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MLSCI 263 > LAB - Urinalysis Module > Flashcards

LAB - Urinalysis Module Flashcards

1
Q

urine sample types

A
  • random
  • first morning
  • 24 hour
  • midstream
  • catheterized
  • suprapubic
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2
Q

when should urine specimens be processed?

A

within 2 hours of collection

- if not possible = store at 2 -8 C; protected from light

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3
Q

first-morning urine

A
  • most concentrated
  • ideal specimen for routine screening
  • purpose: routine, pregnancy, orthostatic protein
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4
Q

24 hr/timed specimen

A
  • some solutes measured in urine exhibit diurnal variation
  • carefully timing these collections allows for accurate quantitative measurement of changes
  • purpose = quantitative tests
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5
Q

catheterized urine sample

A
  • tube passed through urethra and into the bladder to collect
  • this urine is sterile
  • purpose = bacterial cultures
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6
Q

midstream clean catch

A
  • the genital area is cleaned before patient voids a small amount of urine to the toilet; then into container
  • reduces sample contamination with epithelial cells and skin flora
  • purpose = routine, bacterial cultures
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7
Q

suprapubic urine specimen

A
  • needle inserted through abdomen into bladder to collect urine
  • sterile
  • purpose = bacterial culture, cytology
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8
Q

overview of urinalysis

A

physical
chemical
microscopic

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9
Q

physical examination of urine

A
  • color
  • clarity
  • odor
  • specific gravity
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10
Q

chemical examination of urine

A
  • leukocyte esterase
  • nitrites
  • urobilinogen
  • protein
  • pH
  • blood
  • ketones
  • bilirubin
  • glucose
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11
Q

microscopic examination of urine

A

to evaluate microscopic elements present in urine sediment under specific circumstances

  • casts
  • cells
  • crystals
  • microorganisms
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12
Q

urine colour can be affected by:

A
  • concentration (hydration)
  • excreted metabolites
  • medications
  • chemicals
  • cellular content
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13
Q

when is urine amber in colour?

A
  • bilirubin (pathological)

- dehydration (non-path)

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14
Q

when is urine pink/red?

A
  • RBCs (cloudy), hemoglobin (clear), myoglobin, porphyrins (pathological)
  • beets, methyldopa (non-pathological)
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15
Q

when is urine orange?

A
  • bilirubin (pathological)

- carrots, riboflavin, rhubarb (non-path)

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16
Q

when is urine brown/black?

A
  • bilirubin, melanin, methemoglobin (path)

- iron compounds, levodopa, quinine (non-path)

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17
Q

when is urine red/brown?

A

porphobilin

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18
Q

when is urine blue/green?

A
  • biliverdin, Pseudomonas (pathological)

- methylene blue (non-path)

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19
Q

cloudiness of urine can be caused by

A

precipitating amorphous substances

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20
Q

gradine urine clarity

A
  • look from top and side of sample

- ensure it is adequately mixed before examination

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21
Q

dipstick urinalysis

A
  • routine
  • uses reagent strips
  • strips composed of absorbent chemical pads attached to plastic strip
  • colorimetric or enzymatic rxn occurs when pad comes into contact with urine
  • after specific time = colour compared to a chart
    = semiquantitative measure
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22
Q

a positive ___ ____, ____, _____ or _____ dipstick requires microscopic analysis

A
  • leukocyte esterase
  • nitrite
  • protein
  • blood
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23
Q

dipstick urinalysis - nitrite

A
  • screening for UTIs (bacteriuria)
  • cystitis, pyelonephritis
  • Enterobacteriaceae produce reductase, reducing nitrate to nitrite
  • Greiss reaction
    > any shade of pink is pos
    > bacteria must have sufficient contact tie with nitrate to produce nitrite (4 hrs)
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24
Q

Greiss reaction

A
  • nitrite urinalysis (dipstick)
  • acidic pH, nitrate reacts w aromatic amine to form a diazonium salt
  • salt reacts with tetrahydro benzoquinoline to produce pink azo dye
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25
Q

false positives in nitrite test for dipstick

A
  • improper storage
    > leading to bacterial growth
  • pigmented urine and colour markers
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26
Q

false negatives for nitrite disptick urinalysis

A
  • gram pos bacteria or yeast causing infection
  • low contact time
  • high ascorbic acid
  • high specific gravity
  • no nitrate in diet
  • reduction of nitrite to nitrogen in high bacterial cocntn
  • antibiotics
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27
Q

urobilinogen dipstick urinalysis

A
  • small amount is normally found in urine
  • degradation product of bilirubin
  • increased in liver disease and hemolytic disorders
  • Ehlrich reaction
  • negative, 0.2, or 1
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28
Q

