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[3Y1S] MT 6317 > U2.3 NPN : Urea [L] > Flashcards

U2.3 NPN : Urea [L] Flashcards

1
Q

Nitrogen-containing compounds measured after removal of proteins in specimen

A

Non-Protein Nitrogen

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2
Q

Non-Protein Nitrogen is measured by converting _____ to _______

A

converting nitrogen to ammonia

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3
Q

reagent used to convert nitrogen to ammonia

A

Nessler’s reagent

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4
Q

product measured spectrophotometrically (color)

A

yellow product

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5
Q

Measured by converting nitrogen to ammonia and subsequent reaction with Nessler’s reagent (K2[Hgl4]) to form a yellow product measured spectrophotometrically

A

Non-Protein Nitrogen

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6
Q

Select: Part of Non-Protein Nitrogen (NPN)

A. Urea
B. Creatinine
C. Glucose
D. Uric Acid

A

A B D

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7
Q

In urine, __________ contributes 4.5% of excreted nitrogen, while __________ contributes 1.7%.

A

Creatinine, Uric Acid

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8
Q

% of total Urea in Plasma

A

45-50

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9
Q

% of Urea in urine Concentration

A

86

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10
Q

Specimens used for Urea Determination

A

serum, urine & plasma

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11
Q

Also known as carbamide

A

Urea

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12
Q

Highest concentration in blood

A

Urea

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13
Q

Urea is produced in the _____ from amino groups (-NH2) and free ammonia

A

liver

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14
Q

Major excretory product of protein metabolism

A

Urea

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15
Q

Chemical formula of Urea

A

CO(NH2)2

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16
Q

T/F Clinical application of urea include evaluation of renal function

A

T

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17
Q

T/F Clinical application of urea includes assessing hydration status

A

T

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18
Q

T/F Clinical application of urea include determination of nitrogen balance

A

T

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19
Q

T/F Clinical application of urea include aid in the diagnosis of liver disease

A

F renal

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20
Q

T/F Clinical application of urea include verify adequacy of dialysis

A

T

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21
Q

Select: Clinical applications of Urea testing

A. Evaluation of renal function
B. Determination of blood glucose levels
C. Assessing hydration status
D. Verifying adequacy of dialysis

A

A C D

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22
Q

More appropriate term for quantification of urea

A

Blood Urea Nitrogen (BUN) Determination

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23
Q

BUN Determination

Conversion factor (mg/dL to mmol/L):

A

x 0.357

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24
Q

BUN Determination

BUN to Urea

A

Urea = BUN x 2.14

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25
Q

BUN Determination

Urea to BUN

A

BUN = Urea / 2.14

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26
Q

BUN Determination

Most frequently used method

A

ENZYMATIC METHOD

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27
Q

BUN Determination

Uses urease enzyme to catalyze hydrolysis of urea and the liberated ammonium ion (NH4+) is quantified.

A

ENZYMATIC METHOD

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28
Q

T/F the most frequently used method for BUN determination is the enzymatic method which uses the urease enzyme

A

t

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29
Q

BUN Determination

enzyme used to catalyze hydrolysis of urea and the liberated ammonium ion (NH4+) is quantified

A

urease

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30
Q

BUN Determination : Enzymatic Method

most common assay

A

Glutamate dehydrogenase (GLDH)-coupled enzymatic reaction

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31
Q

Select: Indicator Dye Method commonly used in the following systems

A. Automated Systems
B. Dry Reagent Strips
C. Spectrophotometers
D. Multilayer Film Reagents

A

A B D

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32
Q

BUN Determination : Enzymatic Method

best as a kinetic measurement

A

Glutamate dehydrogenase (GLDH)-coupled enzymatic reaction

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33
Q

T/F GLDH-coupled enzymatic reaction is best used for static measurements

A

F - best used as kinetic measurement

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34
Q

BUN Determination : Enzymatic Method

measures rate of disappearance of nicotinamide adenine dinucleotide (reduced NADH) at 340 nm

A

Glutamate dehydrogenase (GLDH)-coupled enzymatic reaction

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35
Q

GLDH coupled reaction for BUN determination measures the rate of disappearance of __________ at 340 nm.

