Non-Protein Nitrogen Compounds Flashcards
(121 cards)
1
Q
Product of analytic methodology
requiring removal of protein from sample before analysis
A
Nonportein nitrogen compounds
2
Q
NPN compounds are used to
A
Monitor renal or kidney function
3
Q
Concentration of nitrogen-containing compounds was quantified spectrophotometrically by converting nitrogen to
A
Ammonia
4
Q
Majority of NPN compounds arise from catabolism of
A
Proteins
Nucleic acids
5
Q
Approximate plasma concentration (% of total NPN)
A
Urea 45-50
Amino Acids 25
Uric Acid 10
Creatinine 5
Creatine 1-2
Ammonia 0.2
6
Q
Approximate urine concentration (% of excreted)
A
Urea 86.0
Amino Acids -
Uric Acid 1.7
Creatinine 4.5
Creatine -
Ammonia 2.8
7
Q
NPN with the highest concentration in the blood
A
Urea
8
Q
Major excretory product of protein metabolism
A
Urea
9
Q
Organ that synthesize urea
A
Liver
10
Q
Two forms of urea
A
Blood urea nitrogen (BUN)
Urea nitrogen (UN)
11
Q
Urea N → Urea concentration
A
Urea N x 2.14
12
Q
Clinical function of urea
A
Evaluate renal function
Assess hydration status
To determine nitrogen balance
To aid in the diagnosis of renal disease
To verify adequacy of dialysis
13
Q
Factors that affect concentration of urea in the plasma
A
Protein content of the diet
Rate of protein catabolism
Renal function
Perfusion
14
Q
Urea is reported in terms of
A
Nitrogen concentration
15
Q
Chemical Method (Direct Method) for Urea
A
Diacetyl monoxime method
16
Q
Substrate of Diacetyl monoxime method
A
Urea + DAM
17
Q
Product of Diacetyl monoxime method
A
Yellow Diazine Derivative
18
Q
Enzymatic Methods (Indirect Method) for Urea
A
Urease (Urea aminohydrolase)
Coupled Urease/ Glutamate Dehydrogenase method
19
Q
Proposed reference method for urea
A
Isotope dilution mass spectrometry (IDMS)
20
Q
Conversion factor of Urea
A
0.357
21
Q
Specimens for urea measurements
A
Plasma
Serum
Urine
22
Q
Fasting sample is required for urea measurements. True or False?
A
False; not required
23
Q
Why cant we use citrate and fluoride in plasma when measuring urea?
A
Citrate and fluoride inhibit urease
24
Q
Why should we refrigerate urine samples for urea e=measurements?
A
Urea is susceptible to bacterial decomposition
25
Alevated urea in the blood
Azotemia
26
3 main categories of azotemia
Prerenal
Renal
Postrenal
27
Azotemia as a result of reduced renal blood flow
Prerenal azotemia
28
Pathophysiology of prerenal azotemia
Less blood is delivered to the kidney, therefore less urea is being filtered or excreted. Thus, results to increase blood urea nitrogen concentration
29
Azotemia as a result of diminished glomerular filtration which occurs in wide variety of kidney diseases
Renal azotemia
30
Culprit of renal azotemia
Kidney damage or abnormal kidney
function
31
Azotemia as a result of obstruction of the urine flow and anywhere in the urinary tract by renal calculi, tumors of the bladder or prostate or severe infection
Postrenal azotemia
32
Elevated urea in the blood accompanied by renal failure
Uremia
33
Cause of decreased plasma urea
Low protein intake
Severe liver disease
34
Urea is produced from protein metabolism. True or False?
True
35
BUN or Urea N/Creatinine ratio
10:1-20:1
36
High (>20:1) BUN or Urea N/Creatinine ratio indicates
Prerenal and Postrenal azotemia
37
Low (<20:1) BUN or Urea N/Creatinine ratio indicates
Decreased urea production
38
Reference interval of plasma/serum urea nitrogen
6-20 mg/dL
39
Reference interval 24hr urine urea nitrogen
12-20 g/d
40
The product of catabolism of the purine nucleic acids (adenine and guanine)
Uric acid
41
98-100% of uric acid is reabsorbed in the proximal tubules. True or False?
