NON-PROTEIN NITROGEN COMPOUNDS Flashcards
(127 cards)
1
Q
pair of grandular organs located at the retroperitoneal space
A
KIDNEYS
2
Q
slightly lower than the other; adjacent to the liver
A
right kidney
3
Q
FUNCTIONS OF THE KIDNEYS
A
- Excretory function
- Regulatory function
- Endocrine function
4
Q
eliminates wastes and excess inorganic substances via urine formation
A
Excretory function
5
Q
play a major role in homeostasis (balance)
A
Regulatory function
6
Q
mechanism of differential reabsorption and secretion in the renal tubule
A
Regulatory function
7
Q
Primary Endocrine function
:
A
production of hormones
8
Q
Secondary Endocrine function:
A
degradation of insulin, glucagon and aldosterone
9
Q
Urine formation
A
Glomerular filtration
Tubular reabsorption
Tubular secretion
10
Q
substances are excreted out in the urine
A
Tubular secretion
11
Q
substances are transferred from renal tubule to the circulation (ex. electrolytes: sodium - major extracellular cation)
A
Tubular reabsorption
12
Q
- major extracellular cation
A
sodium
13
Q
– absence of urine output; kidney failure
A
anuria
14
Q
urine production diminishes – accumulation of [?]
A
metabolic waste
15
Q
maintenance of which substances in the circulation
A
electrolytes
glucose
amino acids
water
16
Q
maintenance of substances and pH in the circulation
A
homeostasis
17
Q
the kidneys are capable of regulating these processes
A
mechanism of differential reabsorption and secretion in the renal tubule
18
Q
– tuft of capillaries
A
glomerulus
19
Q
– enclosing the glomerulus
A
bowman’s capsule
20
Q
other parts:
A
renal tubules, ascending/descending loop of Henlee, PCT, DCT
21
Q
– surrounding the tubules
A
peritubular capillaries
22
Q
– hormone that regulates blood pressure
A
Renin
23
Q
Renin-Angiotensin-Aldosterone System
A
Primary
24
Q
– milk-curdling enzyme produced by neonates
A
Rennin
25
similar to pepsin in adults
Rennin
26
– hormone-like behavior; responsible for pain and muscle contraction (ex. tooth-ache)
Prostaglandin
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– prevents production of prostaglandin, relieving pain
Analgesic
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- hormone that regulates the production of rbc
Erythropoietin
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– action of the hormone is targeted to a particular organ so that a specific process is stimulated and eventually degraded
Target organ
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Not protein but has nitrogen in their structure
31
Most of them are used to evaluate renal function
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Derived from the catabolism of proteins and nucleic acids
33
Clinically significant NPN cpds:
1. urea – 45%
2. amino acids – 20%
3. uric acid – 20%
4. creatinine – 5 %
5. creatine – 1-2 %
6. ammonia – 0.2%
34
important metabolytes; undergo reabsorption
2. amino acids
5. creatine
35
for protein production
amino acids
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for energy metabolism
creatine
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found in skeletal muscles
creatine
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Nitrogen in a protein-free filtrate (a specimen) is converted to NH3 (ammonia) using hot H2SO4 (sulfuric acid)
KJELDAHL DIGESTION
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Nessler’s reagent –
double iodide salt of potassium & mercury
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– yellow to orange brown product
Dimercuric ammonium iodide
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BERTHELOT METHOD
Reactant:
Reagent:
Catalyst:
Product:
NH3
phenol and alkaline hypochlorite
sodium nitroprusside (sodium ferricyanide)
indophenol blue
42
Modification by Searcy: using [?] (less toxic; used in the production of aspirin) instead of phenol
salicylic acid
43
MONITORING CONSUMPTION OF AMMONIA
Reaction:
Catalyst:
NH3
Glutamate dehydrogenase
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Measure a decrease in the absorbance at 340 nm
MONITORING CONSUMPTION OF AMMONIA
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Most abundant NPN compound
UREA
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Major nitrogen-containing product of protein catabolism
UREA
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Cycle
Krebs Henseleit Cycle
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– removal of the amino group
Deamination
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in retained in low conc in the circulation
Ammonia
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~90% is excreted through the kidney
UREA
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– only body fluid with very high conc of urea
Urine
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Small amount is excreted through [?] and degraded by bacteria in the intestines
sweat
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– body fluid with very low conc of urea
Sweat
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– enzyme produced by bacteria to yield ammonia
Urease
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– odor of urine due to bacteria
Ammoniacal
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freely filtered through the
glomerulus
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undergo tubular reabsorption
40 to 70%
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– preferred than creatine for renal function tests
Creatinine
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Amount of urea reabsorbed is dependent on
urine flow rate
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: clearance of urea is proportional to the GFR
Rapid flow rate
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- ↓tubular reabsorption
RAPID
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- ↑reabsorption
SLOW
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Dehydration/↓Water
SLOW
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- ↑excretion in urine
RAPID
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- ↓exretion
SLOW
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- ↑ clearance of urea
- ↑ GFR
RAPID
67
- ↑blood urea nitrogen
SLOW
68
BUN is not reliable to monitor renal function because:
It is affected by the [?]