A

NADH (reduced nicotinamide adenine dinucleotide)

36
Q

BUN Determination : Enzymatic Method

wavelength that measures rate of disappearance of nicotinamide adenine didnucleotide (reduced NADH)

A

340 nm

37
Q

T/F more ammonium ions result in a faster reduction of NADH to NAD+ in GLDH reaction

A

T

38
Q

BUN Determination : Enzymatic Method

used in automated systems, multilayer film reagents and dry reagent strips

A

Indicator dye

39
Q

BUN Determination : Enzymatic Method

measures color change due to change in pH

A

Indicator dye

40
Q

BUN Determination : Enzymatic Method

a specific and rapid test

A

Conductometric

41
Q

BUN Determination : Enzymatic Method

uses electrode to measure rate of increase in conductivity produced by ammonium ions

A

Conductometric

42
Q

BUN Determination

reference method

A

ISOTOPE DILUTION MASS SPECTROMETRY (IDMS)

43
Q

BUN Determination

uses isotopically-labeled compound for quantification

A

ISOTOPE DILUTION MASS SPECTROMETRY (IDMS)

44
Q

BUN Determination

detects characteristic fragments following ionization

A

ISOTOPE DILUTION MASS SPECTROMETRY (IDMS)

45
Q

Specimen considerations for Urea Determination

A

Sample: Serum, plasma or urine

46
Q

Odd One Out: Sample for BUN
A. Serum
B. Plasma
C. Urine
D. Saliva

A

D

*B - lithium heparinized plasma

47
Q

Select: Blood Urea Nitrogen (BUN) determination - Enzymatic method

A. Glutamate dehydrogenase (GLDH)-coupled enzymatic reaction
B. Colorimetric analysis
C. Conductometric
D. Isotope Dilution Mass Spectrometry (IDMS)

A

A C

48
Q

Tops that are not allowed for Urea Determination

A

Light Blue - sodium citrate
Grey - sodium fluoride

49
Q

Select All That Apply: Avoided or considered for urea determination,,

A. Using citrate as an anticoagulant
B. Using fluoride as an anticoagulant
C. Using hemolyzed samples
D. Processing the sample immediately or refrigerating it

A

A B C

50
Q

if urine samples are not processed within a few hours, they should be __________ to prevent bacterial consumption of urea

A

refrigerated

51
Q

dilution factor commonly used when diluting urine samples with normal saline for urea concentration analysis

A

1:20

51
Q

Select: Materials for urea determination
A. Serological pipet
B. Rubber aspirators
C. Ellitrol I (Normal Control)
D. Centrifuge
E. Spectrophotometer

A

A, B, C, D, E

52
Q

Urea Reagent Kit; Reagent 1

A

R1 Tris buffer (pH 7.6), ADP, α-ketoglutarate, urease, glutamate dehydrogenase, sodium azide

53
Q

Urea Reagent Kit; Reagent 2

A

NADH, sodium azide (irritates eyes and skin)

54
Q

T/F Sodium azide, present in both reagents, is safe and does not irritate the eyes or skin

A

F - sod azide irritates eyes and skin

55
Q

standard urea concentration is __________ mg/dL or _____ mmol/L, though this may vary depending on the manufacturer

A

50; 8.33

56
Q

Select: Materials for BUN Enzymatic Reaction
A. Serologic pipet
B. Hemocytometer
C. Spectrophotometer
D. Centrifuge

A

A C D

57
Q

in the BUN determination procedure, the sample volume is delivered by touching the tip of the pipet to the __________ of the tube

A

bottom

58
Q

T/F the working reagent is prepared by mixing 1 volume of reagent 1 with 2 volumes of reagent 2

