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MT6317 > UNIT X: Urea Nitrogen Determination > Flashcards

UNIT X: Urea Nitrogen Determination Flashcards

1
Q

Major excretory product of protein metabolism

A

Urea

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2
Q

T or F: Urea is formed in the kidney

A

F

Liver

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3
Q

Urea is also known as

A

Carbamide

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4
Q

Chemical formula of urea

A

CO(NH2)2

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5
Q

T or F: Urea has 2 -NH2 groups joined by a carbonyl functional group

A

T

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6
Q

T or F: Urea determination is also known as Blood Urea Nitrogen

A

T

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7
Q

Urea determination is a common blood chemistry test ordered by physicians to assess renal function, together with ______ (another NPN)

A

creatinine

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8
Q

Enzymatic method uses this enzyme

A

Urease or Urea Amidohydrolase

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9
Q

Most frequently used method in clinical laboratories

A

Enzymatic method

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10
Q

T or F: Enzymatic method allows the hydrolysis of urea in the sample, and the ammonium ion (NH4+) produced in the reaction is quantified

A

T

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11
Q

Most common enzymatic method

A

GLDH

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12
Q

GLDH stands for

A

Glutamate dehydrogenase

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13
Q

Indicator dye measures urea by ______ ______ using a pH indicator

A

color change

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14
Q

T or F: GLDH uses liquid reagents, multilayer film formats, and reagent strips

A

F

Indicator Dye uses these

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15
Q

Conductimetric method uses an ________ to measure the rate of increase in conductivity

A

electrode

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16
Q

This is the reference method

A

IDMS

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17
Q

IDMS uses ________-labeled compounds for quantification

A

isotopically

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18
Q

IDMS stands for

A

Isotope Dilution Mass Spectrometry

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19
Q

Direct/Indirect: Measures a chromogen produced directly from Urea

A

Direct

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20
Q

Direct/Indirect: Involves heating he sample with diacetyl monoxime in acidic solution

A

Direct

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21
Q

Direct/Indirect: Involves digesting the urea with urease to form ammonia

A

Indirect

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22
Q

Direct/Indirect: Lacks sensitivity, is time-consuming and hazardous

A

Direct

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23
Q

T or F: GLDH is an example of a Direct method

A

F

Indirect

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24
Q

T or F: Only the nitrogen part of Urea is quantitated in BUN

A

T

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25
Q

The biosynthesis of urea from ammonia is exclusively carried out by the _________ ________

A

hepatic enzymes

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26
Q

___% of urea is reabsorbed

A

40

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27
Q

Principle behind Urease/GLDH Method

A

Enzymatic + UV + Kinetic

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28
Q

T or F: In GLDH Method, absorbance is read twice

A

T

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29
Q

T or F: Decrease in absorbance at 430 nm is proportional to the concentration of Urea

A

F

340 nm

30
Q

Urease hydrolyzes Urea to form _______ and ______

A

ammonia ; carbonate

31
Q

Glutamate dehydrogenase forms these 3 products

A

Glutamate, NAD, and water

32
Q

In GLDH method, ________ and _______ are converted to glutamate

A

ammonia ; a-oxoglutarate

33
Q

T or F: The oxidation of NADH to NAD+ causes a decrease in absorbance in the reaction

A

T

34
Q

This method is best used as a kinetic measurement

A

GLDH

35
Q

This method is the most specific and rapid

A

Conductometric

36
Q

Specimen used in Urea determination (3)

A

Serum
Plasma
Timed Urine Specimen

37
Q

These additives should be avoided if plasma is collected for Urea determination

A

Sodium citrate
Sodium fluoride

38
Q

T or F: Urine is stable up to 5 days if stored at 2-8C

A

F

4 days only

39
Q

Sodium citrate and sodium fluoride are inhibitors of ______

A

urease

40
Q

T or F: Fasting is required in Urea determination

A

F

41
Q

Reagent 1

A

Tris buffer (7.6)
ADP
alpha-ketoglutarate
urease
glutamate dehydrogenase
sodium azide

42
Q

Reagent 2

A

NADH
sodium azide

43
Q

T or F: Sodium azide irritates eyes and skin

A

T

44
Q

Concentration of Standard Urea

A

50 mg/dL or 8.33 mmol/L

45
Q

T or F: Lithium heparinized plasma can be used

A

T

46
Q

Ellitrol I is the _______ Control; while Ellitrol II is the _______ Control

A

Normal ; Pathologic

47
Q

Type of test tube to be used

A

Kahn test tube

48
Q

Ratio of R1 to R2

A

1:1

49
Q

Volume of Reagent 1A

A

1.0 mL

50
Q

T or F: Reagent is added to the test tubes before the sample

A

F

Sample first

51
Q

T or F: When delivering the sample, touch the pipet directly to the bottom of the tube

A

T

52
Q

T or F: Spectrophotometer is set up prior to adding the sample to the test tube

A

F

after adding the sample and prior to adding the reagent

53
Q

T or F: When delivering the reagent, touch the pipet directly to the bottom of the tube

A

F

only to the side of the tube

54
Q

Cover the test tube with parafilm and invert the tubes _____ times

A

2-3

55
Q

Read and record the absorbance as A1 at ___ seconds

A

27

56
Q

Read and record the absorbance as A2 at ___ seconds

A

90

57
Q

Wavelength required

A

340 nm

58
Q

Optical path required

A

1 cm

59
Q

Temperature required

A

37 C

60
Q

Assay should be read against ________ ______

A

distilled water

61
Q

Formula for the change in absorbance

A

A1 - A2

62
Q

T or F: BUN value is higher than Urea value

A

F

lower (1:2)

63
Q

Conversion factor for Urea mg/dL to BUN mg/dL

A

0.466

64
Q

Conversion factor for BUN mg/dL to Urea mg/dL

A

2.14

65
Q

Conversion factor for BUN mg/dL to Urea mmol/L

A

0.357

66
Q

Reference interval for Plasma or Serum

A

Conventional: 6-20 mg/dL
SI: 2.1-7.1 mmol/L

67
Q

Reference interval for 24-hr urine

A

Conventional: 12-20 g/day
SI: 0.43-0.71 mmol/day

68
Q

Elevated urea concentration in blood

A

Azotemia

69
Q

Uremia / Uremic Syndrome

A

Increased urea level accompanied by renal failure

70
Q

T or F: Severe diarrhea can cause a decrease in the concentration of Urea

A

T

71
Q

Range for normal control

A

13.3 - 17.7 mg/dL

72
Q

Range for abnormal control

A

42.4 - 51.6 mg/dL

MT6317 (2 decks)

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