Urine for Bilirubin in Urine (Bilirubinuria)

Sample
- The sample is urine.
- A random sample can be taken.
Precautions
- A fresh urine sample is needed.
- Store at 2 to 8 °C for no longer than 24 hours.
- Avoid urine to light.
- Exposure to light urine will decrease the bilirubin.
- The false-positive result is seen in the metabolites of drugs like phenazopyridine.
- The substances which color the urine red or turn red in the acid medium like:
- Chlorpromazine.
- Phenothiazine.
- Indol.
- Pyridium
- The substances which color the urine red or turn red in the acid medium like:
- False-negative results are seen:
- With the ascorbic acid intake.
- Oxidation of bilirubin to biliverdin.
- Increased nitrite concentration.
- Hydrolyzation of bilirubin diglucuronide to free bilirubin.
Indications
- Diagnose hepatitis.
- Diagnose any liver damage.
- Monitor the treatment of hepatitis.
Pathophysiology
- The detectable amount of bilirubin is not found in the urine.
- Breakdown of hemoglobin leads to bilirubin formation, which goes to the liver.
- From the liver excreted into the bile.
- Excretion of bilirubin is seen in obstructive jaundice and not in hemolytic jaundice unless there is liver damage.
- Following the diagram explains bilirubin metabolism and its excretion.
- Urine bilirubin is the early sign of :
- Hepatocellular disease.
- Intra or extrahepatic biliary obstruction.
- Bilirubin appears in the urine before other signs of hepatitis appear.
- Bilirubin’s presence or absence in the urine is helpful for clinical jaundice.
- Bilirubin is the major component of bile.
- If there is an obstruction to the bile, that will lead to conjugated hyperbilirubinemia.
- Conjugated bilirubin is water-soluble so that it will appear in the urine.
- So the presence of bilirubin in urine indicates defects after conjugation and defects in excretion.
- Bilirubin is a yellowish pigment in the bile which is produced by the liver.
- Bilirubin in urine color urine = dark yellow or orange.
- This test measures the amount of bilirubin excreted in the urine.
- The presence of bilirubin in the urine indicates jaundice.
Normal
- Normally bilirubin is absent in the urine (0 to 0.02 mg/dL).
- Even traces indicate liver disease like hepatitis.
Procedure for bilirubin in the urine:
- Fouchet’s or Ferric chloride reaction:
- Add urine to barium chloride, and it will form barium sulfate precipitate containing bilirubin.
- Barium sulfate + bilirubin filter and get the precipitate.
- Add ferric chloride (Fouchet’s solution) to the above precipitate.
- Bilirubin oxidized to biliverdin, which gives green-blue color.
Comparison of the Fouchet’s reaction and Diazo reaction:
Characteristics | Fouchet’s reaction (FeCl3) | Diazo reaction |
The sensitivity of the tests | Many other compounds give a positive reaction with FeCL3 with different colors. |
A tablet test is more sensitive than a dipstick Tablet test = 0.2 to 0.4 mg/dL Dipstick test = 0.05 to 0.1 mg/dL |
False-negative result | Oxidation of the bilirubin in case of delayed testing |
|
False-positive result |
|
Chlorpromazine |
- Dipstick method:
- There is a dipstick impregnated with a diazo reagent.
- this method detect the concentration of 0.5 mg/dL or greater.
- Insert the strip in the urine no longer than one second.
- After 60 seconds, the Diazo reagent reacts with bilirubin at an acidic pH.
- A pink to red-violet color is produced.
- The intensity of the color depends upon the concentration of the bilirubin in the urine.
The various strips detection level:Type of the strip The detection level of bilirubin Ictotest 0.05 to 0.1 mg/dL Multistix 0.4 to 0.8 mg/dL Chemstrip 0.5 mg/dL
Increased urine bilirubin is seen in:
- Hepatitis and liver diseases are caused by infection or exposure to toxic agents ( cirrhosis ).
- Obstructive biliary tract disease.
- Liver or biliary tract tumor.
- Septicemia.
- Hyperthyroidism.
- Gallstones.
- Metastatic tumor in the liver.
- Drugs
- Dubin-Johnson syndrome.
- Rotor syndrome.
Urine Bilirubin/urobilinogen differential diagnosis
Test | Normal | Conjugated (Direct) hyperbilirubinemia | Unconjugated (Indirect) hyperbilirubinemia | Conjugated (Direct) hyperbilirubinemia |
Etiology | Biliary obstruction | Hemolysis | Hepatitis (liver injury) | |
Urine bilirubin | negative | positive (Increased) | Usually absent | positive |
Urine urobilinogen | positive / negative | Absent | Positive (Increased) | positive (+++) |
- Urine bilirubin is negative in hemolytic disease.
Bilirubin (urine and blood) in various types of jaundice:
Type of the jaundice | Etiology | Urine bilirubin | Urine urobilinogen | Blood bilirubin | Fecal appearance |
Hemolytic or prehepatic |
|
Negative (Usually absent) | Increased | Raised | Dark brown |
Hepatic or hepatocellular |
|
Increased (variable) (+ or -) |
Increased (++) |
An increased, variable amount | Normal or pale |
Post-hepatic or obstructive |
|
Increased (+++) | Absent (or very low) |
|
Clay-colored, acholic |
Normal urine picture:
Physical features | Chemical features | Microscopic findings |
|
|
|
I think there is a mistake in the table comparing bilirubin and urobilinogen in the urine.
in obstructive jaundice, the urobilinogen should be absent/reduced, not increased. Whereas in hemolytic anemia, the urobilinogen is increased, not negative
Table corrected, thanks for the comment.