True
42
Uric acid is soluble in plasma. True or False?
False; not soluble
43
Deposition of uric acid in joints
Gout
44
Deposition of uric acid in tissue
Tophi
45
Organs that convert purines into uric acid
Liver
46
Nearly all of the uric acid in plasma is present as
Monosodium urates
47
Clinical use of uric acid
To confirm diagnosis and monitor
treatment of gout
To prevent uric acid nephropathy
during chemotherapeutic treatment
To assess inherited disorders of purine metabolism
To detect kidney dysfunction
To assist in the diagnosis of renal calculi
48
Chemical method for uric acid measurements
Caraway method
49
Principle of Caraway method
Reduction of the phosphotungstic acid to produce tungsten blue
50
Enzymatic methods for uric acid measurements
Uricase (urate oxidase)
Peroxidase
51
More specific method for uric acid measurements
Uricase method
52
Substrate and product of Uricase (urate oxidase) method
Uric acid → allantoin
53
Substrates of Peroxidase method for uric acid measurements
Hydrogen peroxide + indicator dye
54
Product of Peroxidase method for uric acid measurements
Colored compound
55
Proposed reference method for uric acid
Isotope dilution mass spectrometry (IDMS)
56
Specimens for uric acid measurements
Heparinized plasma, serum, or urine
57
Anticoagulant of choice for uric acid measurements
Heparin
58
Urine pH for uric acid measurements
Alkaline (8.0)
58
Increased plasma uric acid concentration
Hyperuricemia
58
Inherited disorders of purine metabolism
Lesch-Nyhan syndrome
Phosphoribosylpyrophosphate
synthetase deficiency
59
Cause of Lesch-Nyhan syndrome
Hypoxanthine-guanine
phosphoribosyltransferase deficiency
60
Cause of Fructose Intolerance
Fructose-1-phosphate aldolase deficiency
61
Inflammation in joints caused by the deposition of uric acid specifically sodium urate
Gout
62
Deposition of uric acid in tissues, causing deformities
Tophi
63
Ethanol decreases uric acid concentration. True or False?
False; increases
64
Decreased plasma uric acid concentration
Hypouricemia
65
Causes of decreased uric acid
Sever liver disease
Defective tubular reabsorption
Chemotherapy with 6-mercaptopurine or azathioprine
Overtreatment with allopurinol
66
98%-100% of uric acid is reabsorbed in the distal convoluted tubules. True or False?
False; PCT
67
Conversion factor of uric acid
0.0595
68
Reference interval of plasma/serum uric acid in males
3.5-7.2 mg/dL
69
Reference interval of plasma/serum uric acid in females
2.6-6.0 mg/dL
70
Reference interval of plasma/serum uric acid in children
2.0-5.5 mg/dL
71
Reference interval of 24 hour uric acid in adults
250-270 mg/d
72
Formed from creatine and creatine phosphate in muscle and is excreted into the plasma at a constant rate related to muscle mass
Creatinine
73
Correlation between creatine concentration and muscle mass
Directly proportional
74
Correlation between plasma creatine and glomerular filtration rate (GFR)
Inversely related
75
Creatine is synthesized primarily in the _____ from _____, _____, and _____
Liver
Arginine, glycine, and methionine
76
Creatine will be transported to the muscles to be converted into
Creatine phosphate
77
Clinical use of creatinine measurement
To determine the sufficiency of kidney function
To determine the severity of kidney damage
To monitor the progression of kidney disease
78
A measure of the amount of creatinine eliminated from the blood by the kidneys, and GFR are used to gauge renal function
Creatinine clearance (CrCl)
79
Variables included in Modification of Diet in Renal Disease (MDRD) equation
Serum creatinine concentration
Age
Gender (sex)
Ethnicity
80
