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MLSCI 262 > 360 - Urinalysis > Flashcards

360 - Urinalysis Flashcards

1
Q

types of urine collection techniques

A

routine void/random
midstream
catheter
suprapubic aspiration
pediatric

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2
Q

Why is the first-morning urine the recommended specimen for urinalysis

A

it’s the most concentrated
- can be a clean catch or midstream

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3
Q

catheter urine

A
  • often contaminated with CNS
  • insertion of thin rubber tube through urethra into bladder
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4
Q

suprapubic aspiration

A

usually infants for culture
needle inserted directly into bladder guided via ultrasound; urine drained

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5
Q

random urine specimens - acceptable for urinalysis?

A

acceptable for urinalysis but if urine has NOT been in bladder for four hours, urine nitrite may be undetectable

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6
Q

when should urinalysis be processed?

A

within 2 hours of collection as many physical characteristics unstable = bilirubin, urobilinogen, pH

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7
Q

which microscopic elements are unstable

A

cells and casts degrade upon storage while bacteria and yeast can multiply

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8
Q

how can we preserve urines

A

refrigeration
cold temps inhibit bacterial growth BUT promote crystal formation
APL does not accept urine specimens greater than 24h old

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9
Q

three general components of routine urinalysis

A

physical
chemical
microscopic

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10
Q

components of physical examination

A
  • clarity: look down and sides of tube (clear, hazy [bottom not clear], cloudy, turbid)
  • colour
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11
Q

T or F. Most urines are clear when voided and cloudiness occurs upon standing

A

T!
amorphous urates may precipitate in acidic urine
amorphous phosphates may precipitate in alkaline urine
LOTS of blood cells = cloudiness too

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12
Q

what is urine colour affected by?

A

concentration of sample
presence of excreted metabolites
medications
other chemicals
cellular content

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13
Q

normal urine colour

A

varies from pale yellow to dark amber

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14
Q

possible pathological cause of AMBER urine

A

bilirubin

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15
Q

possible no-pathological cause of AMBER urine

A

dehydration

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16
Q

which urine components are light sensitive

A

bilirubin
urobilinogen
porphyrins

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17
Q

possible pathological cause of ORANGE urine

A

bilirubin

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18
Q

possible non-pathological cause of ORANGE urine

A

carrots
riboflavin (vit B)
rhubarb

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19
Q

possible pathological cause of PINK to RED urine

A

red blood cells (CLOUDY)
hemoglobin (CLEAR)
myoglobin
porphyrins

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20
Q

possible non-pathological cause of PINK to RED urine

A

beets
methyldopa
Senna (laxative)

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21
Q

possible pathological cause of RED to BROWN urine

A

prophobilin

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22
Q

possible pathological cause of BROWN to BLACK urine

A

bilirubin
melanin
methemoglobin
myoglobin

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23
Q

possible non-pathological cause of BROWN to BLACK urine

A

iron compounds
levodopa (Parkinson’s)
quinine (Malaria)

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24
Q

possible pathological cause of BLUE to GREEN urine

A

Pseudomonas
biliverdin

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25
Q

possible non-pathological cause of BLUE to GREEN urine

A

methylene blue

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26
Q

how can colorimetric changes on urine regent pads be detected

A

manually or reflectance spec

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27
Q

prior to testing urine chemically, what must we do before using the strips

A

visually check them
- can change colour from moisture (especially NIT)

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28
Q

pH of normal urine

A

4.5 to 8.0, depending on amount of acid or vase excreted
physiologically impossible to go above or beyond (>8.0 = bacteria; <4.5 = adulteration)

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29
Q

what principle is the pH test based on

A

a double indicator system = bromothymol blue and methyl red
protons in urine react w anionic indicator dye to reduce the indicator dye and cause a colour change

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30
Q

false acidity of urine

A

excess urine on reagent pad can wash protein reagent pad buffer onto pH = falsely decreasing pH

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31
Q

if kidney function is normal, urine is acidic in …

A

resp and metabolic acidosis

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32
Q

T or F. All WBCs produce leukocyte esterase

A

F!

All but lymphocytes

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33
Q

how does the leukocyte reagent pad work?

A

granulocytic leukocytes hydrolyze an ester in test pad to produce aromatic compound and an acid

aromatic compound reacts with a diazonium salt to produce azo dye

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34
Q

false pos in leukocyte biochemical test

A
  • colour maskers (beets, nitrofurantoin)
  • contamination of collection container with an ox agent
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35
Q

false neg of leukocyte biochemical test

A
  • protein >5g/L
  • glucose >30 g/L
  • ascorbic acid
  • high SG
  • cephalexin, cephalothin, gentamicin, tetracycline
  • leukocytes settling to bottom (MIX PROPERLY)
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36
Q

clinical significance of leukocyturia

A

infections and inflammatory diseases such as UTIs and pyelonephritis

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37
Q

T or F. Nitrites are not found in normal urine

A

T!

