Unit 4.1 - NPN (Urea) Flashcards
1
Q
Nitrogen containing substances found in blood that are not proteins.
A
Nonprotein Nitrogen Compounds
2
Q
For assessment and monitoring of renal function.
Ex: Urea, BUN, Creatinine, Ammonia, Uric Acid
A
Nonprotein Nitrogen Compounds
3
Q
Before the current analytical methods available, this method is used to remove the proteins before analysis in measuring the nitrogen content.
A
Protein Free Filtrate (PFF)
4
Q
What are the clinically significant Nonprotein Nitrogen Compounds?
A
- Urea
- Amino acids
- Uric acids
- Creatinine
- Creatine
- Ammonia
5
Q
What is the approximate plasma concentration of Urea?
A
45-50%
6
Q
What is the approximate plasma concentration of Uric acid?
A
10%
7
Q
What is the approximate plasma concentration of Creatinine?
A
5%
8
Q
What is the approximate plasma concentration of Creatine?
A
1-2%
9
Q
What is the approximate plasma concentration of Ammonia?
A
0.2%
10
Q
What is the approximate urine concentration of Urea?
A
86.0%
11
Q
What is the approximate urine concentration of Uric acid?
A
1.7%
12
Q
What is the approximate urine concentration of Creatinine?
A
4.5%
13
Q
What is the approximate urine concentration of Creatine?
A
No!
char wala
14
Q
What is the approximate urine concentration of Ammonia?
A
2.8%
15
Q
This NPN is found in the blood, and the major excretory product from protein metabolism.
A
Urea
16
Q
Urea is synthesized in what organ during the protein catabolism?
A
Liver
17
Q
Renal or liver disease
Increase in ammonia, and decrease in urea would lead to?
A
Renal disease
18
Q
Renal or liver disease:
Decrease in ammonia = low protein in-take would lead to?
A
Liver disease
19
Q
This cycle takes places in hepatocytes and is a compartmentalized process between the mitochondria and cytosol.
A
Urea Cycle
20
Q
Other name of Urea Cycle:
A
Krebs Henseleit Cycle
21
Q
In mitochondria during urea cycle, what are the two molecules formed?
A
- Carbamoyl phosphate
- Citrulline
22
Q
What are the important enzymes in cytosol during urea cycle?
A
- Arginase enzyme
- Argininosuccinate synthetase
- Argininosuccinate lyase
23
Q
This enzyme located in the cytosol forms & release the urea.
A
Arginase enzyme
24
Q
NPN that is filtered freely by the glomerulus.
A
Urea
25
% of urea that is re-absorbed.
40-60%
26
% of excreted urine in the urea.
50%
27
% of urea excreted through GI tract & skin.
<10%
28
Concentration of urea is dependent on: (3)
1. Renal function
2. Protein content of diet
3. Amount of protein metabolism
29
Determination of urinary concentration is of value in the assessment of nitrogen balance for nutritional management.
Blood Urea Nitrogen
30
Molecular weight of Urea:
60 mg/mmol
31
Conversion of BUN to UREA:
BUN x 2.14
32
Conversion of UREA to BUN:
UREA X 0.467 or UREA/(1/2.14)
33
What are the clinical applications of Urea? (5)
* Evaluate renal function
* Determine hydration status
* Assess nitrogen balance
* Aid in the diagnosis of renal disease
* Verify adequacy of dialysis
34
# Urea pathophysiology:
An elevated concentration of urea in the blood.
Azotemia
35
# Urea pathophysiology:
Mainly due to **laboratory findings**, patient can have an asymptomatic condition.
Azotemia
36
# Urea pathophysiology:
Has very high levels of plasma urea accompanied by renal failure.
Uremia/Uremic Syndrome
37
# Urea pathophysiology:
A condition where the urine is deposited through the skin.
