Kidney Function Tests Flashcards
1
Q
Tests for GFR
Clearance:
A
-Inulin clearance
-Creatinine clearance
-Urea clearance
2
Q
Phenolsulfonphthalein dye test
A
GFR
3
Q
Cystatin C
A
GFR
4
Q
Tests for Renal Blood Flow
A
BUN
Creatinine
Uric acid
5
Q
Tests Measuring Tubular Function
Excretion:
Concentration:
A
-Para-amino hippurate test (Diodrast test)
-Phenolsulfonphthalein dye test
-Specific gravity
-Osmolality
6
Q
Decreases by 1.0 mL/min/year after age 20-30 years
A
GFR
7
Q
of glomerular filtrate is produced daily
A
150 L
8
Q
Reference method for GFR
A
Inulin clearance
9
Q
Best alternative method
A
Creatinine clearance
10
Q
Measure of the completeness of a 24-hour urine collection
A
Creatinine clearance
11
Q
Creatinine clearance Excretion:
A
1.2-1.5 g creatinine/day
12
Q
Demonstrate progression of renal disease or response to therapy
A
Urea clearance
13
Q
Low MW protease inhibitor
A
Cystatin C
14
Q
Filtered > Not secreted > Completely reabsorbed (PCT)
A
Cystatin C
15
Q
Indirect estimates of GFR
A
Cystatin C
16
Q
Its presence in urine denotes damage to PCT
A
Cystatin C
17
Q
Synthesized from Ornithine or Kreb’s Henseleit cycle
A
BUN
18
Q
First metabolite to elevate in kidney diseases
A
BUN
19
Q
Better indicator of nitrogen intake and state of hydration
A
BUN
20
Q
BUN > Urea (mg/dL)
A
2.14
21
Q
Inhibit urease
A
Fluoride or citrate
22
Q
Enhance color development (BUN mtd)
A
Thiosemicarbazide
Ferric ions
23
Q
Yellow diazine derivative
A
Diacetyl monoxime method
24
Q
BUN: Routinely used
A
Urease method
25
: prepared from jack beans
Urease
26
Urea ---(Urease)-->
NH4 + Berthelot reagent (Measure ammonia)
27
Coupled urease
Glutamate dehydrogenase method
28
UV enzymatic method
Coupled urease
29
BUN: Reference method
Isotope dilution mass spectrometry
30
For research purposes
Isotope dilution mass spectrometry
31
NPN
45% Urea
20% Amino acid
20% Uric acid
5% Creatinine
1-2% Creatine
0.2% Ammonia
32
Creatinine: Derived from
alpha-methyl guanidoacetic acid
33
Produced by 3 amino acids (methionine, arginine, lysine)
Creatinine
34
Most commonly used to monitor renal function
Creatinine
35
Enzymatic methods (Creatinine)
Creatinine Aminohydrolase – CK method
Creatinase-Hydrogen Peroxide method – benzoquinonemine dye (red)
Creatininase (a.k.a. creatinine aminohydrolase)
36
Formation of red tautomer of creatinine picrate
Direct Jaffe method
37
Interferences (Direct Jaffe) Falsely increased:
Ascorbate
Glucose
Uric acid
Alpha-keto acids
38
(+) Red orange tautomer
Folin Wu Method
39
True measure of creatinine
Lloyd’s or Fuller’s Earth method
40
Sensitive and specific
Lloyd’s or Fuller’s Earth method
41
Uses adsorbent to remove interferences (UA, Hgb, Bili)
Lloyd’s or Fuller’s Earth method
42
Lloyd’s reagent
Sodium aluminum silicate
43
Fuller’s earth reagent
Aluminum magnesium silicate
44
Jaffe reagent (Alk. picrate)
Satd. picric acid + 10% NaOH
45
Popular, inexpensive, rapid and easy to perform
Kinetic Jaffe method
46
Requires automated equipment
Kinetic Jaffe method
47
Elevated urea and creatinine in blood
Azotemia
48
Decreased GFR but normal renal function
Pre-renal azotemia
49
Dehydration, shock, CHF
Pre-renal azotemia
50
Increased: BUN
Normal: Creatinine
Pre-renal azotemia
51
True renal disease
Renal azotemia
52
GFR Striking BUN level but slowly rising creatinine value
Renal azotemia
53
BUN = >100 mg/dL
Creatinine = >20 mg/dL
Uric acid = >12 mg/dL
Renal azotemia
54
Urinary tract obstruction
Post renal azotemia
55
Decreased GFR
Pre and Post renal azotemia
56
Nephrolithiasis, cancer or tumors of GUT