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38
Q

Reaction in nitrites biochemical test pad

A

Greiss reaction - at an acidic pH, nitrite (after bacteria reduced nitrate) in the urine react w aromatic amine to form diazonium compound
- diazonium compound + aromatic compound = pink

NOTE: colour development is not proportional to number of bacteria present

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39
Q

urine nitrite indicates

A
  • presence of bacterua
  • may aid in diagnosis of asymptomatic cystitis
  • evaluation of antibiotic treatment
  • screening of urine for culture
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40
Q

T or F. Protein is not normally detected in urine

A

T!
healthy adults excrete less than 0.15g of protein per day and urine reagent strip usually do not detect this amount

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41
Q

The ability to detect bacteria using nitrite is dependent on: (3)

A
  • bacteria’s ability to reduce nitrate to nitrite
  • enough nitrate substance (diet)
  • urine must be held in bladder for 4 hrs (first morning urine!)
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42
Q

first sign of glomerular damage

A

albumin in the urine

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43
Q

reaction for urine protein

A
  • principle of protein error of indicators
  • buffered pH of 3.00, colour of indicator is yellow
  • indicator dyes release protons in response to proteins (ALBUMIN) which are anionic = indicator changes colour
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44
Q

false pos for proteins

A
  • highly buffered alkaline urines
  • high SG
  • pigmented urines
  • prolonged dipping of regent strip may remove buffer
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45
Q

false neg for proteins

A

negative result does not rule out presence of uromodulin, and globulin proteins (hemoglobin, myoglobin, monoclonal free lt chains)

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46
Q

clinical significance of proteins in the urine

A

persistent detectable proteinuria is associated w renal diseases such as glomerulonephritis and nephrotic syndrome

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47
Q

pre-renal proteinuria

A
  • overflow proteinuria caused by increase in low MW plasma proteins
  • these proteins pass through healthy glomeruli but increased concentration = exceeds the reabsorption capability of tubules
  • low MW proteins may be APRs (Hb, Mb) or abnormal proteins such as monoclonal free light chains
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48
Q

renal proteinuria (glomerular leakage)

A
  • selective: the slits between glomerular membrane podocytes are still intact but are wider than usual; large molecules such as albumin pass through and are excreted
  • non-selective: proteins of any size can pass through the damaged glomerulus
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49
Q

tubular proteinuria

A

glomeruli are healthy but tubules cannot reabsorb low MW proteins such as B2-microglobulin and Ig; rare and may be caused by heavy metal poisoning and nephrotoxic drugs

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50
Q

post-renal proteinuria

A

proteins found in urine originate from urinary tract as a result of inflammation, malignancy, or injury
uromodulin is produced by renal tubular epithelial cells in loop of Henle and is always present in urine

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51
Q

T or F. Glucose is not found in normal urine

A

T!

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52
Q

T or F. Glucose is a semi-quantitative test

A

T!
one enzyme, glucose oxidase, catalyzes oxidation of glucose to form gluconic acid and H2O2

second enzyme = peroxidase, oxidizes chromogen by hydrogen peroxide

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53
Q

false pos for glucose

A

oxidizing agent and peroxide contamination can cause false positive

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54
Q

false negative for glucose

A
  • sensitivity decreased by high SG or low temp
  • high ketones may cause neg interference
  • high concentrations of ascorbic acid
  • bacterial glycolysis may decrease glucose results
55
Q

clinical significance of glucose in the urine

A
  • when blood glucose exceed renal threshold (11 mol/L)
  • glycosuria most commonly associated w uncontrolled DM, advanced renal disease, and pregnancy
56
Q

ketones in urine

A

produced in the liver during metabolism of fatty acids; urine strip only detects acetoacetic acid

57
Q

nitroprusside

A

acetoacetic acid reacts with this to develop colour

acetone does not react unless glycine is added to pad

58
Q

false pos for ketones

A

colour maskers
large amounts od levodopa metabolites or with compounds containing sulfhydryl groups (EX: MESNA and captopril)

59
Q

false neg for ketones

A

under improper storage conditions, acetoacetic acid can be broken down by bacteria

60
Q

clinical significance of ketones in urine

A

type I diabetics monitor insulin dosage

ketonuria combined with glycosuria indicates uncontrolled DM1

ketonuria is found in some inherited metabolic disorders (phenylketonuria)

times of physical stress = starvation, fasting, pregnancy, exercise, dehydration, vomiting

