NPN Compounds and Kidney Function Tests Flashcards

1
Q

2 regions of the kidney

A

renal cortex (outer), renal medulla (inner)

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2
Q

functional unit of kidney

A

nephron

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3
Q

stimulates bone marrow to produce RBCs

A

erythropoietin

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4
Q

bean shaped located on either side of

A

spinal column

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5
Q

main function of kidneys

A

urine formation and excretion of waste products

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6
Q

adrenal glands secretes

A

aldosterone & vasopressin

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7
Q

prevents water loss and is also known as

A

vasopressin, anti-diuretic hormone

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8
Q

regulates water and salt in the body

A

aldosterone

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9
Q

parts of nephrons

A

PCT, DCT, loop of henle, glomerulus, collecting duct

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9
Q

promotes reabsorption of sodium and excretion of potassium

A

aldosterone

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10
Q

function of PCT

A

reabsorbs Na, Cl, HCO3-, Glucose, Amino acids, Proteins, Urea, & Uric acid

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11
Q

function of collecting duct

A

final site for concentration or dilution of urine

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12
Q

function of loop henle

A

site of major exchange of water and salt

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13
Q

NPN Compounds %

A

urea - 45%
uric acid - 20%
creatine - 1-2%
amino acid - 20%
creatinine - 5%
ammonia - 0.2%

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14
Q

plasma contain _ of NPN compound

A

20-35 mg/dL

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15
Q

ammonia is detoxified in the _ to produce _

A

liver, urea

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16
Q

most abundant NPN

A

urea

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17
Q

ammonia exist as _ in normal blood pH

A

ammonium ions

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18
Q

acute metabolic disorder of the liver & common in children

A

Reye’s syndrome

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19
Q

normal BUN-creatinine ratio

A

10:1 - 20:1

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20
Q

Major end product of protein and amino acid catabolism

A

BUN

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21
Q

Easily removed by dialysis

A

BUN

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22
Q

In BUN, approximately ____ of the nitrogen is excreted

A

80%

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23
Q

In BUN, Formed through the ______ in the liver

A

Krebs-Henseleit (Urea) cycle

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24
Q

Excreted by the kidneys – ___ reabsorbed
___ of the total are excreted through the gastrointestinal tract and skin.

A

40% , <10%

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25
Q

Clinical application of BUN measurement

A
  • Evaluate renal function
  • Assess dehydration status
  • Determine the nitrogen balance in the body
  • Aid in the diagnosis of renal disease
  • Verify the efficacy of dialysis
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26
Q

In BUN, Concentration is determined by

A
  • Renal function
  • Dietary intake
  • Protein catabolism rate
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27
Q

End (waste) product of muscle metabolism derived from creatine and creatine phosphate

A

creatinine

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28
Q

Creatine is converted to creatinine through_____

A

dehydration

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29
Q

Creatine phosphate is converted to creatinine through ____

A

dephosphorylation

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30
Q

Creatine is phosphorylated to creatine phosphate by the presence of _____

A

creatine kinase

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31
Q

Creatinine is synthesized primarily by the liver from ____

A

arginine, glycine and methionine

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32
Q

Partially secreted by the proximal tubules via the organic cation transport pathway

A

creatinine

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33
Q

Not easily removed by dialysis

A

creatinine

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34
Q

Not reabsorbed by the tubules

A

creatinine

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35
Q

Measure the completeness of 24 hour urine collection (urine creatinine).

A

creatinine

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36
Q

Index of overall renal function

A

creatinine

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37
Q

Elevated creatinine is found in ____

A

abnormal renal function

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38
Q

creatinine measurement

A
  • Sufficiency of kidney function
  • Severity of kidney damage
  • Monitor progression of kidney disease
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39
Q

In Acute Kidney Injury, functional or structural abnormalities or markers of kidney damage (seen in blood, urine, tissue test, imaging studies) present for___

A

3 months

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40
Q

stage 1 creatinine

A

SCC = >0.3 mg/dL or 150-200%
UOC = <0.5 mL/kg for >6hr

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41
Q

Heating converts creatine to creatinine and the difference between the two samples is the _______.

