MLSCI 263 > LAB - Urinalysis Module > Flashcards

LAB - Urinalysis Module Flashcards

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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
false positives in nitrite test for dipstick
- improper storage > leading to bacterial growth - pigmented urine and colour markers
26
false negatives for nitrite disptick urinalysis
- 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
27
urobilinogen dipstick urinalysis
- 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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Ehlrich reaction
urobilinogen reacts with p-dimethylaminobenzaldehyde at an acidic pH - produces a range of pink-red colours
29
urobilinogen dipstick urinalysis false positive
- Ehrlich-reactive compounds > Porphobilinogen > some drugs - pigmented urine and colour maskers
30
urobilinogen dipstick urinalysis false negative
- improper storage > exposure > storage at room temperature - acidic urine
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leukocyte esterase dipstick urinalysis
- 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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false positives for leukocyte esterase dipstick
- strong oxidizing agents | - color markers (nitrofurantoin)
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false negatives for dipstick urinalysis leukocyte esterase
- protein >5 g/L - glucose >30 g/L - ascorbic acid - oxalic acid - high specific gravity - antibiotics (gentamicin, cephalexin, cephalothin, tetracycline)
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protein dipstick urinalysis
- persistent proteinuria is associated with glomerular or tubular damage - test strips primarily detect albumin
35
protein error of indicators (protein dipstick)
> 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
36
false positive for protein urine dipstick
- highly buffered alkaline urine - prolonged contact of pad with urine (washes buffer off) - high specific gravity - pigmented urine
37
false negative for protein urine dipstick
non-albumin proteins
38
dipstick urinalysis = pH
- 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)
39
false increase for pH dipstick
- improper storage > urine turns alkaline on standing > pH > 8.5 is not physiologically possible
40
false decrease for pH dipstick
- run-over from adjacent protein pad buffer
41
blood dipstick urinalysis
- 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)
42
blood dipstick reaction
- peroxidase-like activity of hemoglobin catalyzes a rxn between peroxide from Hb or myoglobin and a chromogen - produces an oxidized blue-green chromogen
43
false positive for blood dipstick
- menstrual contamination - strong oxidizing agents - bacterial peroxidase
44
false negative for blood dipstick
- high SG crenates red cells - high nitrite concentrations - improper mixing = red cells settle at bottom
45
SG for dipstick urinalysis
- 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
reaction of SG dipstick
- 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
false positive and negative of SG dipstick
FP - high protein (anions) FN - urine pH >6.5; added 0.005 to SG readings to correct
48
ketones dipstick urinalysis
- 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
reaction for ketones dipstick
- acetoacetic acid in alkaline conditions reacts with sodium nitroprusside - produces purple colour
50
false pos for ketones dipstick
- highly pigmented urine and colour maskers - large amounts of levodopa - medication with sulfhydryl groups (MESNA, captopril)
51
false neg for ketones dipstick
- improper storage > bacterial breakdown of acetoacetic acid > volatilization of acetone
52
bilirubin dipstick analysis
- conjugated bilirubin is early indicator of liver disease > hepatitis, cirrhosis, other liver disorders - biliary obstruction > gallstones, tumors - diazo reaction
53
Diazo rxn
bilirubin dipstick - bilirubin reacts w diazonium salt in acid medium - produces a pink to violet azo dye
54
false pos in bilirubin dipstick
- pigmented urine and colour maskers | - medication
55
false neg in bilirubin dipstick
- improper storage > exposure to light - high ascorbic acid - high nitrite
56
glucose dipstick urinalysis
- 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
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glucose oxidase rxn
- 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
false pos in glucose dipstick
- contamination with oxidizing agents or detergents
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false neg for glucose dipstick
- high ascorbic acid - high ketones - high SG and low temps decrease senstivity - improper storage = bacterial glycolysis
60
supravital stain used for urine microscopy
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
what are casts?
- 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
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factors affecting cast formation
- renal stasis - increase acidity - presence of abnormal ionic or protein constituents
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characteristic of casts
parallel sides and rounded ends
64
broad vs narrow casts
- broad casts can be formed in collecting ducts | - narrow casts = ascending loop of Henle or distal convoluted tubule
65
hyaline cast
- 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
hyaline casts sources of error
mucus, fibers, hair
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granular casts
- can have fine or coarse granules in protein matrix
68
clinical significance of granular casts
- 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
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correlating urinalysis of granular casts
- dipstick = + protein | - other microscopy = RBCs, WBCs, cellular casts
70
RBC casts
- orange-red cells fill a protein matrix - purplish if stained - indicates bleeding in nephron and glomerular damage - associated with glomerulonephritis and proteinuria
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RBC casts correlating urinalysis
- + protein or dipstick as well as + blood | - RBCs (other microscopy)
72
WBC casts
- 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
correlating dipstick for WBC cast
- + protein - + leukocyte esterase - WBCs (other microscopy)
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correlating dipstick for WBC cast
- + protein - + leukocyte esterase - WBCs (other microscopy)
74
epithelial cell casts
- 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
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correlating dipstick and other microscopy for epithelial cell casts
- + protein | - other microscopy = renal tubule epithelial cells
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fatty casts
- 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'
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clinical significance of fatty casts
- disorders causing lipiduria - most commonly seen in nephrotic syndrome - also seen in toxic tubular necrosis, DM, crush injuries
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fatty casts correlating urinalysis
- + dipstick protein | - renal tubule epithelial cells
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waxy casts
- 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
erythrocytes in urine
- 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
correlating urinalysis for erythrocytes in urine
- + blood for dipstick | - colour
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sources of error for erythrocytes in urine
- yeast - oil droplets - air bubbles
83
leukocytes
- 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
clinical significance of leukocytes in urine
- 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
correlating urinalysis for leukocytes in urine
- + leukocyte esterase - + nitrite - SG - pH
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sources of error for leukocytes
renal tubule epithelial cells
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squamous epithelial cells
- 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
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transitional epithelial cells
- 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
sources of error for transitional epithelial cells
renal tubular cells = look similar to spherical transitional epithelial cells
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renal tubular epithelial cells
- 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
oval fat bodies
- 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
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urine crystals
- 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
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uric acid crystals
- normal acidic urine crystals - colourless to yellow-brown - various shapes; six-sided - highly birefringent - increased in gout
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amorphous urates
- normal - yellow-brown; appear pink macroscopically - amorphous granules = may clump - birefringent
95
acid urates
- rare | - larger granules with spicules
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sodium urates
- rare | - needle shaped
97
calcium oxalate
- 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
cystine crystals
- abnormal acidic urine crystals; rare - colourless - hexagonal plates (thick/thin) - birefringent (thick) - cystinuria = found in inherited metabolic disorders that prevent reabsorption of cystine
99
cholesterol in urine
- 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
bilirubin
- abnormal acidic urine crystals; rare - yellow/brown in colour - clumped needles or granules - liver disease - seen with a positive bilirubin test strip
101
tyrosine
- 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
bacteria in urine
- 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
yeast
- 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
trichomonas vaginalis
- motile pear-shaped - flagellated - sexually transmitted parasite - + leukocyte esterase
105
spermatozoa
- tapered oval head with long thin tails - found in both male and female specimens - reporting in under-aged females may have legal implications
106
mucus in urine
- thread-like structures - low refractive index - may clump - composed of uromodulin - commonly seen in female specimens
107
leucine in urine
- 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
rules for manual urinalysis count
- 10 fields at 10X for casts | - 10 fields at 40X for cells, crystals, and microorganisms
109
renal stasis
where slow urine flow leads to buildup of debris (stone) or potentiates infection
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