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CC LEC > NPNs > Flashcards

NPNs Flashcards

1
Q

most abundant NPN (40%)

A

urea

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2
Q

excreted by the kidneys but 40% of them are reabsorbed

A

urea nitrogen (blood) BUN

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3
Q

major end product of protein and amino acid catabolism

A

urea nitrogen (blood) BUN

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4
Q

in urea nitrogen (blood) BUN, approximately ____ of the nitrogen excreted

A

80%

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5
Q

first metabolite to increase in kidney disease

A

urea nitrogen (blood) BUN

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6
Q

RV for urea nitrogen (blood) BUN

A

8-23 mg/dL (CF to mmol/L: 0.357)

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7
Q

normal bun:creatinine ratio

A

10-20:1

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8
Q

sample in urea nitrogen

A

serum, plasma, urine

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9
Q

(T/F)
BUN and urea are not exactly the same

A

true

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10
Q

only refer to nitrogen content of your urea

A

BUN

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11
Q

refer to the complete structure of urea

A

urea

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12
Q

(T/F)
refrigerate sample if delay in testing is expected. bacteria may decomposed urea and may decomposed by urease producing bacteria

A

true

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13
Q

(T/F)
assays for urea were based on measurement of nitrogen, hence the name blood urea nitrogen

A

true

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14
Q

3 methods in urea nitrogen

A
  1. chemical method
  2. enzymatic method
  3. isotope dilution mass spectrometry (reference method)
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15
Q

indicator dye in chemical method

A

diacetyl monoxime (DAM) method

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16
Q

reference method for urea nitrogen

A

isotope dilution mass spectrometry

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17
Q

end color in chemical method

A

yellow diazine derivative

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18
Q

atomic mass of nitrogen

A

14 g/mol

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19
Q

molecular mass of urea

A

60 g/mol

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20
Q

urea = ____ (____ of the total weight of urea)

A

2 nitrogen atoms (46.6%)

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21
Q

formula of urea to BUN

A

urea = BUN x 2.14

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22
Q

there is ____ of BUN per 60g/mol of urea

A

28 g/mol

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23
Q

for every 60 g/mol of urea, there is ____

A

28g/mol of nitrogen

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24
Q

for every BUN, there is _____ of urea

A

0.4666 g/mol

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25
Q

enzymatic methods (BUN)

A

urease method
urease glutamate dehydrogenase (GLD) method

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26
Q

it involves hydrolysis of urea to form ammonia by the enzyme urease

A

urease method

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27
Q

urease method end color

A

indophenol blue

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28
Q

ammonia and CO2 can be measured by different method to calculate the concentration of urea in the sample, however ____ is more commonly used.

A

ammonia

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29
Q

coupled urease method bc it uses 2 enzymes

UV enzymatic method

A

urea glutamate dehydrogenase (GLD) method

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30
Q

synthesized primarily by the liver from arginine, glycine, and methionine

A

creatinine

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31
Q

measures the completeness of 24hr urine collection

A

urine creatinine

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32
Q

urine creatinine = ____
incomplete = _____

A

> 0.8 g/day
<0.8

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33
Q

index of overall renal function bc it is very stable & always excreted in the urine and very small amount is reabsorbed

A

creatinine

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34
Q

RV for creatinine (male)

A

0.9 - 1.3 mg/dL

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35
Q

RV for creatinine (female)

A

0.6 - 1.1 mg/dL

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36
Q

RV for creatinine (child)

A

0.3 - 0.7 mg/dL

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37
Q

sample in creatinine

A

serum, plasma, urine

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38
Q

interferences in creatinine

A

hemolysis, ictericia, lipemia

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39
Q

4 methods in creatinine

A
  1. direct jaffe method (chemical method)
  2. kinetic jaffe method
  3. enzymatic method
  4. isotope dilution mass spectrometry (IDMS) - reference method
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40
Q

end color of direct jaffe method

A

red-orange (tantomer)

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41
Q

(T/F)
jaffe reagent is fairly unstable

A

true

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42
Q

components of jaffe reagent

A

saturated picric acid
10% NaOH

43
Q

if the two reagants of DJM is mixed together, it may form _____ and _____ which forms ____

A

picramic acid and methyl guanidine

orange color

44
Q

interferences in DJM

A

false increase:
creatinine-like analytes = uric acid, ascorbic acid, glucose, a-keto acids
medications = cephalosporins, dopamine, lidocaine

false decrease:
bilirubin, hemoglobin

45
Q

createinine-like analytes

A

uric acid, ascorbic acid, glucose, a-keto acids

46
Q

medications

A

cephalosporins
dopamine
lidocaine

47
Q

false decrease

A

bilirubin
hemoglobin

48
Q

2 methods in direct jaffe method

A

folin wu method
lloyd or fuller’s earth method

49
Q

a sensitive but not specific method

A

folin wu method

50
Q

interferences in folin wu method

A

creatinine-like substances/analytes:
acetoacetate
acetone
ascorbate
glucose
pyruvate

51
Q

(T/F)
to remove these interferences present normally in your specimen, we add _____

A

adsorbent

52
Q

a sensitive and specific method

A

lloyd or fuller’s earth method

53
Q

adsorbents in lloyd or fuller’s earth method

A

lloyd’s reagent
fuller earth’s reagent

54
Q

sodium aluminum silicate

A

lloyd’s reagent

55
Q

aluminum magnesium silicate

A

fuller’s earth method

56
Q

disadvantages of adsorbents

A

time consuming
not employed to automated analyzers

57
Q

requires automated analyzers for precision

A

kinetic jaffe method

58
Q

serum is mixed wuth alkaline picrate solution (picric acid + 10% NaOH) and the rate of change in absorbance is measured between two points