61
Q

reaction of blood on urine pad

A

based on peroxidase-like activity of Hb, which catalyzes rxn of cellular peroxide and a chromogen

detects intact RBCs and free Hb

sensitivity of approximately five red blood cells/uL

62
Q

false pos for blood

A
  • presence of oxidizing contaminants in container (bleach)
  • microbial peroxidase associated with UTI (E. coli)
  • menstrual contam
  • test strip equally sensitive to myoglobin as Hb
63
Q

false neg for blood

A
  • elevated SG
  • erythrocytes will settle at bottom; MIX PROPERLY!
  • high nitrite
64
Q

most common cause of hematuria

A

renal calculi
glomerulonephritis
pyelonephritis

65
Q

Transient hematuria can result from …

A

strenuous exercise

66
Q

hemoglobinuria

A
  • occurs when amount of free hemoglobin exceeds binding capacity of haptoglobin
  • hemoglobinuria observed in intravascular hemolysis, trxns, severe burns and infections
67
Q

myoglobinuria

A

rhabdomyolysis, trauma, crush injuries
toxic to nephron tubules and may cause acute renal failure

68
Q

T or F. Urobilinogen is normally found in urine and give urine its characteristic colour

A

T! it is a water-sol degradation product of bilirubin

69
Q

urobilinogen test rxn

A

Ehrlich rxn
- acid medium = p-dimethylaminobenzaldehyde + colour enhancer reacts with urobilinogen to produce pink colour

70
Q

false positive for urobilinogen

A

colour maskers
porphobilinogen

71
Q

false negative for urobilinogen

A

degraded by acidic urine, light, and storage at room temp

72
Q

clinical significance of urobilinogen

A

increased amounts observed in hepatic disorders and hemolytic disorders

73
Q

T or F. Bilirubin is a normal constituent of urine

A

F! it is not; conjugated, water-sol bilirubin can be found in urine

74
Q

false pos for bilirubin

A

colour maskers

75
Q

false neg for bilirubin

A

photo-labile and temp sensitive
high concentrations of ascorbic acid and nitrite may cause negative interference

76
Q

clinical significance of bilirubin in the urine

A
  • early indicator of liver disease = hepatitis cirrhosis
  • also associated with bile duct obstruction: gallstones, tumors
  • increased erythrocyte destruction does not produce bilirubinuria
77
Q

the density of a solution compared to the density to an equal volume of deionized water at the same temperature

A

specific gravity

78
Q

this affects SG

A

solute number and mass

79
Q

the SG of normal urine

A

1.005 to 1.030

80
Q

reaction of S on urine test pad

A
  • test pad = polyelectrolyte and pH indicator maintained at alkaline pH
  • ionic solutes in urine cause protos to be released from polyelectrolyte pad
  • release of protons from pad cause surrounding pH to decrease and bromothymol blue changes to yellow-green
81
Q

false pos for SG

A

high proteins

82
Q

false neg for SG

A

highly buffered alkaline urines
add 0.005 to SG if pH is >/=6.5 when reading

83
Q

clinical significance of SG

A
  • can be used to monitor pt hydration & ability of kidney to concentrate urine
  • SG of 1.000 = specimen adulteration
  • SG will increase with high ketones
84
Q

what is the refractive index of a solution dependent on

A

wavelength of light used
temp of solution
concentration of solutes in solution

85
Q

refractometer and SG

A

measures SG indirectly by comparing the refative index of light in the air (1.000) to urine

86
Q

how are refractometers calibrated?

A

using water and sodium chloride solutions
15C to 30C
refractometer reading can be corrected for presence of high glucose and protein

87
Q

SG >1.035 measured by refractometer

A

= pt who receives radiocontrast media, dextran, mannitol
reagent test strip preffered!

88
Q

microscopic analysis required if these are pos

A

leukocyte
nitrite
blood
protein

89
Q

to standardize the microscopic examination of urine sediment, what must be maintained?

A

constant specimen, centrifugal force and sediment volume

90
Q

stain used for urien sediment

A

Sternheimer-Malbin
supravital stain; safranin O and crystal violet

91
Q

urinalysis procedure

A
  • ten fields at 10X for casts
  • ten fields at 40X for crystals, cells, microorganisms
92
Q

SG equation

A

density of urine/ density of equal vol of water

93
Q

isothenuria

A

1.010 SG

94
Q

hypothenuria

A

urine with SG <1.010; dilute urine

95
Q

hyperthenuria

A

urine with SG >1.010; concentrated urine

96
Q

polarizing light microscopy

A

used to detect birefringent urine elements such as uric acid and cholesterol
- refract light in two directions; 90 degrees from each other

97
Q

when are casts formed?