Post renal azotemia
57
Creatinine = normal or slightly increased
Post renal azotemia
58
Marked elevation of urea, accompanied by acidemia and electrolyte imbalance
Uremia
59
(K+ elevation) of renal failure
Uremia
60
Normocytic, normochromic anemia
Uremia
61
Uremic frost (dirty skin)
Uremia
62
Edema
Uremia
63
Foul breath
Uremia
64
Urine-like sweat
Uremia
65
From purine (adenine and guanine) catabolism
Uric acid
66
Uric acid Excretion:
1g/day
67
-Gout
Hyperuricemia
68
-Increased nuclear metabolism
Hyperuricemia
69
-Chronic renal disease
Hyperuricemia
70
-Lesch-Nyhan syndrome (HGPRT deficiency)
Hyperuricemia
71
Fanconi’s syndrome
Hypouricemia
72
Wilson’s disease
Hypouricemia
73
Hodgkin’s disease
Hypouricemia
74
Stable for 3 days
Methods (Uric acid)
75
Potassium oxalate cannot be used
Methods (Uric acid)
76
Methods (Uric acid) Major interferences:
Ascorbate and bilirubin
77
Phosphotungstic acid mtd:
Uric acid + Phosphotungstic acid ---(NaCN/NaCO3)--> Tungsten blue + Allantoin
78
NaCN
Folin
Newton
Brown
Benedict
79
NaCO3
Archibald
Henry
Caraway
80
Incubation period after the addition of an alkali to inactivate non-uric acid reactants
Lagphase
81
UREA: Simplest and most specific method
Uricase method
82
URIC ACID: Candidate reference method
Uricase method
83
Uricase method
Uric acid (Absorbance at 293nm) ---[Uricase]--> Allantoin (No absorbance)
84
Decrease in absorbance α uric acid concentration
Uricase method
85
Measures renal plasma flow
Para-amino hippurate test
86
Reference method for tubular function
Para-amino hippurate test
87
Measures excretion of dye proportional to renal tubular mass
Phenolsulfonphthalein dye test
88
6 mg of PSP is administered IV
Phenolsulfonphthalein dye test
89
Collecting tubules and loops of Henle
Concentration tests
90
Concentration tests Specimen:
1st morning urine
91
Specific gravity
Affected by [?]
SG > [?]: X-ray dye and mannitol
[?]= SG of ultrafiltrate in Bowman’s space
solute number and mass
1.050
1.010
92
Total number solute particles present/kg of solvent (moles/kg solvent)
Osmolality
93
Affectted only by number of solutes present
Osmolality
94
Urine osmolality = due to
Serum osmolality = due to
urea
sodium and chloride
95
Det. by Colligative properties:
Freezing point
Vapor pressure
Osmotic pressure
Boiling point
Freezing point (incr. osm. = decr. FP)
Vapor pressure (incr. osm. = decr. VP)
Osmotic pressure (incr. osm. = incr. OP)
Boiling point (incr. osm. = incr. BP)
96
Direct methods (Osmolality)
= popular method
(Seebeck effect)
Freezing point osmometry
Vapor pressure osmometry
97
Incr. vasopressin (H2O reabsorption) =
decr. plasma osmolality
98
Tubular failure
Increased:
Decreased:
BUN, creatinine, calcium
Phosphate
99
Difference between measured and calculated osmolality
Osmolal gap
100
Sensitive indicator of alcohol or drug overdose
Osmolal gap
101
Sensitive indicator of alcohol or drug overdose
Osmolal gap
102
Osmolal gap: >12 mOsm/kg
DKA
Drug overdose
Renal failure
103
Creatinine Clearance:
Male =
Female =
85-125 mL/min
75-112 mL/min
104
BUN =
8-23 mg/dL
105
BUN =
8-23 mg/dL
106
Uric acid:
Male =
Female =
3.5-7.2 mg/dL
2.6-6.0 mg/dL
107
Renal plasma flow (PAH) =
600-700 mL/min
108
Renal blood flow (PSP) =
1200 mL/min
109
SG =
1.005-1.030
110
Osmolality:
Serum =
Urine (24-hr) =
275-295 mOsm/kg
300-900 mOsm/kg [<290 mOsm/kg = kidney damage]
111
Urine osmolality: Serum osmolality =
1:1 to 3:1
112
[= Glomerular disease]
>1:1
113
[= loss of renal concentrating ability]
1.2:1
114
[= Diabetes Insipidus]
<1:1
115
-Increased nuclear metabolism Tx:
Allopurinol
