Kidney function test Flashcards

References: Book ni Dean Rodriguez sa CC Trans ni Rovie Vila

1
Q

It is paired, bean-shaped organs located retroperitoneally on either side of the spinal column

A

Kidney

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2
Q

Outer region of the kidney

A

Cortex

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3
Q

Inner region of the kidney

A

medulla

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4
Q

functional and structural unit of the kidney

A

Nephron

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5
Q

What are the 5 basic parts of the nephron

A
  • Renal Corpuscle (Glomerulus)
  • Loop of Henle
  • Proximal Convoluted Tubule (PCT)
  • Distal Convoluted Tubule (DCT)
  • Collecting Duct
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6
Q

Filtering unit or part of the kidney, retaining large proteins and protein-bound constituents while most other plasma should be approximately equal to ECF without protein

A

Renal Corpuscle (Glomerulus)

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7
Q

Cells in Bowman’s capsule in the kidneys

A

podocytes

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8
Q

Expanded end of a renal tubule

A

Bowman’s capsule

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9
Q

composed of the thin descending limb, which spans the medulla, and the ascending limb, which is located in both the medulla and the cortex
- highest osmolarity in the nephron
- enables water reabsorption to be increased or decreased in response to body fluid changes in osmolality

A

loop of Henle

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10
Q

all parts of kidney are permeable except

A

ascending loop

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11
Q

Glomerular filtrate =

A

1.000 - 1.010 (Isosthenuric)

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12
Q

It is responsible for the reabsorption of Sodium, Amino acids, Glucose, Urea, Water (SAGUW)

A

Proximal Convoluted Tubule (PCT)

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13
Q

Site of secretion

A

Distal Convoluted Tubule (DCT)

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14
Q
  • collect the urine that drains from each nephron
  • final site for either concentrating or diluting urine
A

Collecting Duct

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15
Q

A measure of the clearance of normal molecules that are not bound to protein and are freely filtered by the glomeruli neither reabsorbed nor secreted by the tubules

A

Glomerular filtration rate

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16
Q

GFR decreases by ____ mL/min/year after age 20-30 years

A

1.0 mL/min/yea

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17
Q

How much glomerular filtrate is produced daily?

A

150 L (according to the book of Dean rodriguez CC)

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18
Q

Removal of substance from plasma into urine over a fixed time

A

Clearances

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19
Q

Plasma concentration and clearance is _____ proportional

A

Inversely

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20
Q

Formula for Clearance

A

= U/P x Volume/minutes x 1.73/A

U = conc. of urine
P = Conc. of plasma
V = Volume of urine for 24 hours
Minutes = Time required to collect urine (1440 mins)
1.73 = Ave. body surface
A = Body surface area of the patient

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21
Q

Preservative for Urinary hormones

A

Hydrochloric acid

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22
Q

Preservative for 24 hr urine sample

A

refrigeration/cooler

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23
Q
  • most commonly used; you don’t need additional preparation for the patient (no injections or fasting); collection should be a 24-hr. urine sample
  • Production and excretion is related directly to muscle mass
A

Clearance test

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24
Q

How many creatinine is excreted per day?

A

1.2-1.5 g

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25
Q

Continuous infusion for inulin clearance

A

500 mL of 1.5% inulin soln.

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26
Q

Priming dose for Inulin clearance

A

25 mL of 10% inulin solution

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27
Q

Gold standard/reference method of clearance
Has a higher values in male due to larger renal mass

A

Inulin clearance

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28
Q

Reference values of inulin clearance?

A

127 mL/min - Male
118 mL/min - Female

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29
Q

Why creatinine clearance is excellent for measurement of renal function?

A

Creatinine is freely filtered by the glomeruli but not reabsorbed

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30
Q

Production and excretion is related directly to muscle mass

A

Creatinine clearance

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31
Q

Causes of increased creatinine clearance

A

1) High cardiac output
2) Pregnancy
3) Burns
4) Carbon monoxide poisoning
CHUBPI

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32
Q

Causes of decreased creatinine clearance

A

1) Impaired kidney function
2) Shock, dehydration
3) Hemorrhage
4) Congestive heart failure
CHIS

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33
Q

Reference values of creatinine clearance?

