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AUBF > Chemical Examination > Flashcards

Chemical Examination Flashcards

1
Q

Reagent strips enable rapid screening of urine specimens for:

A

✓pH
✓Protein
✓Glucose
✓Ketones
✓Blood
✓Bilisrubin
✓Urobilinogen
✓Nitrite
✓Leukocyte esterase

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2
Q

Routinely used for chemical analysis of urine.

A

Reagent strips

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3
Q

Four commonly used brands of commercial reagent strips are:

A

✓Multistix (Siemens Healthcare Diagnostics Inc., Deerfield, IL)
✓Chemstrips (Roche Diagnostics, Indianapolis, IN)
✓vChemStrips (Iris Urinalysis-Beckman Coulter Inc., Brea, CA)
✓Aution Sticks (Arkray Inc., Kyoto, Japan) 3

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4
Q

commercial _____ or _____ consists of reagent impregnated test pads that are fixed to an inert plastic strip

A

reagent strip or dipstick

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5
Q

Reducing agents such as _____ have the potential to adversely affect several reagent strip test results

A

Ascorbic acid

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6
Q

reporting of reagent strips:
The ____ and the ____are exceptions; these results are estimated in their respective units.

A

specific gravity, the pH

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7
Q

REAGENT STRIP
Results are reported (depending on the test):

A

✓In concentration (milligrams per deciliter)
✓As small, moderate, or large
✓Using the plus system (1+, 2+, 3+, 4+)
✓As positive, negative, or normal

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8
Q

Reagent strips have significantly:

A
  1. Reduced the time required for testing
  2. Reduced costs (e.g., reagents, personnel)
  3. Enhanced test sensitivity and specificity
  4. Decreased the amount of urine required for testing
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9
Q

To ensure the integrity of reagent strips, their ____ is essential, and the manufacturer’s directions must be followed.

A

proper storage

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10
Q

REAGENT STRIPS Care and Storage
❑All reagent strips must be protected from ____, ____, ____, and ____.
❑Any strips showing evidence of deterioration,
contamination, or improper storage should be ______.
❑Tight-fitting lids, along with desiccants or drying agents within the product container, help eliminate test pad _____ due to _____.

A
  • moisture, chemicals, heat, and light
  • discarded
  • deterioration, moisture
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11
Q

REAGENT STRIPS Care and Storage
❑Fumes from volatile chemicals, acids, and bases can adversely affect the test pads and should be avoided.
❑All reagent strip containers protect the reagent strips from____ and ____; however, the containers themselves must be protected to prevent fading of the color chart located on the label of the container.
❑Reagent strips should be stored in their original containers at temperatures below ____; they are stable until the expiration date indicated on the label.

A
  • ultraviolet rays, sunlight
  • 30°C (86°F)
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12
Q

✓Ensures that the reagent strips are functioning properly.
✓Confirms the acceptable performance and technique of the laboratorian using them.

A

Quality Control Testing

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13
Q

Quality Control Testing:
____ and ____ control levels must be used to check the
reactivity of reagent strips.

A

negative and positive control

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14
Q

Quality Control Testing:
____ or ____ can serve as acceptable negative/positive controls.

A

Commercial or laboratory-prepared materials

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15
Q

aliquoting a well-mixed urine specimen from the daily workload and having a different laboratory analyze the specimen.

A

Interlaboratory

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16
Q

aliquoting a well-mixed urine specimen from the daily workload and having a technologist on each shift analyze the specimen.

A

Intralaboratory

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17
Q

_____ duplicate testing can also be used to evaluate the technical competency of
laboratorians.

A

Intralaboratory

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18
Q

____ duplicate testing checks the entire urinalysis procedure and detects innocuous changes when manual urinalyses are performed, such as variations in the speed of centrifugation and in centrifuge brake usage.

A

Interlaboratory

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19
Q

TABLET AND CHEMICAL TESTS
Care and Storage:
➢Susceptible to deterioration from
exposure to ____, ____, and ____.

