02 UREA Flashcards
Approximate plasma concentration of urea
45-50%
Approximate urine concentration of urea
86
Urea is synthesized in the ___ from CO2 + ammonia generated during protein catabolism
liver
The urea cycle takes place in ___ and is a compartmentalized process between the ___ and ___
hepatocytes
mitochondria
cytosol
The formation of carbamoyl phosphate and citrulline takes place in the ___ of the hepatocytes
mitochondria
The formation of the urea takes place in the ___ of the hepatocytes
cytosol
The end product of the urea cycle, the urea, is released through the help of the ___ enzyme
arginase
T/F: urea is water soluble
T
How many percent of urea is reabsorbed by the proximal convoluted tubule?
40-60%
How many percent of urea is excreted in the urine?
50%
How many percent of urea is excreted in the GI tract and skin?
<10%
The urea cycle is also known as ___
Krebs-Henseleit cycle
T/F: Urea synthesis is the body’s defense mechanism to reduce the level of ammonia in the body
T
Conversion factor of BUN to urea
2.14
Conversion factor of urea to BUN
1/2.14 or 0.467
An elevated concentration of urea in the blood without symptoms
azotemia
Very high levels of plasma urea accompanied by renal failure
uremia/ uremic syndrome
A manifestation of high urea concentration through deposits in the skin which causes it to be more brown in color
uremic frost
Uremia causes which alteration in the RBC shape?
echinocytic/ Burr cells
Increased urea concentration due to decreased blood flow to the kidneys
pre-renal azotemia
Pre-renal/ Renal/ Post-renal Azotemia:
congestive heart failure
pre-renal
Pre-renal/ Renal/ Post-renal Azotemia:
shock, haemorrhage
pre-renal
Pre-renal/ Renal/ Post-renal Azotemia:
dehydration
pre-renal
Pre-renal/ Renal/ Post-renal Azotemia:
high protein diet
pre-renal
Increased urea concentration due to accumulation of urea due to damage
renal azotemia
Pre-renal/ Renal/ Post-renal Azotemia:
acute/chronic renal failure
renal
Pre-renal/ Renal/ Post-renal Azotemia:
glomerulonephritis
renal
Pre-renal/ Renal/ Post-renal Azotemia:
tubular necrosis
renal
Increased urea concentration due to urinary tract obstruction
post-renal azotemia
Pre-renal/ Renal/ Post-renal Azotemia:
renal stones/ lithiasis/ calculi
post-renal
Pre-renal/ Renal/ Post-renal Azotemia:
prostate enlargement
post-renal
Pre-renal/ Renal/ Post-renal Azotemia:
severe infection
post-renal
Pre-renal/ Renal/ Post-renal Azotemia:
high urea: normal creatinine
pre-renal
Pre-renal/ Renal/ Post-renal Azotemia:
high urea: high creatinine
renal
Pre-renal/ Renal/ Post-renal Azotemia:
“normal” urea to creatinine ratio
renal
Pre-renal/ Renal/ Post-renal Azotemia:
normal urea: high creatinine
post-renal
Normal urea to creatinine ratio
10:1 - 20:1
Normal BUN level
6-20 mg/dL
Normal creatinine level
0.5-1 mg/dL
Liver disease causes a/n ___ (increase/decrease) in plasma urea level
decrease
Increased protein synthesis causes a/n ___ (increase/decrease) in plasma urea level
decrease
Conversion factor of BUN from mg/dL to mmol
0.357
T/F: the chemical method of urea determination is nonspecific and is interfered by ammonia
F (nonspecific but NOT interfered by ammonia)
Fearon’s reaction is also known as ___ or ___
Friedman’s method
Xanthydrol method
Reagents for Fearon’s reaction
strong acid, oxidizing agent, ferric ions, thiosemicarbazide
Product of Fearon’s reaction
yellow diazine derivative
Condensation with ___ ___ ___ is also called Fearon’s reaction
Diacetyl monoxime method
T/F: condensation with diacetyl monoxime method can be used in autoanalyzer
T
The urease-Berthelot’s method of urea determination uses ___ ___ as an indicator
indophenol blue
This enzymatic method of urea determination uses Gum Ghatti and Nessler’s reagent to produce the yellow product
urease-Nessler’s method
Best method of urea determination that is best performed in kinetic method
Urease-L-Glutamate Dehydrogenase Method (GLDH)
The GLDH method is measured spectrophotometrically at what wavelentgh?
340 nm
A more specific and rapid method of measuring urea but is not routinely used
Urease-conductimetric method
Reference method for urea determination
Isotope Dilution Mass Spectrometry (IDMS)
Specimens that can be used for urea determination
Plasma
Serum
Urine
In urea determination, if plasma will be used, any additive may be used except ___ ___ and ___ ___ which interferes with urease and ammonium ions
Sodium citrate
Sodium fluoride
T/F: in BUN measurement, fasting is required
F (no fasting requirement)
Normal urea urine level
12-20 g/day
Urea is also known as ___
carbamide
Chemical formula of urea
CO(NH2)2
The more appropriate term for quantification of urea
Blood urea nitrogen (BUN)
The most frequently used method for BUN determination
Enzymatic method
In the enzymatic method of BUN determination, the urease enzyme catalyzes hydrolysis of urea and the ___ is quantified
liberate ammonium ion (NH4+)
The most common assay of BUN determination
GLDH-coupled enzymatic reaction