Urine Bilirubin (Bilirubinuria)

What sample is needed for urine bilirubin?

1. The sample is urine.
2. A random sample can be taken.

What are the precautions for urine bilirubin?

1. A fresh urine sample is needed.
2. Store at 2 to 8 °C for no longer than 24 hours.
3. Even at room temperature, it converts into biliverdin.
4. Avoid urine to light. Avoid daylight or fluorescent light.
   1. Light converts bilirubin to biliverdin, which is not detected by routine methodology.
5. Exposure to light urine will decrease bilirubin.

What are the reasons for false positives?

1. A false positive result is seen in the metabolites of drugs like phenazopyridine.
   1. The substances that color the urine red or turn red in the acid medium are:
      1. Chlorpromazine.
      2. Phenothiazine.
      3. Indol.
      4. Pyridium

What are the reasons for a negative urine bilirubin?

1. False-negative results are seen:
   1. With the ascorbic acid intake.
   2. Oxidation of bilirubin to biliverdin.
   3. Increased nitrite concentration.
   4. Hydrolyzation of bilirubin diglucuronide to free bilirubin.

What are the Indications for urine bilirubin?

1. Diagnose hepatitis.
2. Diagnose any liver damage.
3. Monitor the treatment of hepatitis.

How will you define urine bilirubin?

1. The conjugated bilirubin is excreted from the kidneys and appears in the urine.
2. Unconjugated bilirubin can not pass the glomerular filtration, so it is not in the urine.

How will you discuss the pathophysiology of bilirubin metabolism?

1. A detectable amount of bilirubin is not found in the urine.
2. The breakdown of hemoglobin leads to bilirubin formation, which goes to the liver.
   1. From the liver, it is excreted into the bile.
   2. Excretion of bilirubin is seen in obstructive jaundice and not in hemolytic jaundice unless there is liver damage.

3. The diagram explains bilirubin metabolism and excretion of bilirubin in the urine.

Bilirubin metabolism and excretion of the bilirubin in urine

What is the Clinical significance of urine bilirubin?

1. Urine bilirubin is the early sign of:
   1. Hepatocellular disease.
   2. Intra or extrahepatic biliary obstruction.
2. Bilirubin appears in the urine before other signs of hepatitis appear.
3. Bilirubin’s presence or absence in the urine is helpful for clinical jaundice.
4. Bilirubin is the major component of bile.
5. If there is an obstruction to the bile, that will lead to conjugated hyperbilirubinemia.

6. Conjugated bilirubin is water-soluble, so it will appear in the urine.
7. The presence of bilirubin in urine indicates defects after conjugation and defects in excretion.
8. Bilirubin is a yellowish pigment in the bile produced by the liver.
9. Bilirubin in urine color = dark yellow or orange.
   1. This test measures the amount of bilirubin excreted in the urine.
   2. The presence of bilirubin in the urine indicates jaundice.

What is the normal urine bilirubin?

• Normally, bilirubin is absent in the urine (0 to 0.02 mg/dL or 0 to 0.34 µmol/L).
• Even traces indicate liver disease like hepatitis.

How will you check urine bilirubin?

The following tests are used to check bilirubin in the urine:

1. Fouchet’s test.
2. Strip method.
3. Tablet method.

How will you perform the tablet method?

1. In this test, bilirubin forms stable diazonium salt that produces blue-purple azobilirubin.
2. This reaction is specific to bilirubin.
3. Read the result after 60 seconds.
4. Moisture will deteriorate the reagents.
5. Always use a white dry tablet.
6. It detects the urine bilirubin level as low as 0.5 mg/dL.

How will you perform the Fouchet’s or Ferric chloride reaction?

1. Add urine to barium chloride, forming a barium sulfate precipitate containing bilirubin.
2. Barium sulfate + bilirubin filter and get the precipitate.
3. Add ferric chloride (Fouchet’s solution) to the above precipitate.
4. Bilirubin oxidized to biliverdin, which gives a green-blue color.

How will you compare Fouchet’s and Diazo’s reaction?

What is the positivity of various strip detection levels?

What are the causes of increased urine bilirubin?

1. Hepatitis and liver diseases are caused by infection or exposure to toxic agents ( cirrhosis ).
2. Obstructive biliary tract disease.
3. Liver or biliary tract tumor.
4. Septicemia.
5. Hyperthyroidism.
6. Gallstones.
7. Metastatic tumor in the liver.
8. Drugs
9. Dubin-Johnson syndrome.
10. Rotor syndrome.

What is the differential diagnosis of Urine Bilirubin/urobilinogen?

• Urine bilirubin is negative in hemolytic disease.

Bilirubin (urine and blood) in various types of jaundice:

Questions and answers: