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MT6317 CLIN CHEM 1 > U4 LEC: NPNs: UREA (PT. 1) > Flashcards

U4 LEC: NPNs: UREA (PT. 1) Flashcards

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1
Q

These are nitrogen containing substances found in blood that are not proteins

A

Nonprotein Nitrogen Compounds

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2
Q

NPNs are used for the?

A

assessment and monitoring of renal function

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3
Q

NPNs are considered as?

A

waste products

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4
Q

Historically, nitrogen content was measured with?

A

removal of proteins

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5
Q

Specimen used in historical methods for NPN

A

Protein Free Filtrate

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6
Q

Clinically significant NPNs

A
  • Urea / BUN
  • Amino acids
  • Uric Acid
  • Creatinine
  • Creatine
  • Ammonia
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7
Q

Concentration in Plasma and Urine

Urea

A

P: 45-50%
U: 86%

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8
Q

Concentration in Plasma and Urine

Amino acids

A

P: 25%

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9
Q

Concentration in Plasma and Urine

Uric Acid

A

P: 10%
U: 1.7%

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10
Q

Concentration in Plasma and Urine

Creatinine

A

P: 5%
U: 4.5%

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11
Q

Concentration in Plasma and Urine

Creatinine

A

P: 1-2%

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12
Q

Concentration in Plasma and Urine

Ammonia

A

P: 0.2%
U: 2.8%

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13
Q

This NPN should not be present in the bloodstream as it can go up to the brain and become neurotoxic.

A

Ammonia

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14
Q

NPNs not present in Urine

A
  • Amino acids (repurposed)
  • Creatine
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15
Q

This is the major excretory product from protein metabolism, and is the major NPN found in the blood.

A

Urea

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16
Q

The amino acid from protein metabolism will enter 3 pathways which are?

A
  • for energy
  • entering the urea cycle
  • for another amino acid
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17
Q

Synthesis of Urea happens where?

A

liver

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18
Q

When does urea synthesis start?

A

after digestion of protein > ammonium is made > enters liver for conversion to urea

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19
Q

The Urea Cycle is also known as the?

A

Krebs Henseleit Cycle

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20
Q

The Urea Cycle takes place in?

A

hepatocytes

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21
Q

Urea Cycle

Primary Function

A

conversion of ammonium ions to urea in liver/hepatocyte for excretion by kidney

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22
Q

The Urea Cycle is a _________ process between the?

A

compartmentalized, mitochondria and cytosol

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23
Q

Urea Cycle

This starts when amino acid from ____________ generated in protein metabolism binds with?

A

ammonia, CO2

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24
Q

Urea Cycle

Ammonia first enters the?

A

mitochondria of hepatocyte

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25
Q

This enzyme converts ammonia to carbamoyl phosphate.

A

CPS1

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26
Q

CPS1 stands for?

A

Carbamoyl Phosphate Synthetase 1

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27
Q

Urea Cycle

This is considered the first step. This enters the cycle and eventually becomes Urea.

A

Carbamoyl Phosphate

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28
Q

Urea Cycle

Carbamoyl phosphate is converted into citrulline by the enzyme?

A

Ornithine Transcarbomylase (OTC)

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29
Q

Urea Cycle

OTC stands for?

A

Ornithine Transcarbomylase

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30
Q

Urea Cycle

Products of OTC

A

Citrulline, Inorganic phosphate

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31
Q

Urea Cycle

Citrulline will enter?

A

cytoplasm/cytosol

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32
Q

Urea Cycle

This enzyme converts Citrulline to Arginosuccinate.

A

Arginosuccinate Synthetase

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33
Q

Urea Cycle

Citrulline is converted to?

A

Arginosuccinate

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34
Q

Urea Cycle

Arginosuccinate meets what enzyme to release Arginine and Fumarate?

A

Arginosuccinate lyase

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35
Q

Urea Cycle

Arginosuccinate lyase produces?

A

Arginine and Fumarate

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36
Q

Urea Cycle

Arginine will meet what enzyme for conversion to Ornithine?

A

Arginase

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37
Q

Urea Cycle

What will be formed during conversion of Arginine to Ornithine by Arginase?

A

Urea

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38
Q

What is increased (↑) if there is non production of urea?

A

(↑) Ammonia

(kasi di siya nacconvert to urea)

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39
Q

T/F: Any enzyme deficiency concerning the urea cycle will result to non production of urea.

A

True

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40
Q

Urea is filtered by?

A

glomerulus

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41
Q

Parts of the Nephron that contains Urea

A
  • Proximal convoluted tubules
  • Loop of Henle
  • Collecting tubules
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42
Q

Exit from nephron (palabas) will be brought back to?

A

capillary (bloodstream)

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43
Q

Entry to nephron will be brought to?

A

urine

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44
Q

Urea is reabsorbed in the?