A

creatine concentration

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41
Q

stage 2 creatinine

A

SCC = >200 - 300%
UOC = <0.5 mL/kg for >12hr

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42
Q

stage 3 creatinine

A

SCC = >300%, 4 mg/dL or acute increase of >0.5 mg/dL
UOC = <0.3 mL/kg for >24hr or anuria of >12hr

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43
Q

Specialized test, not part of routine testing

A

Creatine

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44
Q

In Creatine, Analyzing the sample for creatinine before and after heating in acid solution using an endpoint _____.

A

Jaffe method

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45
Q

Elevated in plasma and urine in

A

Muscular dystrophy, hyperthyroidism, trauma.

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46
Q

Increased concentration of BUN and Creatinine in the blood

A

Azotemia

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47
Q

elevated plasma urea concentration accompanied by renal failure

A

Uremia/Uremic syndrome

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48
Q

Reduced Renal Blood Flow

A

pre renal azotemia

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49
Q

Less blood delivered to the kidney

A

pre renal azotemia

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50
Q

Less Urea filtered

A

pre renal azotemia

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51
Q

causes of pre renal azotemia

A

Congestive heart failure
Shock
Hemorrhage
Dehydration
High protein diet or increase catabolism

52
Q

True renal disease

A

renal azotemia

53
Q

Characterized by damage within the kidney

A

renal azotemia

54
Q

Damaged kidneys

A

renal azotemia

55
Q

Poor excretion

A

renal azotemia

56
Q

Increased Urea

A

renal azotemia

57
Q

complication of renal azotemia

A

Coma or neuropsychiatric changes

58
Q

In renal azotemia, BUN will have an ____ of _____

A

abrupt elevation, >100 mg/dL

59
Q

In renal azotemia, Creatinine will have a ____ of ___

A

slow elevation, 20 mg/dL

60
Q

In renal azotemia, BUA (Blood Uric Acid) =

A

12 mg/dL

61
Q

No erythropoietin will be secreted

A

renal azotemia

62
Q

Associated with anemia and electrolyte imbalance due to reabsorption capacity impairment

A

renal azotemia

63
Q

Usually the result of Urinary Tract Obstruction

A

post renal azotemia

64
Q

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

A

post renal azotemia

65
Q

It is the major product of purine (adenine and guanine) catabolism.

A

uric acid

66
Q

It is formed from xanthine by the action of xanthine oxidase in the liver and intestine.

A

uric acid

67
Q

Uric acid is transported to kidney and filtered (___)

A

70%

68
Q

1g of uric acid is excreted normally and 98% is reabsorbed in the ___ and ____

A

PCT & DCT

69
Q

Uric acid is in the form of ______() in plasma

A

monosodium urease (95%)

70
Q

Pain & inflammation of joints by precipitation of sodium urates in tissues

A

gout

71
Q

When value is _____, uric acid crystals may form and precipitate in the tissues and contribute to formation of gout and stones in the kidney

A

> 6.8 mg/dL

72
Q

Primarily seen in men and first diagnosed between 30-50 of age

A

gout

73
Q

presence of “birefringent crystal in synovial fluid”

A

gout

74
Q

Increased risk of renal calculi/nephrolithiasis

A

gout

74
Q

Gout causes ___ increase of uric acid

A

25-30%

75
Q

Occurs in patients on chemotherapy for diseases such as leukemia & multiple myeloma.

A

Increased Nuclear Metabolism

76
Q

Causes elevated levels of uric acid because filtration and secretion are hindered.

A

Chronic renal disease

76
Q

In Increased Nuclear Metabolism, Allopurinol inhibits ____, an enzyme in the uric acid synthesis pathway, which is used to treat these patients.

A

xanthine oxidase

77
Q

In Chronic renal disease, BUA is

A

> 10 mg/dL

78
Q

Can cause urinary tract calculi

A

Chronic renal disease

79
Q

Inborn error of purine metabolism

A

Lesch-Nyhan Syndrome

80
Q

In Lesch-Nyhan Syndrome, It is deficient of

A

hypoxanthine-guanine phosphoribosyl transferase (HGPRT)

81
Q

other causes of Lesch-Nyhan Syndrome

A

Secondary to glycogen storage disease
Toxemia of pregnancy and lactic acidosis
Increased dietary intake
Ethanol consumption

82
Q

Best overall indicator of the level of kidney function

A

GFR

82
Q

Disorder of reabsorption in the PCT of the kidney

A

fanconi’s syndrome

83
Q

6-mercaptopurine, azathioprine

A

Chemotherapy

84
Q

Measures the clearance of substances not bound to protein.

A

GFR

85
Q

GFR decreased by 1.0 mL/minute/year after age ___ years.

A

20-30

86
Q

In GFR, _____of glomerular filtrate is produced daily.

A

150L

87
Q

In GFR, About ___ of water is filtered daily

A

180L

88
Q

In GFR, ___ is reabsorbed in the PCT

A

150L

89
Q

In GFR, ___ in the descending loop of henle of cortical nephrons

A

5L

90
Q

Removal of the substance from plasma into urine over a fixed time (24hrs).

A

clearance

91
Q

In Clearance, Plasma concentration is _____ to clearance

A

inversely proportional

92
Q

In Clearance, formula is affected by ______ and correction for _____should be included in the formula

A

body surface area, body mass

93
Q

Reference method of clearance test

A

inulin clearance test

94
Q

exogenous substance (never produced by the body)

A

inulin clearance test

95
Q

Introduced via IV (____mL of ___% inulin soln.)

A

inulin clearance test, 500 , 1.5

96
Q

Not routinely done due to the necessity for continuous IV inclusion

A

inulin clearance test

97
Q

Alternatives to Inulin

A

Radioactive marker: 125I-iothalamate & 99mTc-DTPA
Iohexol and Chromium 51-labelled EDTA
Nonradiolabeled iothalamate

98
Q

Best alternative method to inulin

A

Creatinine clearance

99
Q

Excellent measure of renal function

A

Creatinine clearance

100
Q

endogenous substance freely filtered by the glomeruli but not reabsorbed.

A

Creatinine

101
Q

Production & excretion of creatinine are directly related to

A

muscle mass

102
Q

Excretion is not routinely affected by diet

A

creatinine clearance

103
Q

In creatinine clearance, Approximately ___of creatinine is excreted per day

A

1.2-1.5 g

104
Q

Major limitation of creatinine clearance

A

urine collection should be accurate (timing)

104
Q

Demonstrate progression of renal disease or response to therapy

A

Urea clearance

105
Q

Not reliable GFR – urea is freely filtered but variably reabsorbed by the tubules

A

Urea clearance

106
Q

Low molecular weight protease inhibitor and produced at a constant rate by all nucleated cells.

A

Cystatin C

107
Q

Indirect estimate of GFR

A

Cystatin C

108
Q

Freely filtered by the glomerulus but completely reabsorbed by the tubules

A

Cystatin C

109
Q

Presence of Cystatin C in urine denotes that there is a damage in the

A

PCT

110
Q

Only kidney function test that should not be measured in urine.

A

Cystatin C

111
Q

Not affected by muscle mass, age, diet, and gender

A

Cystatin C

112
Q

AKA Prostaglandin D synthase

A

BTP

113
Q

A low molecular weight glycoprotein (____amino acid)

A

BTP, 168

114
Q

Belongs to the lipocalin protein family

A

BTP

115
Q

Isolated primarily from CSF

A

BTP

116
Q

Accurate marker for CSF leakage

A

BTP

117
Q

Freely filtered by the glomerulus but completely reabsorbed and catabolized by the proximal tubule.

A

BTP

118
Q

BTP in serum correlates significantly with ___. However, BTP is ___ diagnostic efficient test for GFR.

A

serum Cystatin C, GFR, urine microproteins // not a

118
Q

Increased in B-trace protein

A

Renal disease (because of reduced filtration in the presence of constant production)

119
Q

In clearance, time required to collect urine

A

1440 minutes

120
Q

In clearance, ave. body surface of adult individual (___ for pediatric)

A

1.73, 0.717

121
Q

Uric acid is measured to:

A

assess inherited disorders of purine metabolism
to confirm diagnosis and monitor treatment of gout
to assist in the diagnosis of renal calculi
to prevent uric acid nephropathy during chemotherapeutic treatment
and to detect kidney dysfunction

122
Q

In Creatine, Elevated in plasma and urine in

A

Muscular dystrophy, hyperthyroidism, trauma.

123
Q

Plasma creatinine concentration is a function of:

A

relative muscle mass
rate of creatine turnover
and renal function