A

85-125 mL/min - Male
75-112 mL/min - female

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34
Q

Cockcroft-gault formula

A

CrCl(mL/min) 140-age x lean body weight(kg)/Serum creatinine (mg/dL) x 72 (x 0.85 if female)

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35
Q

Why the renal clearance of Cystatin C cannot be measured?

A

Because it is completely reabsorbed

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36
Q
  • low-molecular-weight protein produced at a constant rate by most body tissues
  • rise more quickly than creatinine levels in acute kidney injury (AKI).
  • reabsorbed by the PCT
  • Increases more rapidly than creatinine in the early stages of GFR impairement
  • Not affected by muscle mass, age, diet and gender
A

Cystatin C

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37
Q

Reference values of Cystatin C

A

0.5-1 (adults)
0.9-3.4 (>65 yrs old)

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38
Q

byproduct of protein metabolism

A

Non-Protein Nitrogenous Compounds (NPN)

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39
Q
  • Major end product of protein and amino acid catabolism
  • Non-protein nitrogenous compound; 45% total NPN
  • 1st metabolite to elevate in kidney diseases
  • Better indicator of nitrogen intake and the state of hydration
A

Blood Urea Nitrogen (BUN)

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40
Q

Conversion factor of BUN to creatinine:

A

2.40

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41
Q

BUN to Creatinine normal ratio =

A

10:1-20:1

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42
Q

reference values of BUN

A

8-23 mg/dL (2.9-8.2 mmol/L)

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43
Q

end product of Diacetyl Monoxime Method

A

Yellow

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44
Q

Urease Method derived from

A

jack beans

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45
Q

Sodium Fluoride inhibits Urease.(True/False)

A

true

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46
Q

UV enzymatic method

A

Coupled Urease/ Glutamate Dehydrogenase Method:

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47
Q
  • Reference method for BUN/Urea
  • Definive method for creatinine
A

Isotope Dilution Mass Spectrometry (IDSM)

48
Q
  • Mother compound
  • product of kreb cycle
  • First analyte to be elevated in kidney disease
A

Urea

49
Q

Causes of decreased BUN

A

1) Poor nutrition
2) Hepatic disease
3) Impaired absorption (celiac disease)
4) Pregnancy

50
Q

Causes of increased BUN

A

1) Chronic renal disease
2) Stress
3) Burns
4) High protein diet
5) Dehydration

51
Q
  • Product of muscle breakdown
  • most common analyte to be used in monitoring kidney disease
A

Creatinine

52
Q

Creatinine is produced by 3 amino acids such as:

A

1) Methionine
2) Arginine
3) Lysine

53
Q

Reference value for Creatinine

A

0.5-1.5 mg/dL (44-133 umol/L)

54
Q

Common method used for creatinine

A

Jaffe method

55
Q

2 reagents used in Jaffe method

A

Jaffe A: saturated picric acid (yellow)
Jaffe B: 10% sodium hydroxide

56
Q

Jaffe A + Jaffe B=

A

Alkaline picrate solution

57
Q

End color of Jaffe method

A

red-orange complex (red tautomer)

58
Q
  • Sensitive and specific method
  • Time consuming and not readily automated
  • not routinely performed
A

Modified Jaffe method

59
Q

Reagents used in modified jaffe method to remove interferences

A
  • Lloyd’s reagent: Sodium aluminum silicate
  • Fuller’s earth: Aluminum magnesium silicate
60
Q
  • Has potential to replace Jaffe method (specific than Jaffe method)
  • Without interference from acetoacetate or cephalosporins
  • Creatininase is also known as creatinine aminohydrolase
A

Creatininase Hydrogen Peroxide (H2O2) method

61
Q
  • Enzymatic method that requires large of pre-incubation
  • not widely
A

Creatinine Aminohydrolase - CK method

62
Q

Used to eliminate nonspecificity of the Jaffe rxn; Specific than Jaffe test

A

Enzymatic method

63
Q
  • Method that is popular, inexpensive, rapid and easy to perform
  • It requires automated equipment for precision
  • Allows a rate-dependent separation of creatinine from interfering substances
A

