Urine for Urobilinogen and Ehrlich Reagent

Urine for Urobilinogen

What sample is needed for urine urobilinogen?

1. The test is done in the urine.
2. A random sample can be taken.
3. 2 hours fresh urine sample can be used, kept cool, and protected from the light.
4. The sample is stable at 2 to 8 °C for 24 hours when urine is kept in the dark.
5. Don’t expose urine to light or store it at room temperature.
6. 2 to 3 hours postprandial after the noon meal is the best sample.

What are the Indications for urine urobilinogen?

1. To assess liver function.
2. This is the earliest sign of liver disease.
3. This is positive in hemolytic anemia.

What are the precautions for estimating urobilinogen in urine?

1. False-positive test seen in:
2. Drugs containing azo dyes:
   1. Phenazopyridine.
   2. Nitrofurantoin.
   3. Riboflavin.
   4. p-aminobenzoic acid.
   5. Highly colored pigments and their metabolites.
   6. Methyldopa.
3. False-negative test seen in:
   1. Oxidation of urobilinogen to urobilin.
   2. Formalin preservative.

How will you discuss the pathophysiology of Urobilinogen?

1. Hemoglobin breaks into bilirubin and enters the intestine, and thereby, the action of bacteria is transformed into urobilinogen.
   1. Urobilinogen in the intestine is excreted as urobilin, giving urine a yellow color.
2. Urobilinogen in the intestine is reduced to brown stercobilin, giving stool color.

1. Urobilinogen is absorbed into the portal circulation, reaches the liver, metabolizes, and excreted into the bile.
2. Urobilinogen traces escape removal by the liver and is carried to the kidney and excreted in the urine.

What are the characteristics of urobilinogen?

1. Urobilinogen is colorless.
2. The intestinal bacteria oxidize urobilinogen to Urobilin, which is a brown pigment.
3. Its absence indicates obstructive jaundice.

What is the normal urobilinogen in urine?

• Random sample = < 1 mg/dL.
• 24-hour sample = 0.5 to 4 mg/dL.

Another source

• Urine = 0.5 to 4.0 Ehrlich units/day.
• Feces = 75 to 400 Ehrlich units/day.

Another source

• Urine urobilinogen  =  0.1 to 1.0  Ehrlich units /2 hours.
• One Ehrlich unit = approximately 1 mg of urobilinogen.

How will you detect urobilinogen in urine?

1. Add a fresh urine sample to Ehrlich’s reagent.
2. Ehrlich’s reagent:
3. Principle:
   1. Urobilinogen + p-dimethylamino benzaldehyde (Erhlich’s reagent) = Form red color.
   2.  Ascorbic acid is added as a reducing agent to keep urobilinogen in a reduced state.
   3. The addition of saturated sodium acetate stops the reaction.
4. Preparation of the reagent Ehrlich’s reagent:
   1. p-Dimthylaminobenzaldehyde (4-dimethylaminobenzaldehyde) =  4 grams.
   2. Hydrochloric acid, concentrated = 40 mL.
   3. Distle water = 160 mL.
      1. Take the 4-dimethylamino benzaldehyde dissolve in distle water.
      2. Add the conc HCL and mix well.
   4. This is stable at room temperature in a colored bottle, especially dark brown. Protect it from sunlight.
5. The procedure of the Ehrlich’s reaction:
   1. Take two test tubes.
   2. Label one as a test (T)  and the other for comparison (B).
   3. Add 5 ml of freshly voided urine to each test tube.
   4. Add 0.5 mL of Ehrlich’s reagent to test (T).
   5. Add 0.5 mL of conc HCL to the B test tube and mix.
   6. Leave both test tubes at room temperature for 5 minutes.
   7. Note the red color in the test (T) tube.
      

      Urobilinogen by Ehrlich’s reagent

6. For feces, the same method can be  used except:
   1. Stool Aquos extract is treated with alkaline ferrous hydroxide to reduce urobilin to urobilinogen.
   2. Now add Ehrlich’s reagent.

What are the causes of increased Urobilinogen in urine?

1. Cirrhosis due to:
   1. Alcoholic cirrhosis.
   2. Viral diseases.
   3. Chemicals.
2. Biliary obstruction.
3. Biliary tract infection, cholangitis.
4. Hepatotoxic drugs, e.g.aminosalicylic acid, Phenothiazine, and penicillin,
5. Due to increased RBCs destruction:
   1. Hemolytic anemia.
   2. Pernicious anemia.
   3. Malaria.
   4. Drugs.
6. Acute hepatitis.
7. Pulmonary infarction.
8. Hematoma.
9. Excessive ecchymosis.

What are the causes of decreased Urobilinogen in urine?

1. Gallstones.
2. Biliary obstruction.
3. Biliary tract infection (severe).
4. Pancreatic cancer (head of the pancreas)
5. Drugs, e.g., Aspirin, Chloramphenicol, Insulin, phenytoin, Streptomycin, tetracycline, Methyldopa, and sulphonamide.

Give the differential diagnosis of urine bilirubin and urobilinogen in various conditions?

Normal urine picture:

Questions and answers: