1S [LAB]: Bilirubin Flashcards
A waste product of the hemoglobin catabolism
Bilirubin
In order to be conjugated, the albumin attached to the unconjugated bilirubin through what bond?
Covalent bond
This is responsible for the transfer of glucuronic acid to unconjugated bilirubin
uridine diphosphate-glucuronosyltransferase (UDGPT)
The direct bilirubin is converted into ___ by the gut bacteria
urobilinogen
80% of urobilinogen is excreted in the ___ in the form of ___
feces
stercobilin
2% of urobilinogen is excreted in the ___ in the form of ___
urine
urobilin
18% of urobilinogen is excreted in the ___ and reabsorbed
enterohepatic circulation (portal duct system)
Urobilinogen is also called ___
stercobilinogen
The bilirubin test using the classic diazo reaction uses which specimen?
Urine
The end product of bilirubin mixed with diazotized sulfanilic acid in bilirubin determination of classic diazo reaction is ___
colored complex
In the bilirubin determination, this specific test is considered more reliable and uses serum as its sample
Van Den Bergh Reaction
___ may be a sign of significant hepatic obstruction and is a conjugated bilirubin covalently bound to albumin
delta bilirubin
Give the reagents in total bilirubin determination
Bilirubin
Diazotized sulfanilic acid
Accelerator
What is the end product of bilirubin added with diazotized sulfanilic acid?
2 azobilirubin
Give the reagents in conjugated bilirubin determination
Bilirubin
Diazotized sulfanilic acid
How do we determine the measure of unconjugated bilirubin?
Total bilirubin - Conjugated bilirubin = Unconjugated bilirubin
Give the composition of Diazo reagent
Sulfanilic acid + HCl and Sodium nitrite
The two methods of bilirubin determination
Malloy-Evelyn
Jendrassik-Grof
The more commonly used method of bilirubin determination
Jendrassik-Grof
Malloy-Evelyn/ Jendrassik-Grof:
Accelerator: 50% methanol
Malloy-Evelyn
Malloy-Evelyn/ Jendrassik-Grof:
Acidic pH
Malloy-Evelyn
Malloy-Evelyn/ Jendrassik-Grof:
End color: pink to purple
Malloy-Evelyn
Malloy-Evelyn/ Jendrassik-Grof:
Accelerator: Caffeine Sodium Benzoate
Jendrassik-Grof
Malloy-Evelyn/ Jendrassik-Grof:
Alkaline pH
Jendrassik-Grof
Malloy-Evelyn/ Jendrassik-Grof:
End color: Blue
Jendrassik-Grof
Why is Jendrassik-Grof the more preferred method of bilirubin determination?
*Not affected by pH change
*Not affected by protein concentration
*Optically more sensitive
*Less affected by hemolysis to a certain extent
*Has minimal turbidity and a relatively constant serum blank
Result of light to bilirubin determination
False decreased (light oxidizes bilirubin to biliverdin)
The wavelength used to determine is the sample has increased bilirubin content
450 nm
In the urine, a color of ___ or __ indicates the presence of bilirubin
Amber or brown
A physical test of the urine that determines whether the sample has excess conjugated bilirubin
Foam test
Interpret the foam test result:
White, small amount
Normal
Interpret the foam test result:
White, large amount
Possible protein
Interpret the foam test result:
Yellow, large amount
May be due to bile/ bilirubin
Reference range of urobilinogen in the urine
0.1-1.0 Ehrlich’s unit (2hrs)
Reference range of urobilinogen in the feces
75-275 Ehrlich’s unit/ 100g of fresh feces
How much urobilinogen is in 1 Ehrlich unit?
1mg
Synthetic function tests done in the liver
*Prothrombin time and other tests for clotting factors
*Vitamin K response test
*Special protein determination
Using ___ method, direct bilirubin reacts with diazotized sulphanilic acid (DSA) to form a red azo dye
Jendrassik and Grof
The absorbance of the red azo dye formed in the Jendrassik and Grof method has an absorbance of ___ and is ___ proportional to the bilirubin concentration in the sample
546 nm
directly
T/F: Indirect bilirubin will react with DSA whereas the water-soluble bilirubin will only react with DSA in the presence of an accelerator
False (direct bilirubin will react directly; indirect bilirubin will need accelerator)
The accelerator used in the bilirubin testing is ___
Cetrimide (caffeine sodium benzoate may also be used)
In bilirubin testing, setup 1 should be measured at ___ nm while setup 2 is measured at ___
550 nm
700 nm
Sample to reagent ratio in bilirubin testing
1:20
In bilirubin testing, the setups are incubated at ___ for ___ minutes
37C
5 minutes
Conversion factor for bilirubin
17.1
Reference range for conjugated bilirubin
0 - 0.2 mg/dL
Conjugated bilirubin is increased in what type of jaundice?
Obstructive jaundice
Unconjugated bilirubin is increased in what type of jaundice?
Hemolytic jaundice
Conjugated and unconjugated bilirubin is increased in what type of jaundice?
Hepatocellular jaundice
Reference range for unconjugated bilirubin
0.2 - 0.8 mg/dL
Reference range for total bilirubin
0.2 - 1.0 mg/dL
Identify the effect to bilirubin measurement:
Lipemia
False increase
Identify the effect to bilirubin measurement:
Hemolysis
False decrease
If left unprotected from light, bilirubin values may reduce by ___ to ___ per hour
30-50
If serum or plasma is separated from cells and stored in the dark, it is stable for ___ at RT, and ___ at 4C
2 days
1 week
A candidate reference method for bilirubin determination
Jendrassik-Grof
The result of diazo reagent reacted during Jendrassik-Grof
Purple azobilirubin
The reaction with the diazo reagent is terminated by the addition of what reagent?
Ascorbic acid
In the determination of urine urobilinogen, the use of ___ maintains urobilinogen in the reduced state
Ascorbic acid
In the determination of urine urobilinogen, the use of ___ minimizes the combination of other chromogens with the Ehrlich’s reagent
Saturated sodium acetate
Spectrophotometric wavelength to determine if the sample has an increased bilirubin content
450 nm