Ehlrich reaction

A

urobilinogen reacts with p-dimethylaminobenzaldehyde at an acidic pH
- produces a range of pink-red colours

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29
Q

urobilinogen dipstick urinalysis false positive

A
  • Ehrlich-reactive compounds
    > Porphobilinogen
    > some drugs
  • pigmented urine and colour maskers
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30
Q

urobilinogen dipstick urinalysis false negative

A
  • improper storage
    > exposure
    > storage at room temperature
  • acidic urine
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31
Q

leukocyte esterase dipstick urinalysis

A
  • leukocytes are not normally found in urine
  • increased urinary leukocytes are found in UTIs and inflammation
  • detects esterases found in granulocytes
  • leukocyte esterases hydrolyze an acid ester on the dipstick pad to produce an aromatic compound and an acid
  • aromatic compound reacts with diazonium salt to produce an azo dye
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32
Q

false positives for leukocyte esterase dipstick

A
  • strong oxidizing agents

- color markers (nitrofurantoin)

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33
Q

false negatives for dipstick urinalysis leukocyte esterase

A
  • protein >5 g/L
  • glucose >30 g/L
  • ascorbic acid
  • oxalic acid
  • high specific gravity
  • antibiotics (gentamicin, cephalexin, cephalothin, tetracycline)
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34
Q

protein dipstick urinalysis

A
  • persistent proteinuria is associated with glomerular or tubular damage
  • test strips primarily detect albumin
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35
Q

protein error of indicators (protein dipstick)

A

> indicators release protons when proteins are present
proteins accept protons from the indicator
at a buffered constant pH 3.0, indicator is yellow
as protein conctn increases, colour changes from yellow to green and blue
semiquantitative results

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36
Q

false positive for protein urine dipstick

A
  • highly buffered alkaline urine
  • prolonged contact of pad with urine (washes buffer off)
  • high specific gravity
  • pigmented urine
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37
Q

false negative for protein urine dipstick

A

non-albumin proteins

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38
Q

dipstick urinalysis = pH

A
  • used to detect acid-base disorders
  • under normal kidney function
    > acidic pH = respiratory or metabolic acidosis
    > alkaline pH = respiratory or metabolic alkalosis
  • double indicator system
    > methyl red (colour change from pH 4 to 6; red to yellow)
    > bromothymol blue (colour change at pH 6 to 9; yellow to blue)
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39
Q

false increase for pH dipstick

A
  • improper storage
    > urine turns alkaline on standing
    > pH > 8.5 is not physiologically possible
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40
Q

false decrease for pH dipstick

A
  • run-over from adjacent protein pad buffer
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41
Q

blood dipstick urinalysis

A
  • hematuria (renal calculi, glomerulonephritis, pyelonephritis, trauma)
  • hemoglobinuria (transfusion rxns, hemolytic anemia, severe burns, infections)
  • myoglobinuria (rhabdomyolysis, trauma/crush syndromes, drug abuse, toxic to renal tubules)
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42
Q

blood dipstick reaction

A
  • peroxidase-like activity of hemoglobin catalyzes a rxn between peroxide from Hb or myoglobin and a chromogen
  • produces an oxidized blue-green chromogen
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43
Q

false positive for blood dipstick

A
  • menstrual contamination
  • strong oxidizing agents
  • bacterial peroxidase
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44
Q

false negative for blood dipstick

A
  • high SG crenates red cells
  • high nitrite concentrations
  • improper mixing = red cells settle at bottom
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45
Q

SG for dipstick urinalysis

A
  • density of a solution when compared to an equal volume of distilled water (SG 1.000) at same temp
  • urine has dissolved solutes, SG measures the density of dissolved solutes
    > isosthenuric = 1.010
    > hyposthenuric = <1.010
    > hypersthenuric = >1.010
  • monitors hydration and dehydration
  • measures the kidney’s ability to concentrate urine
  • decreased in diabetes insipidus
46
Q

reaction of SG dipstick

A
  • reagent strip contains a polyelectrolyte in alkaline medium and pH indicator
  • polyelectrolyte releases protons to be released in proportion to amount of ions in urine
  • higher the urine conctn, the greater the amount of protons released and the lower the pH
  • indicator measures pH change from blue to green to yellow
47
Q

false positive and negative of SG dipstick

A

FP
- high protein (anions)