Largely affected by [?]
Large amount is [?]
body's state of hydration
protein intake and catabolism
reabsorbed in renal tubules
69
is specific but not sensitive
BUN
70
- enzymatic
BUN
71
Measurement of ammonia from urea
BUN
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- non-enzymatic
UREA
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Measurement of urea
UREA
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stability of urea in serum
up to 24 hrs at RT
several days at 2 to 6 C
2 to 3 mons. when frozen
75
inhibits urease enzyme
Fluoride and Citrate
76
contraindicated in the assay
Double oxalate (ammonium potassium oxalate)
77
Prolonged standing: [?] due to deamination
2 to 3x increase in NH3 conc
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does not interfere
Lipemia and hemolysis
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is not required
Fasting sample
80
Based on the preliminary hydrolysis of urea with urease
INDIRECT/ENZYMATIC
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Quantitation of ammonium ion liberated
INDIRECT/ENZYMATIC
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Measurement of BUN
INDIRECT/ENZYMATIC
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NH4 reacts w/ phenol & hypochlorite
BERTHELOT REACTION
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BERTHELOT REACTION
Product:
Indophenol (blue)
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NESSLERIZATION
Product:
yellow to orange product
86
Beckman BUN Analyzer
CONDUCTIMETRIC METHOD
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Based on the conductivity generated when NH4 ions & HCO3 are produced from the reaction of urease on urea
CONDUCTIMETRIC METHOD
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Reaction is monitored by a conductivity electrode
CONDUCTIMETRIC METHOD
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Based on chromatography
URASTRAT STRIP METHOD
90
Serum or plasma travels up the urastrat strip (by capillary action)
URASTRAT STRIP METHOD
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URASTRAT STRIP METHOD
Reactants:
Urease, K2CO3 BCG (bromcresol green) - tartaric acid
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URASTRAT STRIP METHOD
Product:
Blue color
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BUN mg/dL (30 mins.)
URASTRAT STRIP METHOD
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URASTRAT STRIP METHOD
Formula
Height of color change (mm) x 5 + 10
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DIACETYL MONOXIME (DAM)
Reference:
Fearon
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Diacetyl monoxime hydrolyzes in the presence of acid to produce
diacetyl (unstable)
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Diacetyl reacts w/ Urea to produce a
diazine derivative (pink / yellow)
98
DIACETYL MONOXIME (DAM)
Product
diazine derivative (pink / yellow)
99
Adaptable to autoanalyzers
DIACETYL MONOXIME (DAM)
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Reaction is highly specific
DIACETYL MONOXIME (DAM)
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– a biochemical abnormality pertaining to increase NPN compounds (Creatinine & Urea) defining GFR defect
AZOTEMIA
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– increased plasma urea concentration
UREMIA
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: related to renal circulation defect
a. Pre-renal
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Congenital Heart Failure, shock, hemorrhage, dehydration, hypovolemia
a. Pre-renal
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Increase in urea w/o an increase in creatinine
a. Pre-renal
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: defect GFR
Renal
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lesions along renal parenchyma
Renal
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Acute glomerulonephritis (AGN)
Chronic nephritis
Polycystic kidney disease
Tubular necrosis
Renal; Post-renal
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Renal; Post-renal
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Renal; Post-renal
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obstruction of urine flow
Post-renal
112
– presence of renal calculi or kidney
Nephrolithiasis
113
males
Prostatitis
114
Nephrolithiasis
Prostatitis
Tumors of the genitourinary tract
c. Post-renal
115
BUN : CREATININE RATIO
NORMAL:
10-20:1 (8 to 20 mg/dL – conventional)
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BUN : CREATININE RATIO
Conversion factor =
0.357
117
Acute tubular necrosis (↓reabsorption)
BUN:CREA ratio <10
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Low protein intake; starvation
BUN:CREA ratio <10
119
Severe liver disease
BUN:CREA ratio <10
120
Repeated dialysis
BUN:CREA ratio <10
121
Severe vomitting or diarrhea
BUN:CREA ratio <10
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Catabolic states w/ tissue breakdown
BUN:CREA ratio >10:1 with normal creatinine
123
Pre-renal azotemia
BUN:CREA ratio >10:1 with normal creatinine
124
High protein intake
BUN:CREA ratio >10:1 with normal creatinine
125
After GIT hemorrhage
BUN:CREA ratio >10:1 with normal creatinine
126
Post-renal obstruction
HIGH RATIO WITH ELEVATED CREATININE LEVELS
127
Pre-renal azotemia superimposed on renal disease
HIGH RATIO WITH ELEVATED CREATININE LEVELS
