Urobilinogen in Urine

Urobilinogen is a product of bilirubin  a colorless substance  resulting from the breakdown of bilirubin. Resident bacteria within the intestines converts urobilinogen into stercobilin. Some urobilinogen is sent from intestine to kidney for excretion while some of them get converted to urobilin. The yellow color of the urine is regulated by urobilin. On the other hand, feces get its brown color with help of stercobilin.

Bilirubin which results in urobilinogen in turn is a product of hemoglobin breakdown. Breakdown of RBC causes unconjugated form of bilirubin. Unconjugated bilirubin reaches the liver where it gets converted into conjugated form.  This soluble bilirubin becomes bile component; bile is a fluid produced in the liver and gets deposited in the gallbladder. Consuming high fat food will cause the gallbladder to secrete bile to aid in fat digestion process. This bile then transfers to the small intestine. After reaching the intestine bilirubin undergoes conversion again due to resident bacteria which are present in the intestine. This conversion is what leads to production of urobilinogen.

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Some of this urobilinogen is used by the intestine while some are transferred to the kidney for egestion. Some amount of urobilinogen gets converted to urobilin which is expelled from the body through urine. The amount which is not absorbed by intestine often transforms into stercobilin and is egested through feces.

Increased urobilinogen amount in the urine often indicates hyperbilirubinemia wherein bilirubin is present in excessive amount in the blood. This condition is also sometimes recorded in newborn babies. In this case bilirubin is in unconjugated form and gathers in child’s brain; this may cause seizures, ocular issues and also mental retardation. Liver inflammation and cirrhosis are other conditions which may increase the amount of this substance significantly. If there is obstruction in the bile passageway the level of urobilinogen may become anomalously low.

Urobilinogen in Urine – Causes and Clinical Significance

The amount of urobilinogen in urine may increase due to present of hemolytic process, for example hemolytic anemia. Other factors that causes increased amount of this substance may include hepatitis infection or cirrhosis. Low level of urobilinogen in urine may occur due to complete obstructive jaundice. Some treatments that include broad spectrum antibiotics which can destruct bacterial flora in the intestine can also cause low urobilinogen in urine. Decreased urobilinogen may also be result of congenital enzymatic jaundice which is the aforementioned hyperbilirubinemia syndrome. Drugs that acidify the urine also truncate the level of this substance in urine. These drugs may include ascorbic acid or ammonium chloride.

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Excessive break down of red blood cells that cause hemolytic anemia also causes increased level of urobilinogen in urine. Other situations include overburdening of liver, increased production of urobilinogen, restricted functioning of the urine, liver cirrhosis, hepatic infection, etc. Measuring range of urobilinogen is 0 to 8 mg/dl. Normal range off urobilinogen is below 17 umol/l, which less than 1 mg/dl.

 Test for Urobilinogen in Urine

Urobilinogen test is based on Ehrlich Aldehyde Reaction. The urine may have pink-reddish color due to Para-dimethylaminobenzaldehyde reaction with urobilinogen. Chemical reagent strip response of urine upsurges with rise in the body temperature. However, the best temperature for testing this substance is 22 degree to 26 degree Celsius. Fresh sample of urine is always better for obtaining best results. Watson Schwartz quality test can be used to confirm results that are equal to or greater than 2.0 Ehrlich units. This test can differentiate between porphobilinogen and urobilinogen.

  • False positive urobilinogen result

False-Positive reaction of urobilinogen can occur with chemical reagent strip technique in case of presence of substance that may react with Ehrlich’s reagent. These substances may include sulfonamide or para-aminosalicyclic acid. Medicine with Azo dyes has gold color that can disguise the reaction leading to false positive reaction. 

  • False-Negative urobilinogen results

If the urine sample has been kept in room temperature exposed to light for long time then false-negative result may occur due to instability of urobilinogen during chemical reagent strip test. Also in case when formalin is present, false negative urobilinogen result may be recorded.

Urobilinogen in urine – causes

One of the most common causes of urobilinogen in urine is hemolytic anemia caused either due to hemolysis in blood vessels or other region of the human body. RBC breakdown in blood vessel is also referred to as intravascular hemolysis while RBC breakdown in other body part is referred to as extravascular hemolysis. To understand whether high urobilinogen rate in urine is due to this condition it is better to track the symptoms. Some of the symptoms of this condition include shortness of breath and fatigue or lethargy. There are also chances of jaundice and increased risk of gallstone development and pulmonary hypertension.

Since there are possibilities that increased urobilinogen in urine may be indication of underlying physical condition as explained above, it is essential to undergo diagnosis if you experience urine changes. You should meet your doctor if you suffer from smelly urine or notice changes in urine color.

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