A

light, heat, and moisture.

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20
Q

CHEMICAL TESTS
✓ ____ – detect protein
✓ ____ – detect porphobilinogen (PBG)
✓ ____ – detect porphyria
✓ ____ – detect glucose

A

✓Sulfosalicylic acid (SSA) precipitation test
✓Hoesch test
✓Watson-Schwartz test
✓Benedict’s test

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21
Q

When new reagents are prepared, they should be tested in _____ to ensure equivalent performance.

A

parallel with current “in-use” reagents

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22
Q

Urine specimen (room temperature) – it must be tested within ____ after collection to avoid erroneous results caused by changes that can occur in unpreserved urine

A

2 hours

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23
Q

Urine specimen (Refrigerated) – it should be allowed to ____ before testing with reagent strips to avoid erroneous results

A

warm up to room temperature

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24
Q

Urines that are highly pigmented due to medications can lead to_____ reagent strip test results because the true color reaction is masked by the pigment present.

A

false-positive

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25
Q

Cite the 10 CHEMICAL TEST

A

✓Specific Gravity
✓pH
✓Protein
✓Blood
✓Leukocyte Esterase
✓Nitrite
✓Glucose
✓Ketones
✓Bilirubin and Urobilinogen
✓Ascorbic Acid

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26
Q

*Specific Gravity Clinical Significance
___ same as pure water; suspect
adulteration of urine specimen

A

1.000

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27
Q

*Specific Gravity Clinical Significance
___ indicates presence of iatrogenic
substance (e.g., radiographic contrast media,
mannitol)

(physiologically impossible)

A

> 1.040

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28
Q

*Specific Gravity Clinical Significance
___ Indicates average solute and water intake and excretion

A

1.010–1.025

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29
Q

Specific Gravity Clinical Significance
___ Dilute urine; associated with
increased water intake or water diuresis (e.g.,
diuretics, inadequate secretion/action of
ADH)

A

1.001–1.009

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30
Q

*Specific Gravity Clinical Significance
___ Concentrate urine; associated with dehydration, fluid restriction, profuse sweating, osmotic diuresis

A

1.025–1.035 (1.040 maximum)

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31
Q

*Specific Gravity Principle
Ionic solutes present in the urine cause protons to be released from a polyelectrolyte. As protons are released, the pH decreases and produces a color change of the ____ indicator from ____ to ____

A
  • bromthymol blue
  • blue-green to yellow-green
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32
Q

*Specific Gravity Principle
❑Specificity
* Detects only ____; provides “estimate” in 0.005 increments

A
  • ionic solutes
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33
Q

*pH Clinical Significance
❑Urine pH varies from ____
❑Average individual excretes slightly acidic urine of pH ____

A
  • 4.5 to 8.0
  • 5.0 to 6.0
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34
Q

*pH Clinical Significance
___ suspect adulteration of urine
specimen.

A

<4.5

35
Q

*pH Clinical Significance
___ indicates:
* Presence of an iatrogenic alkaline
substance (intravenous medication or
agent)
* Improperly stored urine specimen
* Contamination with an alkaline chemical
(preservative)

A

> 8.0

36
Q

*pH Clinical Significance
___ associated with:
* Diet (high protein and cranberry ingestion) , sleep, metabolic acidosis (e.g., ketoacidosis, starvation, severe diarrhea, uremia, poisons—ethylene glycol, methanol), respiratory acidosis (e.g., emphysema, chronic lung disease), urinary system disorders: UTI with acid-producing bacteria (Escherichia coli),
chronic renal failure, uremia, medications used to induce: ammonium chloride, ascorbic acid,
methionine, mandelic acid

A

4.5 - 6.9 (Acid urine)

37
Q

*pH Clinical Significance
associated with:
* Diet(vegetarian, citrus fruits, low carbohydrate), metabolic alkalosis (e.g., vomiting, gastric lavage), respiratory alkalosis (e.g., hyperventilation), urinary system disorders: UTI with urease producing bacteria (Proteus sp., Pseudomonas sp.), renal tubular acidosis, medications used to induce: sodium bicarbonate, potassium citrate, acetazolamide