Uremic frost
38
# Urea pathophysiology:
3 phases of Azotemia
1. Pre-renal
2. Renal/Intrinsic
3. Post-renal
39
# Identify if pre, renal, post azotemia:
* Decreased blood flow to the kidney
* Decreased filtration = resulting to increased urea in the blood
* Increased reabsorbtion of water
Pre-renal Azotemia
40
# Identify if pre, renal, post azotemia:
Directly damages the kidney, cannot remove NPNs
Renal/Intrinsic Azotemia
41
# Identify if pre, renal, post azotemia:
* Increase NPNs, waste substances
* Obstruction in urinary tract
* Example: Kidney Stones
Post-renal azotemia
42
# Identify if pre, renal, post azotemia:
Impaired perfusion:
* Cardiac failure
* Sepsis
* Blood loss
* Dehydration
* Vascular occlusion
Pre-renal Azotemia
43
# Identify if pre, renal, post azotemia:
* Glomerulonephritis
* Small-vessel vasculitis
* Acute tubular necrosis
* Interstitial nephristis
Renal/Intrinsic Azotemia
44
# Identify if pre, renal, post azotemia:
* Urinary calculi
* Retroperitoneal fibrosis
* Benign prostatic enlargement
* Prostate cancer
* Cervical cancer
* Urethral stricture/valves
* Meatal stenosis/phimosis
Post-renal Azotemia
45
# Identify if pre, renal, post azotemia:
* Decreased blood flow to the kidney
* Congestive heart failure
* Shock, haemorrage
* Dehydration
Pre-renal Azotemia
46
What are the other causes of Pre-renal Azotemia?
* Level of protein metabolism
* High protein diet
* Increased fever catabolism
47
# Pre-renal azotemia:
Causes of increased protein catabolism (6):
1. Fever
2. Mental illness
3. Stress
4. Burns
5. Corticosteroid therapy
6. GI Bleeding
48
What are the 3 causes of Acute Renal Failure?
1. Prerenal
2. Intrarenal
3. Postrenal
49
# T/F:
The basis of identifying the causes/types of Azotemia is Urea.
FALSE!!!!!!
| Dapat blood :D
50
# Identify if pre-renal, renal, post-renal:
High urea: Normal creatinine
Pre-renal azotemia
51
# Identify if pre-renal, renal, post-renal:
High urea: High creatinine
Renal azotemia
52
# Identify if pre-renal, renal, post-renal:
Normal urea: High creatinine
Post-renal azotemia
53
Normal value of a normal BUN:
6-20 mg/dL
54
Urea Nitrogen: Creatinine Normal ratio?
10:1 - 20:1
55
Normal value of normal creatinine:
0.5-1 mg/dL
| But still varies to gender (as creatinine of male is higher than female)
56
The following conditions could be linked to renal azotemia except:
a. High urea, high creatinine
b. Glomerulonephritis
c. Direct damage to the kidneys due to reduced blood supply
d. High urea and normal creatinine
e. Uremic syndrome
f. "Normal" BUN/Creatinine ratio
d. High urea and normal creatinine
| Associated with pre-renal azotemia
57
What are the conditions with **decreased levels** of plasma urea? (6)
1. decreased protein intake
2. poor nutrition
3. high fluid intake, overhydration
4. sever liver disease
5. severe vomiting & diarrhea
6. increased protein synthesis
58
2 types of Urea Determination?
1. Direct method
2. Indirect method
59
# Direct/Indirect:
Measures urea as a whole:
Direct Method
60
# Direct/Indirect:
Measures the nitrogen contect of uea (BUN)
Indirect
61
# Urea determination (chemical method):
Also known as **Friedman's Method** or **Xanthydrol Method**
Condensation with Diacetyl Monoxime Method
62
# Urea determination (chemical method):
What are the reagents used in Condensation with Diacetyl Monoxime Method?
* strong acid
* oxidizing agent
* ferric ions
* thiosemicarbazide
63
# Urea determination (chemical method):
Product of Condensation with Diacetyl Monoxime Method:
yellow diazine derivative
64
# Urea determination (chemical method):
DAM + water ===(H+) diacetyl
Diacetyl + urea === (Fe3+) diazine
Condensation with Diacetyl Monoxime Method
65
# Urea determination (chemical method):
Disadvantages of Friedman's Method or Xanthydrol Method: (2)
1. non-specific
2. uses toxic substances
66
# Urea determination (chemical method):
Advantages of Friedman's Method or Xanthydrol Method: (2)
1. ammonia does not interfere
2. used in autoanalyzers
67
# Urea determination (chemical method):
Urea + o-pthalaldehdyde (H+) -> **isoindoline + naphthylethylene diamine (H+) -> colored product**
Reaction w/ o-pthalaldehdyde and naphthylethylene
68
# Urea determination (chemical method):
Product of Reaction w/ o-pthalaldehdyde and naphthylethylene?
chromogen or colored product
69
# Urea determination (chemical method):
Advantages of Reaction w/ o-pthalaldehdyde and naphthylethylene? (2)
1. no ammonia interference
2. used in automation
70
# Urea determination (chemical method):
Disadvantages of Reaction w/ o-pthalaldehdyde and naphthylethylene? (1)
1. sulfa containing drugs interfere
71
# Urea determination (chemical method):
NH4+ (alkalinized) → NH3 ↑ + K2HgI4 → NH2Hg2I3
Micro-Kjeldahl Nessler Method
72
# Urea determination (chemical method):
Digestion of Micro-Kjeldahl Nessler Method
Urea to Ammonium (NH4+)
73
# Urea determination (chemical method):
Product of Micro-Kjeldahl Nessler Method
yellow compound
74
# Urea determination (enzymatic method):
Urea (urease) → HCO3- + NH4+ + **Gum Ghatti (alkaline)** + **Nessler’s reagent** → NH2Hg2I3 (yellow)
Urease-Nessler's Method
75
# Urea determination (enzymatic method):
Optimal temperature of Urease-Nessler Method:
37 degree
76
# Urea determination (enzymatic method):
Urea (urease) → HCO3- + NH4+ + sodium nitroprusside (alkaline) + phenol hypochlorite → **indophenol blue** + NaCl + H2O
Urease-Berthelot's Method
77
# Urea determination (enzymatic method):
Disadvantages of Urease-Berthelot's Method: (2)
1. not specific
2. very sensitive to interference from endogenous ammonia
78
# Urea determination (enzymatic method):
* Best to perform in kinetic method
* Most common method in automation
Urease-L-Glutamate Dehydrogenase Method (GLDH Method)
79
# Urea determination (enzymatic method):
2 enzymes used in GLDH method:
1. Urease
2. GLDH
80
# Urea determination (enzymatic method):
Absorbance in measuring the GLDH method
340 nm
81
# Urea determination (enzymatic method):
Urea + 2H2O → 2NH4+ CO23-
Urease Conductimetric Method
82
# Urea determination (enzymatic method):
**Conductivity of ammonium** is measured.
Urease Conductimetric Method
83
# Analytical methods:
* Proposed reference method of urea
* Confirmatory purpose
* Debatable results
* Not used in routine
* Sensitive & specific
Isotope Dilution Mass Spectrometry (IDMS)
84
# Analytical methods:
Detecion of characteristic fragments following ionization; quantification using isotopically labaled compound
IDMS
85
Specimen requirements for measuring Urea:
**Non-hemolyzed** sample (plasma/serum) or urine
86
If plasma is used, any additive is used except _ & _ which interferes w/ urease and ammonium ions.
1. Light blue top (sodium citrate)
2. Gray top (sodium fluoride)
87
Urea is suspectible to bacterial composition, urine sample should be _
refrigerated
88
# T/F:
Protein content of diet influences urea but minimal: **has fasting requirement.**
False
89
# T/F:
A reference method for measuring Urea is Micro-Kjeldahl Nessler method.
False.
| Should be IDMS
90
# T/F:
Sodium citrate & fluoride are the recommended collection additive when measuring Urea concentration.
False
| not recommended.
91
# T/F:
Increased concentrations of Urea could be seen in low protein intake, liver disease, and severe vomiting and diarrhea.
False.
| decreased
91
# T/F:
Urea measurement will come out elevated in azotemia, uremic syncrome, and prerenal conditions.
True
92
**Reference interval** of urea nitrogen for adult in **plasma/serum**:
6-20 mg/dL or 2.1-7.1 mmol/L
93
**Reference interval** of urea nitrogen for adult in **24-hour urine**:
12-20 g/day or 0.43-0.71 mol urea/day