A

when uromodulin, a renal protein, congeals in distal tubules and collecting ducts during renal stasis

98
Q

where are narrow casts produced?

A

distal tubles

99
Q

broad casts

A

collecting ducts

100
Q

how do cells get incorporated into casts?

A

if cells are present in tubular lumen when the congealing of protein occurs

101
Q

clinical significance of hyaline casts

A

can be observed after exercise or stress
can be increased in pathological conditions

102
Q

clinical significance of granular casts

A

can be found in normal urine (exercise) and in urine from individuals with renal disease

103
Q

clinical significance of RBC cast

A

-bleeding in the nephron
- most commonly observed in glomerulonephritis and are associated w proteinuria

104
Q

WBC cast typically composed of

A

neuts; so may appear granular

105
Q

WBC cast significance

A
  • infection or inflammation in the nephron
  • commonly observed in pyelonephritis
  • also seen in acute interstitial nephritis and glomerular nephritis
106
Q

epithelial cell cast contains…

A

renal tubular cells

107
Q

epithelial cell cast significance

A

advanced renal tubular disease => stasis
- may be caused by heavy metals, drugs, viral infections, transplant rejection
- also seen in pyelonephritis w leukocyte cast

108
Q

casts that contain unstained, spherical, highly refractile fat droplets

A

fatty cast

109
Q

neutral fats and triglycerides can be stained with

A

Sudan III( orange)
Oil Red O

110
Q

fatty cast should be accompanied by

A

proteinuria and oval fat bodies, free fat droplets

111
Q

cholesterol can demonstrate as …

A

Maltese cross under polarizing light

112
Q

fatty cast most commonly associated with …

A

nephrotic syndrome and may be observed in toxic tubular necrosis, DM, crush injuries

113
Q

waxy casts (3)

A
  • more refractile than hyaline
  • may have broken ends
  • colourless or maybe a uniform purple
114
Q

clinical significance of waxy casts

A

found in extreme urine stasis; chronic renal failure

115
Q

T or F. Morphlogy of erythrocytes varies with urine specific gravity

A

T!

116
Q

hypersthenuria = red cells appear

A

crenated

117
Q

hyposthenuria = red cells appear

A

large and empty

118
Q

staining of erythrocytes varies on urine pH

A

neutral = pink purple
acidic = pink/unstained
alkaline - purple

119
Q

macroscopic hematuria

A
  • clinical significance of RBCs in urine
  • > 100 cells/HPF
  • advanced glomerular isease
  • truama and coag disorders
120
Q

microscopic hematuria

A
  • clinical significance of RBCs in urine
  • early glomerular disease
  • malignancy
  • renal clculi
121
Q

the predom type of leukocyte in urine

A

neutrophil

122
Q

in __________, neuts may swell and appear as a glitter cells

A

hyposthenuria

123
Q

neutrophil lysis is increased in …

A

alkaline urine and hyposthenuria

124
Q

when are eosinophils seen in urine

A
  • drug-induced interstitial nephritis
  • can be differentiated using a Hansel stain
125
Q

lymphocytes in urine

A

increased numbers in renal transplant rejection

126
Q

these are REPORTED, and cells enumerated as part of WBC count

A

WBC Clumps

127
Q

clinical significance of squamous epi cell

A

NOT significant
cells originate in female genitalia and urethra and lower urethra of men

128
Q

these cells are smaller than squamous cells and have various shapes

A

transitional epi cells
- spherical, polyhedral, caudate
- cytoplasm light purple
- well-defined CENTRAL nuclei

129
Q

clinical significance of transitional epi cells

A
  • renal calyx
  • bladder
  • ureters
  • catheterization
130
Q

renal tubular epi cells

A
  • not very common
  • smaller than squamous cells and have various shapes
  • columnar w coarse granules; oval, and cuboidal
  • eccentric nuclei that stain blue-purple
131
Q

clinical significance of renal tubular epis

A
  • originate from PCT and DCT and CDs of nephron
  • presence = tubular damage
132
Q

renal tubular epi cells that have absorbed lipids

A

oval fat bodies

133
Q

oval fat bodies confirmed with

A

polarizing microscopy
Sudan III or oil red O
cholesterol = maltese cross under polarized light

134
Q

clinical significance of oval fat bodies

A

lipiduria is associated with nephrotic syndrome and severe tbular necrosis and DM and trauma to long bones

oval fat bodies, free fat droplets, and fatty casts usually seen together
- proteins also pos on dipstick

MLSCI 262 (21 decks)

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