A

kinetic jaffe method

59
Q

interferences in kinetic jaffe method

A

false increased:
a-ketoglutarate
cephalosporins

60
Q

more specific than direct or kinetic jaffe method

used to eliminate the nonspecificity of the jaffe reaction/reagent

A

enzymatic method

61
Q

requires a large volume of pre-incubated sample therefore it is not widely used

A

creatinine aminohydrolase-CK method

62
Q

has potential to replace jaffe method bc it is more specific

without interference from acetoacetate and cephalosporins

A

creatinase-hydrogen peroxide method aka creatinine aminohydrolase

63
Q

creatinase-hydrogen peroxide method is also known as _____

A

creatinine aminohydrolase

64
Q

elevated concentration of NPN (urea & creatinine) in the blood

uremia/uremic syndrome (elevated urea + renal failure)

A

azotemia

65
Q

causes of urea plasma elevations are

A

prerenal
renal
postrenal

66
Q

reduced renal blood flow - less blood delivered to the kidney - less urea filtered

A

pre-renal azotemia

67
Q

causes of pre-renal azotemia

A

anything that produces a decrease in functional blood volume, include:
congestive heart failure
shock
hemorrhage
dehydration

high protein diet or increased catabolism:
fever
major illness
stress

68
Q

damaged kidneys - poor excretion - increased urea

A

renal azotemia

69
Q

true renal disease

A

renal azotemia

70
Q

causes of renal azotemia

A

acute/chronic renal disease
glomerulonephritis
tubular necrosis

71
Q

lab results in renal azotemia

A

BUN - increased (1st analyte to increase [>100 mg/dL])
creatinine - increased (200 mg/dL)
BUA - increased (12 mg/dL)
anemia - no EPO
electrolyte imbalance

72
Q

complications in renal azotemia

A

coma
neuropsychiatric changes

73
Q

usually the result of urinary tract obstruction

urea level is higher than creatinine due to back-diffusion of urea into the circulation

A

post renal azotemia

74
Q

causes of post renal azotemia

A

nephrolithiasis (kidney stones)
renal canaliculi
cancer/tumors of genitourinary tract
severe infection

75
Q

aka uric acid

A

2,6,8-trihydroxypurine

76
Q

major product of purine (AG) catabolism

final breakdown of nucleic acids catabolism in humans

A

uric acid

77
Q

uric acid is formed from _____ by the action of ______ in the liver and intestine

A

xanthine
xanthine oxidase

78
Q

uric acid is transported to kidney and filtered

A

70%

79
Q

___ is reabosorbed by PCT & some are secreted by the DCT into the urine

A

98%

80
Q

remaining ___ by GIT degraded by bacterial enzymes

A

30%

81
Q

sources of uric acid

A
  1. ingested/food intake - nucleoproteins from food
  2. endogenous
  3. direct transformation of endogenous purine nucleotides
82
Q

uric acid is present in plasma as _____

A

monosodium urate (95%)

83
Q

____ of uric acid is excreted by the kidney

A

70%

84
Q

pH of monosodium urate

A

pH 7 (normal blood pH)

85
Q

if urine filtrate is acidic (pH <5.75), it may form _____ in urine

A

urine acid crystals

86
Q

RV for uric acid (male)

A

3.5 - 7.2 mg/dL

87
Q

RV for uric acid (female)

A

2.6 - 6.0 mg/dL

88
Q

RV for uric acid (child)

A

2.0 - 5.5 mg/dL

89
Q

saturated plasma with uric acid

A

> 6.8 mg/dL

90
Q

uric acid sample

A

serum
heparinized plasma
urine

91
Q

in uric acid, serum may be stored for _____ (ref)

A

3-5 days

92
Q

urine sample for uric acid

A

pH 8.0

93
Q

interferences in uric acid

A

false increased: lipemia, salicylates, thiazides

false decreased: high bilirubin, hemolysis

94
Q

3 methods in uric acid

A
  1. chemical methods
  2. enzymatic method
  3. isotope dilution mass spectrometry (reference method)
95
Q

aka caraway method
reduction-oxidation reaction

A

chemical method

96
Q

end color of caraway method

A

tungsten blue

97
Q

sodium cyanide (NaCN)

A

folin, newton, brown, benedict

98
Q

sodium carbonate (NaCO3)

A

caraway, archibald, henry

99
Q

uricase method
specific method

A

enzymatic method

100
Q

what tubes are not used in enzymatic method?

A

EDTA
fluoride tube

101
Q

peak absorbance at 293 nm

A

uric acid

102
Q

not absorbed at 293 nm

A

allantoin

103
Q
  1. gout
  2. increased nuclear metabolism
  3. chronic renal disease
  4. lesch-nyhan syndrome
  5. secondary to GSD
  6. toxemia of pregnancy and lactic acidosis
  7. increased dietary intake
  8. ethanol consumption
A

hyperuricemia

104
Q
  1. fanconi’s syndrome
  2. wilson’s disease
  3. hodgkin’s disease
  4. overtreatment with allopurinol
  5. chemotherapy (6-mercaptopurine, azathioprine)
  6. alzheimer’s disease
  7. parkinson’s disease
A

hypouricemia

CC LEC (2 decks)

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