The standard body surface area in GFR calculation
1.73 m^2
81
Chemical methods based on Jaffe reaction
Jaffe Reaction
Kinetic Jaffe (modified Jaffe method)
Jaffe with adsorbent
82
Substrates of Jaffe Reaction
Creatinine + alkaline picrate
83
Product of Jaffe Reaction
Red-orange chromogen/reddish chromogen
84
Composition of Jaffe reagent (alkaline picrate)
Saturated picric acid and 10% NaOH
85
Interferences in Kinetic Jaffe
α-ketoacids and cephalosporins
86
Effect α-ketoacids and cephalosporins in kinetic Jaffe method
False increased levels
87
Adsorbent used in Jaffe
Fuller’s earth (aluminum magnesium silicate)
Lloyd’s reagent (sodium aluminum silicate)
88
Enzymatic methods for creatinine measurements
Creatinine Aminohydrolase-CK method
Creatininase-Hydrogen Peroxide Method
89
Specimen for creatinine/creatine measurements
Plasma, serum, urine (refrigerated after collection or frozen if stored longer than 4 days but if it is a timed urine sample then refrigerate during collection period)
90
Drugs that increase creatinine concentration
Cephalosporin
Dopamine
Lidocaine
91
Enzymatic method for creatine
Creatine aminohydrolase-CK method
92
Chromatography for creatinine/creatine
High Performance Liquid Chromatography (HPLC)
93
Increased plasma creatinine indicates
Abnormal renal function
94
Increased plasma creatine indicates
Muscle disease
95
Correlation between creatine and glomerular filtration rate
Inversely related
96
Pathophysiology of muscle disease due to increased plasma creatine
Creatine after being produced by the liver is stored in muscles but in muscle diseases creatine escapes and goes to the circulation
97
Conversion factor of creatinine
88.4
98
Reference interval of plasma/serum creatinine in males
Jaffe method: 0.9-1.3 mg/dL
Enzymatic method: 0.6-1.1 mg/dL
99
Reference interval of plasma/serum creatinine in females
Jaffe method: 0.6- 1.1 mg/dL
Enzymatic method: 0.5-0.8 mg/dL
100
Reference interval of plasma/serum creatinine in children
Jaffe method: 0.3-0.7 mg/dL
Enzymatic method: 0.0-0.6 mg/dL
101
Reference interval of 24 hour urine creatinine in males
Jaffe method: 800-2000 mg/d
102
Reference interval of 24 hour urine creatinine in females
Jaffe method: 600-1800 mg/d
103
Produced in the deamination of amino acids during protein metabolism and by bacterial metabolism in the lumen of the intestine
Ammonia
104
How does the body get rid of ammonia?
Converted to urea in the liver
105
Free ammonia is nontoxic. True or False?
False; toxic
106
Most ammonia in the blood exists as
Ammonium ion
107
Enzymatic method for ammonia measurements
Glutamate dehydrogenase method
108
Most commonly used method to determine ammonia
Glutamate dehydrogenase method
109
Direct measurement of ammonia
Ion Selective Electrode (ISE) - Change in pH
110
Product of Dry Slide System: Thin Film Colorimetric Assay
Colored compound
111
Suitable anticoagulants for ammonia measurements
Heparin
EDTA
112
Samples for ammonia measurements should be centrifuged at _____ within _____ of collection and the plasma or serum should be removed _____
0 to 4°C
20 minutes
Immediately
113
Frozen plasma is stable for several days at –20°C. True or False?
True
114
Source of ammonia
contamination
Cigarette smoking
115
Increased plasma ammonia concentration
Hyperammonemia
116
Conditions due to hyperammonemia
Severe liver disease
Reye's syndrome
Inherited deficiency of enzymes of the urea cycle
117
Reference interval of plasma ammonia in adult
10-60ug/dL
118
Reference interval of 24 urine ammonia in adult
140-1500 mg N/d
119
Reference interval of plasma ammonia in children (10d-2y)
68-136 ug/dL