Kinetic jaffe method

64
Q

Interferences in Kinetic Jaffe method

A

alpha-Keto acids and cephalosporins

65
Q

Causes of increased creatinine

A

1) Impaired renal function
2) Chronic nephritis
3) Muscular diseases - Myasthenia gravis, Muscular dystrohpy
4) Congestive heart failure

66
Q

Causes of decreased creatinine

A

1) Decreased muscle mass
2) Advanced and severe liver disease
3) Pregnancy
4) Inadequate dietary protein

67
Q
  • clinical term of azotemia
  • elevated BUN and Creatinine with signs and symptoms
  • Kidneys fail to eliminate waste products of metabolism
  • Characterized by anemia (normocytic, normochromic), Uremic frost (Dirty skin), generalized edema, foul breath and sweat is urine-like.
  • Symptoms: itch, restlessness syndrome (kumukuyakoy), anxiety, insomnia
A

Uremia

68
Q
  • Increased levels of BUN and Creatinine
A

Azotemia

69
Q
  • problem lies before kidney
  • marked decrease in renal blood flow
  • most common cause = hypoperfusion
A

Pre-Renal

70
Q

Why renal blood flow in pre renal azotemia decreases?

A

GFR decreases and Tubular reabsorption increases leading to slower filtrate flow

71
Q

Causes of Pre-renal azotemia

A
  • Dehydration
  • Shock
  • Congestive heart failure
  • Hypoperfusion
72
Q

The result of BUN and Creatinine of an individual who has hypoperfusion

A

BUN = increased
Crea = normal

73
Q

Pre-renal azotemia BUN to crea ratio =

A

> 20:1

74
Q
  • problem lies within the kidney
  • damage to structures within the kidney
A

Renal Azotemia

75
Q

What is the level of BUN and Crea in Renal Azotemia

A

both BUN and Crea levels are elevated
BUN = >100 mg/dL
Creatinine = >20 mg/dL
Uric acid = >12 mg/dL

76
Q

Renal azotemia BUN to crea ratio =

A

10-20:1

77
Q

Causes of renal azotemia

A
  • Acute/chronic renal disease
  • glomerulonephritis
  • Tissue damage
  • Decreased GFR
  • Striking BUN level but slowly rising creatinine value
78
Q
  • problem lies after the kidney
  • obstruction of urine outflow from the kidney
  • Urea level is higher than creatinine
A

Post-renal azotemia

79
Q

Why the level of urea is higher than creatinine in Post renal azotemia?

A
  • due to back-diffusion of urea into circulation
  • increased urea and creatinine in blood
80
Q

causes of post renal azotemia

A
  • renal calculi (nephrolithiasis)
  • cancer or tumors of genitourinary tract
  • Prostate enlargement
  • Obstruction
81
Q

Post renal azotemia BUN to Crea ratio =

A

<10:1

82
Q

most common cause of kidney failure In the Philippines

A
  • diabetes
  • hypertension
83
Q

Most common cause of UTI

A
  • Escherichia coli (females)
  • S. saprophyticus (sexually active females)
  • Sexually transmitted (males)
84
Q

Causes of low ratio (BUN:Crea) <10:1

A

1) Low protein diet
2) Acute tubular necrosis
3) Repeated dialysis
4) Hepatic disease

85
Q

Causes of high ratio (BUN:Crea) >20:1 with normal creatinine

A

1) Prerenal azotemia
2) Dehydration
3) Catabolic states
4) GI hemorrhage
5) High protein diet

86
Q

Causes of high ratio (BUN:Crea) >20:1 with increased creatinine

A

1) Postrenal azotemia
2) Pre renal azotemia with renal disease
3) Renal failure

87
Q
  • product of purine metabolism (purine and pyrimidine which are the two categories of the bases of DNA)
  • Final breakdown of nucleic acids catabolism in humans
  • Filtered, partially reabsorbed and secreted in the renal tubules
A

Blood Uric acid

88
Q

BUA is formed from _____ by the action of ____ in the liver and intestine

A

Xanthine, Xanthine oxidase

89
Q

BUA is derived from 3 sources:

A

1) Catabolism of ingested nucleoproteins
2) Catabolism of endogenous nucleoproteins
3) Transformation of endogenous purine nucleotides

90
Q

Reference values of BUA

A

Uricase
- 3.5-7.2 mgdL (0.21-0.43 mmol/L) - male
- 2.6-6.0 mg/dL (0.16-0.36 mmol/L) - female