FN
- urine pH >6.5; added 0.005 to SG readings to correct

48
Q

ketones dipstick urinalysis

A
  • intermediate products of liver fat metabolism
  • along with acetone, acetoacetic acid (detected by test pad), B-hydroxybutyrate
  • monitoring type I diabetes mellitus
    > ketonuria indicates insulin deficiency
  • starvation, strenuous exercise, vomiting
  • inherited metabolic disorders
  • malabsorption/pancreatic disorders
49
Q

reaction for ketones dipstick

A
  • acetoacetic acid in alkaline conditions reacts with sodium nitroprusside
  • produces purple colour
50
Q

false pos for ketones dipstick

A
  • highly pigmented urine and colour maskers
  • large amounts of levodopa
  • medication with sulfhydryl groups (MESNA, captopril)
51
Q

false neg for ketones dipstick

A
  • improper storage
    > bacterial breakdown of acetoacetic acid
    > volatilization of acetone
52
Q

bilirubin dipstick analysis

A
  • conjugated bilirubin is early indicator of liver disease
    > hepatitis, cirrhosis, other liver disorders
  • biliary obstruction
    > gallstones, tumors
  • diazo reaction
53
Q

Diazo rxn

A

bilirubin dipstick

  • bilirubin reacts w diazonium salt in acid medium
  • produces a pink to violet azo dye
54
Q

false pos in bilirubin dipstick

A
  • pigmented urine and colour maskers

- medication

55
Q

false neg in bilirubin dipstick

A
  • improper storage
    > exposure to light
  • high ascorbic acid
  • high nitrite
56
Q

glucose dipstick urinalysis

A
  • detection and monitoring of DM
  • not normally in urine
  • glucose appears in urine when levels exceed renal threshold
    > DM, advanced renal disease, pancreatitis, pregnancy, hyperthyroidism
  • glucose oxidase rxn
57
Q

glucose oxidase rxn

A
  • glucose dipstick
  • double sequential enzyme rxn
    > glucose oxidase catalyzes the oxidation of glucose into gluconic acid and peroxide
    > peroxidase catalyzes the rxn between the peroxide and a chromogen
58
Q

false pos in glucose dipstick

A
  • contamination with oxidizing agents or detergents
59
Q

false neg for glucose dipstick

A
  • high ascorbic acid
  • high ketones
  • high SG and low temps decrease senstivity
  • improper storage = bacterial glycolysis
60
Q

supravital stain used for urine microscopy

A

Sternheimer-Malbin
> crystal violet and safranin
> staining the sediment facilitates the ID and differentiation o cells, crystals, casts, and other microscopic elements by increasing their contrast

61
Q

what are casts?

A
  • made up of uromodulin (Tamm-Horsfall protein) matrix
  • formed in lumens of distal and convoluted tubules
  • under normal conditions, uromodulin is excreted by renal tubules at a constant rate
62
Q

factors affecting cast formation

A
  • renal stasis
  • increase acidity
  • presence of abnormal ionic or protein constituents
63
Q

characteristic of casts

A

parallel sides and rounded ends

64
Q

broad vs narrow casts

A
  • broad casts can be formed in collecting ducts

- narrow casts = ascending loop of Henle or distal convoluted tubule

65
Q

hyaline cast

A
  • colourless with visible protein gel matrix
  • varied morphology
  • increase visualization w phase contrast microscopy
  • NOT clinically significant
  • non-pathological (exercise, stress, dehydration, heat exposure)
  • pathological (acute glomerulonephritis, pyelonephritis, chronic renal disease congestive heart failure with other cast types)
  • correlating dipstick = + protein
66
Q

hyaline casts sources of error

A

mucus, fibers, hair

67
Q

granular casts

A
  • can have fine or coarse granules in protein matrix
68
Q

clinical significance of granular casts

A
  • can originate from lysozymes of renal epithelial cells; disintegration of cellular casts, filtered protein aggregates
  • nonpathological = increased in strenuous exercise
  • pathological = increased in glomerulonephritis, pyelonephritis, renal disease
69
Q

correlating urinalysis of granular casts

A
  • dipstick = + protein

- other microscopy = RBCs, WBCs, cellular casts

70
Q

RBC casts

A
  • orange-red cells fill a protein matrix
  • purplish if stained
  • indicates bleeding in nephron and glomerular damage
  • associated with glomerulonephritis and proteinuria
71
Q