A

7.0 - 7.9 (Alkaline urine)

38
Q

pH Reagent Strip Method
❑Principle: _____
* Indicators: ____ and ____ are used to give
distinct color changes from ___ to ___ to ___ (pH 5.0–9.0).
❑Specificity: pH; _____
* No interferences known; unaffected by protein concentration

A
  • Double-indicator system
  • methyl red and bromthymol blue,
  • orange to green to blue
  • hydrogen ion concentration
39
Q

alternative method of pH test that consists of a silver–silver chloride indicator electrode

A

pH meter

40
Q

CHEMICAL TESTS
Protein Clinical Significance
➢Normal urine – ____ (1 to 14 mg/dL) of protein each day
* one-third albumin and two-thirds globulins

A

150 mg

41
Q

Proteins that originate from the urinary tract:

A
  • Uromodulin (also known as Tamm-Horsfall protein)
  • Urokinase (enzyme)
  • Secretory immunoglobulin A
42
Q

first indicator of renal disease (albumin).

A

Proteinuria

43
Q

most common type of proteinuria
encountered and is the most serious

A

Glomerular proteinuria

44
Q

Proteinuria can be classified into four categories:

A

✓Prerenal or overflow proteinuria
✓Glomerular proteinuria
✓Tubular proteinuria
✓Postrenal proteinuria

45
Q

an increase in plasma low MW proteins leads to increased excretion in urine.

A

Prerenal or overflow proteinuria

46
Q

➢Normal proteins present in Prerenal or overflow proteinuria: __ __ __
➢Abnormal proteins: __

A
  • Myoglobin, Hemoglobin, Acute phase reactants
  • Ig light chains (Bence Jones protein – Multiple Myeloma)
47
Q

*Protein Methods
detects all proteins in urine—albumin and globulins.

A

Sulfosalicylic Acid Precipitation Test (SSA)

48
Q

Sulfosalicylic Acid Precipitation Test (SSA) is not frequently performed today because it is ___ and ____

A

nonspecific and time-consuming

49
Q

*PROTEIN Reagent Strip Tests Principle: ___
*Color change: ___
*Indicator used: ___
*Sensitivity: ___

A
  • Protein error of indicators
  • from yellow to blue-green
  • tetrabromophenolblue
  • More sensitive to albumin
50
Q

➢Monitoring of urine for low-level albumin.
➢Used for individuals with diabetes, hypertension, or peripheral vascular disease

A

Sensitive Albumin (Microalbumin) Tests

51
Q

Determination of an _____ reduces the numbers of false positive and false-negative test results.

A

A/C or protein-to-creatinine ratio

52
Q

*Blood Clinical Significance
❑ ____– abnormal quantity of red blood cells in
the urine (Cloudy or smoky urine).
❑ ____– indicates the urinary presence of hemoglobin (Clear urine).
❑ ____– indicates the urinary presence of
myoglobin.

A
  • Hematuria
  • Hemoglobinuria
  • Myoglobinuria
53
Q

*BLOOD Reagent Strip Tests Principle: ___
*Color change: ___
*Chromogen used: ___

A
  • Pseudoperoxidase activity
  • from Yellow to green
  • tetramethylbenzidine
54
Q

*Leukocyte Esterase Clinical Significance
❑Normal urine: ____
❑Pathologic urine: ____

A
  • 0 to 8 per hpf
  • 20 or more WBCs per microliter
55
Q

*Leukocyte Esterase Reagent Strip Test Principle: ___
*Color change: ___
*Specificity: ___

A
  • azo coupling reaction
  • from beige to violet
  • Detects only granulocytic leukocytes
56
Q

Routine screening for urine nitrite provides an important tool to identify urinary tract infection.

