing agents = Ascorbic acid (vitamin C)
—-> high levels of ketones
—-> high specific gravity and low temperature
—-> unpreserved urine increase bacteria cause a decrease in glucose
Describe principle of glucose oxidase method of reagent strip testing for glucose
-glucose oxidase –> specificity looks for glucose (no other sugars)
-2 step process v glucose oxidase
—-1) glucose + O2 —-> gluconic + H2O2
—-2) H2O2 + chromogen —-> oxidized
^Peroxidase
-color is proportional to concentration
Describe copper reduction method for the detection of urinary-reducing substances and discuss current use of this procedure
-cupric sulfide reduce to cuprous oxide resulting in a color change
v Heat
CuSO4 + reducing substance ——> Cu2O + oxidized substance = color
-color change from blue -> green -> yellow -> orange/red -> brown
-used for detecting reducing sugars in infants.
What are the 3 ketone bodies that appear in urine
1) Beta-hydroxybutyrate (78%)
2) Acetoacetic acid (20%)
3) Acetone (2%)