A

proximal convoluted tubules

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45
Q

Percent of Urea that is reabsorbed

A

40%

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46
Q

Percent of Urea excreted in urine

A

50%

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47
Q

Percent of Urea excreted in GI tract (stool) or skin perspiration (Sweat)

A

< 10%

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48
Q

Concentration of urea is dependent on?

A
  1. renal function / perfusion
  2. protein content of diet
  3. amount of protein metabolism (madami kang kinakain but can it convert to urea)
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49
Q

Why do we need to reabsorb Urea back in blood?

A

maintain balance in content or osmolality of blood if dehydrated (konting fluid, need may ibalik na salt or compound)

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50
Q

T/F: Urea is different from Urea nitrogen (Urea N) and BUN in terms.

A

True

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51
Q

1 mmol N is equal to?

A

14mg N

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52
Q

1 mmol Urea is equal to how many mmol of N?

A

2 mmol N

53
Q

1 mmol Urea is equal to how many mg of Urea?

A

60 mg Urea

54
Q

1 mg/dL BUN is equal to how many mg/dL of Urea?

A

2.14 mg/dL Urea

55
Q

Conversion Factor of BUN to Urea

A

2.14

56
Q

Clinical application

Excretion and reabsorption

A

Evaluate renal function

57
Q

Clinical application

Increased urea in blood might pose a problem in the?

A

glomerulus

58
Q

Clinical application

Decreased urea levels can indicate?

A

no reabsorption in the nephron

59
Q

Clinical application

This refers to how levels of Urea will depend on blood volume

A

Hydration status

60
Q

Clinical application

Diluted masyado, decreased (↓) urea levels

A

Overhydrated

61
Q

Clinical application

(↑) Increased urea levels

A

Dehydrated

62
Q

Clinical application

Representation of Nitrogen compound

A

Assess Nitrogen Balance

63
Q

Clinical application

This machine works as your new kidneys

A

Verify adequacy of dialysis

64
Q

Elevated concentration in the blood but asymptomatic or no problems in kidney (early pa)

A

Azotemia

65
Q

Symptomatic, very high levels of plasma urea accompanied by renal failure

A

Uremia / Uremic Syndrome

66
Q

Treatment for Uremia

A

dialysis or kidney transplant

67
Q

In Azotemia, levels of _____ are also being measured along with BUN

A

Creatinine

68
Q

Under pre-renal

A

Impaired perfusion:
- Cardiac failure
- Sepsis
- Blood loss
- Dehydration
- Vascular occlusion

69
Q

Under renal

A
  • Glomerulonephritis
  • Small-vessel vasculitis
  • Acute tubular necrosis (Drugs, Toxins, Prolonged hypotension)
  • Interstitial nephritis (Drugs, Toxins, Inflammatory disease, Infection)
70
Q

Under Post-Renal

A
  • Urinary calculi
  • Retroperitoneal fibrosis
  • Benign prostatic enlargement
  • Prostate cancer
  • Cervical cancer
  • Urethral structure/valves
  • Meatal stenosis/phimosis
71
Q

Pathophysiology of Pre-renal Azotemia

A

reduction in blood flow to kidney / decreased blood flow to kidney

72
Q

Examples of decreased blood flow to kidneys (Pre-renal)

A
  • Congestive heart failure
  • Shock
  • Hemorrhage
  • Dehydration (no fluid, wala ring ippump)
73
Q

Other causes of Pre-renal Azotemia

A

level of protein metabolism

74
Q

Conditions of other causes of Pre-renal Azotemia

A
  • High protein diet

Increased protein catabolism
Fever
- Major illness
- Stress
- Burns
- Corticosteroid therapy
- GI bleeding

75
Q

Pathophysiology of Renal Azotemia

A
  • Acute/chronic Renal failure
  • Glomerulonephritis
  • Tubular necrosis
  • Other intrinsic renal disease
76
Q

Renal Azotemia

Problem in the filter

A

Glomerulus

77
Q

Renal Azotemia

Problem in the tubules, not capable of reabsorption

A

Tubular necrosis

78
Q

Conversion from azotemia to uremia is focused on?

A

Renal azotemia

79
Q

Post-renal Azotemia refers to?

A

Urinary tract obstruction

80
Q

Causes of Post-renal Azotemia / Obstruction

A

1.) renal calculi or kidney stones
2.) tumors (prostate / bladder)

81
Q

The types of Azotemia can be distinguished by computing for the?

A

Urea Nitrogen : Creatinine Ratio

82
Q

Normal N:C ratio

A

10:1 - 20:1

83
Q

Normal BUN in Conventional Unit

A

6-20 mg/dL

84
Q

Increase in urea

A

> 20

85
Q

Normal Creatinine

A

1.5 mg/dL

86
Q

T/F: Creatinine has to be excreted, no reabsorption occurs.