A

Nitrite

57
Q

___ are infecting the urinary tract and adequate bladder retention time is allowed, these bacteria convert dietary nitrate to nitrite

A

Nitrate-reducing bacteria

58
Q

*Nitrite Reagent Strip Principle: ___
*Color change: ___

A
  • Diazotization reaction followed by azo coupling reaction
  • from white to pink
59
Q

presence of glucose in urine

A

Glucosuria

60
Q

non-glucose sugars (e.g., fructose, sucrose,
lactose) or a combination of sugars are present in urine

A

Glycosuria

61
Q

is an inherited disorder characterized by an
inability to metabolize galactose to glucose

A

Galactosemia

62
Q

is the most common disease that causes
hyperglycemia and glucosuria

A

Diabetes mellitus

63
Q

*Glucose Reagent Strip Tests Principle: ___
*Specificity: ___

A
  • Double-sequential enzyme reaction
  • Specific for glucose
64
Q

method used for glucose

A

Copper Reduction Tests (Benedict’s test)

65
Q

A tablet version of Benedict’s test

A

Clinitest reagent tablet

65
Q

Reducing substances in urine that can cause positive copper reduction test:

A
  • Sugars (Glucose, Fructose, Galactose, Lactose, Maltose, except sucrose)
  • Ascorbic Acid
  • Cysteine
  • Homogentisic acid
66
Q

Ketone Formation
❑The terms ketones and ketone bodies identify three intermediate products of fatty acid metabolism:

A

✓Acetoacetate – 20%
✓β-hydroxybutyrate – 78%
✓Acetone – 2%

67
Q

ketones are excreted in the urine, 70 mg/dL (the renal threshold level)

A

Ketonuria

68
Q

Urine ketone excretion is about ____

A

20 mg/day

69
Q

*Ketone Reagent Strip Tests Principle: ___
*Color change: ___
*Chemstrip and vChem reagent strips include ____ in the reaction pad, which enables the detection of acetone
*Specificity: ____

A
  • Legal’s test—nitroprusside reaction
  • from beige to purple
  • glycine
  • Does not detect β-hydroxybutyrate
70
Q

Tablet test for the detection of ketones in urine is the ___

A

Nitroprusside Tablet Test (Acetest)

71
Q
  • orange-brown color of feces:
  • contribute to the color of urine
A
  • Urobilin and stercobilin
  • Urobilinogen
72
Q

abnormally increased amounts of bilirubin in urine.

A

Bilirubinuria

73
Q

abnormally increased amounts of bilirubin in the blood.

A

Hyperbilirubinemia

74
Q

the yellowish pigmentation of skin, sclera, tissues, and body fluids caused by bilirubin

A

Jaundice

75
Q

*Bilirubin Reagent Strip Test Principle: ____
*Color change: ____
*Physical Examination: ____

A
  • Azo coupling reaction
  • from light tan to beige or light pink
  • Foam test
76
Q
  • A tablet test for the detection of bilirubin in urine is the Ictotest method
  • Concentrations of bilirubin as low as ____ can be detected.
A
  • Diazo Tablet Test (Ictotest Method)
  • 0.05 to 0.1 mg/dL
77
Q

Specimen of choice for quantifying or monitoring of Urobilinogen

A

a 2-hour collection after the midday meal (i.e., 2 PM to 4 PM) “alkaline tide”

78
Q

Urobilinogen is ____ in acid urine and easily photo-oxidizes to ____

A
  • labile
  • urobilin
79
Q

Used to qualitatively screen for urobilinogen.

A

Classic Ehrlich’s Reaction

80
Q

*Urobilinogen Reagent Strip Tests Principle: ___
*Color change: ___
*Multistix strips: ___

A
  • azo coupling reaction
  • from light pink to dark pink
  • modified Ehrlich’s reaction
81
Q

is a strong reducing substance because of its ene-diol group.

A

Ascorbic acid

82
Q

Ascorbic acid color change on Reagent strip

A

from blue to orange

AUBF (4 decks)

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