91
Q

Foods that increase or with high uric acid

A
  • beans (mungo bean)
  • Balunbalunan/gizzard
92
Q

The principle of chemical method used in BUA

A

Reduction-oxidation rxn

93
Q

Reagent used in chemical method in BUA

A

a) Caraway
- most commonly used
- It uses Sodium carbonate (NaO3)

b) Folin
- Uses Sodium Cyanide which is toxic

94
Q

The incubation period after the addition of an alkali (NaCN/Na2CO3) to inactivate non-uric acid reactants

A

Lag phase

95
Q

Enzymatic method used in BUA

A

Uricase method

96
Q
  • Simpliest and the most specific method used for uric
    acid
  • Simplest and most specific method
  • Candidate reference method
A

Uricase method

97
Q

UV absorbance peak of uric acid

A

293 nm

98
Q

Principle of Uricase method

A
  • The enzyme uricase oxidizes uric acid to form allantoin.
  • Uric acid has a maximum peak of absorption of 293 nm.
  • The resultant product (allantoin) has no absorption at this wavelength
  • The decrease in the absorbance is proportional to the conc. of uric acid present in the sample
99
Q
  • Total number solute particles present/kg of solvent (moles/kg solvent)
  • Affected only by number of solutes present
A

Osmolality

100
Q

Colligative properties of Osmolality

A

1) Freezing point (incr. osm. = decr. FP)
2) Vapor pressure (incr. osm. = decr. VP)
FVD
3) Osmotic pressure (incr. osm. = incr. OP)
4) Boiling point (incr. osm. = incr. BP)
BOI

101
Q

Biomarkers od Kidney injury

A
  • Kidney injury molecule-1 (KIM-1)
  • Neutrophil gelatinase associated lipocalin (NGAL)
  • Insulin-like GF binding protein 7 (IGFB7)
  • Tissue inhibitor metalloroteinase-2 (TIMP-2)
102
Q

expressed in proximal tubular cells injured by ischemia or nephrotoxins

A

Kidney injury molecule-1 (KIM-1)

103
Q
  • a.k.a. lipocalin-2 or siderocalin
  • inflammation of kidney parenchyma and in kidney injury
A

Neutrophil gelatinase associated lipocalin (NGAL)

104
Q
  • deficiency of Hypoxanthine-guanine phosphoribosyltransferase (HGPRT)
  • increased uric acid
  • common in children (orange sand in diapers)
A

Lesch-Nyhan Syndrome

105
Q

An important enzyme in the biosynthesis of purines.
- Lack of this enzyme prevents the reutilization of purine bases in the nucleotide salvage pathway
- results in increased de novo synthesis of purine nucleotides and high plasma and urine concentrations of uric acid

A

Hypoxanthine-guanine phosphoribosyltransferase (HGPRT)

106
Q

Tests measuring tubular function

A

A) Excretion tests
B) Concentration test

107
Q

What are the Excretion Tests?

A
  • Para amino hippuric (PAH) acid test
  • Phenolsulfonphthalein test
108
Q
  • Measures renal plasma flow
  • Reference method for tubular function
A

Para-amino hippurate test

109
Q

Ref. range of Para-amino hippurate test

A

600-700 mL.minute

110
Q
  • Measures excretion of dye proportional to renal tubular mass
  • 6 mg of PSP is administered IV
A

Phenolsulfonphthalein dye test

111
Q

Ref. range of Phenolsulfonphthalein dye test

A

1200 mL/minute

112
Q
  • Collecting tubules and loops of Henle
  • It detect renal damage that is not yet severe enough to cause elevated plasma urea and creatinine
  • Used to assess the quantity of solutes present in urine, which reflects the ability of the kidney to produce a conc. urine
  • Monitors the conc. of Cl and Na in urine reveals the ability of the kidney to concentrate the ultrafiltrate in tubules
A

Concentration test

113
Q

Specimen used for conc. test

A

First morning urine

114
Q

3 most prevalent solutes excreted in concentration test

A
  • Urea
  • Cl
  • Na
115
Q

dependent on the number and size of particles

A

Specific Gravity

116
Q

dependent on the number of particles; freezing point

A

Osmolality