A

F - 1 volume of Reagent 2

59
Q

T/F working reagent for urea determination should be prepared ahead of time before starting the analysis

A

F - only when starting analysis

60
Q

BUN Determination Procedure

Feed the solution in the machine at __ seconds for A1

A

27 seconds

61
Q

BUN Determination Procedure

Feed the solution in the machine at __ seconds for A2

A

90 seconds

62
Q

T/F absorbance is recorded at 27 seconds and again at 90 seconds during the BUN enzymatic reaction procedure

A

T

63
Q

Sequence: Prepare sample and reagent
1 Mix the solution by inverting the tubes 2-3 times
2 Set up the spectrophotometer at 340 nm.
3 Feed the solution into the spectrophotometer at 27 seconds and record absorbance as A1
4 Start incubation time
5 Add the reagent by touching the pipet to the side of the tube

A

2 5 1 4 3

64
Q

BUN Determination Assay requirements

Wavelength
Optical Path
Temperature

A

Wavelength: 340 nm
Optical path: 1 cm
Temperature: 37 ͦ C

65
Q

Urea Nitrogen Reference Intervals

Plasma or Serum

A

6-20 mg/dL [CU]
2.1-7.1 mmol/L [SI]

66
Q

Urea Nitrogen Reference Intervals

24-h Urine

A

12-20 g/day [CU]
0.43-0.71 mmol/day [SI]

67
Q

Clinical Significance

Elevated urea concentration in blood

A

Azotemia

68
Q

Clinical Significance

Increased urea level accompanied by renal failure

A

Uremia/Uremic Syndrome

69
Q

Range of Ellitrol Assayed Chemistry Control Level 1 Urease & Indophenol

A

Urease : 13.3-17.7
Indophenol : 28.5-37.9

70
Q

Range of Ellitrol Assayed Chemistry Control Level 2 Urease & Indophenol

A

Urease : 42.4-51.6
Indophenol : 90.7-111.0

71
Q

Formula for BUN determination

A

(A1-A2) sample/(A1-A2) standard x 50

72
Q

most widely used non-protein nitrogen compounds to assess renal function are __________ and __________

A

urea & creatinine

73
Q

T/F uric acid is used to diagnose disturbances in purine metabolism (eg. gouty arthritis)

A

T

74
Q

T/F: proteins are left in the specimen during the analysis of NPN compounds because they enhance the measurement.

A

F - removed because they interfere with analysis

75
Q

Select: Lowest Plasma Concentration

A. Creatinine
B. Uric acid
C. Ammonia
D. Urea

A

C - 0.2%

76
Q

C(BUN) = __________ x C(Urea).

A

0.466

77
Q

Select: Reference intervals for BUN in adults for plasma/serum
A. 4-15 mg/dL
B. 6-20 mg/dL
C. 2.1-7.1 mmol/L
D. 10-25 mg/dL

A

B & C

78
Q

Select: Post-renal increased plasma urea concentration

A. Urinary tract obstruction
B. Acute renal failure
C. Renal calculi
D. Tumor in the bladder

A

A C D

79
Q

T/F Low protein intake and severe vomiting can cause a decrease in plasma urea concentration

A

T

80
Q

Odd One Out: Pre-renal increased plasma urea concentration

A. Congestive heart failure
B. Renal disease
C. Dehydration
D. Shock

A

B - renal increased conc.

81
Q

OOO: Direct method for measuring urea

A. Involves heating the sample with diacetyl monoxime
B. Lacks sensitivity
C. Involves enzymatic digestion of urea
D. Time-consuming

A

C. Involves enzymatic digestion of urea - indirect

82
Q

indirect method for measuring urea involves digesting urea with the enzyme ___ to form ammonia, which is then measured

A

urease

83
Q

T/F BUN value is typically higher than the urea value

A

F - lower

84
Q

approximate BUN to urea ratio

A

1:2

[3Y1S] MT 6317 (4 decks)

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