RBC casts correlating urinalysis

A
    • protein or dipstick as well as + blood

- RBCs (other microscopy)

72
Q

WBC casts

A
  • neutrophils packed in a protein matrix
  • may appear granular, have multi-lobed nuclei visible
    0 infection or inflammation in nephron
  • present in pyelonephritis (upper UTI)
  • also present in acute interstitial nephritis and glomerulonephritis
73
Q

correlating dipstick for WBC cast

A
    • protein
    • leukocyte esterase
  • WBCs (other microscopy)
73
Q

correlating dipstick for WBC cast

A
    • protein
    • leukocyte esterase
  • WBCs (other microscopy)
74
Q

epithelial cell casts

A
  • renal tubule epithelial cells
  • indicates advanced renal tubular destruction resulting in urine stasis
  • heavy metal, chemical, drug toxicology
  • viral infections
  • transplant rejection
  • also seen in pyelonephritis w WBC casts
75
Q

correlating dipstick and other microscopy for epithelial cell casts

A
    • protein

- other microscopy = renal tubule epithelial cells

76
Q

fatty casts

A
  • seen with oval fat bodies and fat droplets
  • highly refractile
  • fat droplets and oval fat bodies attached to cast matrix
  • can visualize with Sudan III or Oil Red O stains
  • cholesterol ‘Maltese cross’
77
Q

clinical significance of fatty casts

A
  • disorders causing lipiduria
  • most commonly seen in nephrotic syndrome
  • also seen in toxic tubular necrosis, DM, crush injuries
78
Q

fatty casts correlating urinalysis

A
    • dipstick protein

- renal tubule epithelial cells

79
Q

waxy casts

A
  • brittle and refractile
  • appear fragmented and have jagged ends
  • side notches
  • indicates extreme urine stasis and chronic renal failure
  • seen with other cast types
    • protein dipstick
  • cellular and granular casts, WBCs, and RBCs
  • sources of error = fibers, fecal material
80
Q

erythrocytes in urine

A
  • appear crenated in concentrated urine
  • appear as ghost cells in dilute urine
  • associated w glomerular membrane damage or vascular injury in genitourinary tract
  • macroscopic hematuria
    > cloudy red-brown urine
    > over 100 cells/hpf
    > advanced glomerular damage
  • microscopic hematuria
    > early glomerular disorders; malignancy; renal calculi
81
Q

correlating urinalysis for erythrocytes in urine

A
    • blood for dipstick

- colour

82
Q

sources of error for erythrocytes in urine

A
  • yeast
  • oil droplets
  • air bubbles
83
Q

leukocytes

A
  • predominantly neutrophils
    > larger than RBCs, contain granules, and are multilobed
  • hypotonic urine = swell and appear as glitter cells
  • alkaline urine = lyse and lose nuclear detail
84
Q

clinical significance of leukocytes in urine

A
  • Pyuria = increased WBCs in infection or inflammation of the genitourinary system
    > pyelonephritis, cystitis, prostatis, urethritis
  • glomerulonephritis, lupus erythematosus, interstitial nephritis, tumors
  • eosinophils = drug-induced interstitial nephritis
  • small amount in UTIs and renal transplant rejection
  • stained with Hansel stain
85
Q

correlating urinalysis for leukocytes in urine

A
    • leukocyte esterase
    • nitrite
  • SG
  • pH
86
Q

sources of error for leukocytes

A

renal tubule epithelial cells

87
Q

squamous epithelial cells

A
  • abundant, irregular cytoplasm
  • prominent nucleus
  • not clinically significant
  • from the linings of the vagina and female urethra
  • may be increase in contaminated midstream clean catch collections
  • correlating urinalysis = clarity
88
Q

transitional epithelial cells

A
  • smaller than squamous
  • spherical, polyhedral, or caudate
  • centrally located nucleus
  • from renal pelvis, calyces, ureters, bladder, or upper male urethra
  • increased after catheterization
  • correlating urinalysis = clarity
89
Q