A

True

87
Q

Urea Nitrogen and Creatinine

Pre-renal Azotemia

A

High urea (decreased blood flow)
Normal creatinine
ELEVATED RATIO

88
Q

Urea Nitrogen and Creatinine

Renal Azotemia

A

High urea
High creatinine
ELEVATED/NORMAL RATIO

89
Q

Urea Nitrogen and Creatinine

Post-Renal Azotemia

A

Normal (?, dapat high) urea
High creatinine
ELEVATED RATIO

90
Q

T/F: In renal azotemia, there is a proportional increase for both urea and creatinine.

A

True

91
Q

T/F: Urea in Post-Renal Azotemia can also be high.

A

True

92
Q

This is a marker of kidney filtration.

A

Creatinine

93
Q

Conditions with decreased levels of plasma urea and decreased N:C ratio

A
  • decreased protein intake
  • poor nutrition
  • overhydration
  • severe liver disease (cannot synthesize ammonia)
  • severe vomiting and diarrhea (GI tract)
  • increased protein synthesis (recycled to make another protein)
94
Q

Measures urea as a whole

A

Direct method

95
Q

Measures only nitrogen content of Urea

A

Indirect method

96
Q

Conversion Factor of Urea to BUN

A

0.467

97
Q

BUN Conventional to BUN SI Unit

A

0.357

98
Q

6-20mg/dL is equal to what SI unit of BUN?

A

2.1 - 7.1 mmol/L

99
Q

Urea Determination

Condensation with Diacetyl Monoxime Method

A

Fearon’s Reaction

100
Q

Urea Determination

Fearon’s Reaction is also known as?

A

Friedman’s Method or Xanthydrol Method

101
Q

Fearon’s Reaction

Reagents

A

strong acid, oxidizing agent, ferric ions, thiosemicarbazide

102
Q

Fearon’s Reaction

Product

A

Yellow diazine derivative (Ferric)

103
Q

Fearon’s Reaction

Advantages

A
  • Ammonia does not interfere
  • Used in autoanalyzers
104
Q

Fearon’s Reaction

Disadvantages

A
  • non specific
  • uses toxic substances
105
Q

Fearon’s Reaction

DAM with water produces?

A

diacetyl and H+

106
Q

Urea Determination

Reaction with o-phtalaldehyde and napthylethylene will produce?

A

chromogen or colored product

107
Q

Reaction with o-phtalaldehyde and napthylethylene

Reagents

A

Isoindoline and napthylethylene diamine

108
Q

Reaction with o-phtalaldehyde and napthylethylene

Advantages

A
  • No ammonia interference
  • Used in automation (spectrophotometry)
109
Q

Reaction with o-phtalaldehyde and napthylethylene

Disadvantage

A

sulfa containing drugs interfere

110
Q

This method also produces yellow product, converting ammonium to ammonia.

A

Micro-Kjeldahl Nessler Method

111
Q

Enzymatic methods utilizes?

A

Urease

112
Q

Enzymatic Methods

This method utilizes the Nessler’s Reagent to form yellow product.

A

Urease-Nessler’s Method

113
Q

Enzymatic Methods

This uses phenol hypochlorite to release product that is indophenol blue.

A

Urease-Berthelot’s Method

114
Q

Urease-Berthelot’s Method

Disadvantages

A
  • non specific (since it is a measure of ammonia)
  • very sensitive to interference from endogenous NH3
115
Q

Enzymatic Methods

Most common

A

Urease-L-Glutamate Dehydrogenase (GLDH) Method

116
Q

GLDH Method

Coupling reaction with what enzyme, and releases what products?

A

GLDH, 2-oxoglutarate to glutamate

117
Q

GLDH Method

Measures the?

A

reduction of NADH to NAD

118
Q

T/F: Disappearance of NADH is proportional to Urea levels.

A

True

119
Q

Enzymatic Methods

Conductivity of ammonium is measured

A

Urease-Conductimetric Method

120
Q

Proposed Reference Method

A

Isotope Dilution Mass Spectrophotometry (IDMS)

121
Q

Specimen Requirements for BUN

Refrain tubes that have?

A
  • Sodium citrate
  • Sodium fluoride
122
Q

Action of Na Citrate and NaF

A

inhibits urease

123
Q

Urea is susceptible to _______, which results in urea converted back to ammonia

A

bacterial decomposition

124
Q

Bacteria in urine can cause?

A

ammoniacal odor / mapanghi (increased ammonia)

125
Q

Urine sample should be?

A

refrigerated

126
Q

T/F: Diet influence or no fasting requirement will not affect BUN.

A

True

pwede daw sya maginfluence pero hindi agad agad

127
Q

Urine should be collected for?

A

24 hours

128
Q

Urea Nitrogen in Urine

A

12-20 g/dL (0.43-0.71 mol urea/d)

MT6317 CLIN CHEM 1 (11 decks)

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