sources of error for transitional epithelial cells

A

renal tubular cells = look similar to spherical transitional epithelial cells

90
Q

renal tubular epithelial cells

A
  • smaller than squamous epi cells
  • coarse granular cytoplasm
    > columnar or convoluted
    > eccentric round nucleus
  • can originate from proximal convoluted tubule, distal or collecting duct
  • presence = tubular necrosis
    • leukocyte esterase and nitrite
91
Q

oval fat bodies

A
  • highly refractile RTE cells
  • seen with free-floating fat droplets
  • confirm by staining with Sudan III or Oil Red O under polarized light
    > stain for presence of triglyceride and neutral fats
    > cholesterol has a Maltese cross
  • RTE cells that have absorbed lipids
  • nephrotic syndrome
  • severe tubular necrosis, DM, bone trauma
92
Q

urine crystals

A
  • formed by precipitation of urine solutes
    > inorganic salts, organic compounds, and medications
  • affected by: temp, concentration, pH, urine flow
  • identification is based on pH and microscopic appearance
  • classified as normal or abnormal
93
Q

uric acid crystals

A
  • normal acidic urine crystals
  • colourless to yellow-brown
  • various shapes; six-sided
  • highly birefringent
  • increased in gout
94
Q

amorphous urates

A
  • normal
  • yellow-brown; appear pink macroscopically
  • amorphous granules = may clump
  • birefringent
95
Q

acid urates

A
  • rare

- larger granules with spicules

96
Q

sodium urates

A
  • rare

- needle shaped

97
Q

calcium oxalate

A
  • normal acidic/ neutral urine crystals
  • can also be present in neutral and alkaline urine (rare)
  • colorless
  • various shapes = octahedral dihydrate (most common), dumbbell-shaped or oval monohydrate
    > increased in ethylene glycol poisoning
  • birefringent
98
Q

cystine crystals

A
  • abnormal acidic urine crystals; rare
  • colourless
  • hexagonal plates (thick/thin)
  • birefringent (thick)
  • cystinuria = found in inherited metabolic disorders that prevent reabsorption of cystine
99
Q

cholesterol in urine

A
  • abnormal acidic urine crystals; rare
  • coloirless
  • rectangular plate and notched corners
  • birefringent
  • associated with lipiduria (nephrotic syndrome)
  • seen with fatty casts and oval fat bodies
100
Q

bilirubin

A
  • abnormal acidic urine crystals; rare
  • yellow/brown in colour
  • clumped needles or granules
  • liver disease
  • seen with a positive bilirubin test strip
101
Q

tyrosine

A
  • abnormal acidic/neutral urine crystals (rare)
  • colourless to yellow
  • needles that form clumps or rosettes
  • liver disease or inherited metabolic disorder
  • seen with leucine crystals and a positive bilirubin dipstick result
102
Q

bacteria in urine

A
  • spheres or rods
  • not normally in urine
  • accompanied by WBCs in urinary tract infections
  • may multiple due to improper storage at room temp
    • nitrite and alkaline pH and + leukocyte esterase
  • sources of error = amorphous phosphates
103
Q

yeast

A
  • refractile
  • may contain buds
  • may contain branched forms in severe infections
  • seen n diabetic, immunocompromised patients with vaginal moniliasis
  • accompanied by WBCs
  • glucose and + leukocyte esterase
104
Q

trichomonas vaginalis

A
  • motile pear-shaped
  • flagellated
  • sexually transmitted parasite
    • leukocyte esterase
105
Q

spermatozoa

A
  • tapered oval head with long thin tails
  • found in both male and female specimens
  • reporting in under-aged females may have legal implications
106
Q

mucus in urine

A
  • thread-like structures
  • low refractive index
  • may clump
  • composed of uromodulin
  • commonly seen in female specimens
107
Q

leucine in urine

A
  • abnormal acidic/neutral urine crystals
  • rare
  • yellow/brown
  • spheres with concentric circles and radial striations
  • associated with liver disease or inherited metabolic disorder
  • seen w tyrosine crystals and a positive bilirubin dipstick result
108
Q

rules for manual urinalysis count

A
  • 10 fields at 10X for casts

- 10 fields at 40X for cells, crystals, and microorganisms

109
Q

renal stasis

A

where slow urine flow leads to buildup of debris (stone) or potentiates infection

MLSCI 263 (31 decks)

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