Urobilinogen is a colorless substance that is formed as a result of a decrease in bilirubin levels.
All of us are aware of the fact that the liver is a really important organ in the body. Among other vital functions, the liver is also responsible for the regulation of blood sugar levels. Additionally, it has an essential role to play in the production of a digestive juice called bile, which in turn helps in the digestion of different foods that are consumed. The destruction, aging, death and degradation of red blood cells lead to the formation of a yellow colored waste known as bilirubin. The decomposition of red blood cells takes place in the liver. Thus, it can be inferred that the liver also performs the function of eliminated the byproduct bilirubin from the body, either through stools or occasionally via urine.
A large percentage of the urobilinogen that is formed during the process of bilirubin production is excreted from the body, while a portion of urobilinogen is put back into circulation after being reabsorbed into the body. It is then ultimately removed from the body as urobilinogen in urine. This process is called ‘enterohepatic urobilinogen cycle.’
Hemolysis is a condition which causes increased destruction of the RBCs. This results in increased formation of bilirubin, which in turn causes excessive quantities of urobilinogen to form in the gut. The presence of a serious liver condition like hepatitis can affect the ability of the liver to eliminate bilirubin and urobilinogen, resulting in the interruption of this ‘intrahepatic urobilinogen cycle’, which can then lead to accumulation of increased quantities of urobilinogen. These excessive levels of urobilinogen get turned into a yellowish substance known as urobilin, which then results to elimination of yellow colored urine. Additionally, urobilinogen that is found in the intestines undergoes oxidation leading to the formation of brown colored stercobilin. This is what gives the stools, their distinct color.
Biliary obstacles can lead to decreased presence of bilirubin in the intestines, which eventually leads to reduced amounts of urobilinogen. This means that limited quantities of urobilinogen are now available for reabsorption and elimination, leading to reduced presence of urobilin in urine. Also, the levels of bilirubin found in circulation are greatly enhanced which are later released through the kidneys. Such anomalies and changes that occur due to biliary obstruction can cause the formation of pale fecal material and pigmented urine.
Causes of abnormal urobilinogen in urine levels
- It is common to detect normal amounts of urobilinogen in urine. However, high level of urobilinogen in urine is abnormal and requires treatment.
- There are a number of reasons which can result in excessive amounts of urobilinogen in urine, including the presence of abnormalities such as hemolytic anemia, restricted liver function, liver cirrhosis, excessive degradation of red blood cells, poisoning, hepatic infection, overuse of the liver and increased urobilinogen production and re-absorption.
- The consumption of drugs like ascorbic acid or ammonium chloride, which raise the acidity of urine, and the occurrence of certain disorders like congenital enzymatic jaundice can result in low levels of urobilinogen in urine
- The bacteria that occur in the intestines can be destroyed due to full obstructive jaundice or treatment with a wide range of antibiotics. This may result in reduced or nil production of urobilinogen in the gut or obstruct the passage of bilirubin into the gut. Such activities can also ultimately lead to low urobilinogen in urine levels
Diagnosis of urobilinogen in urine
The levels of urobilinogen in urine are verified with the help of a urine test, which also help in the detection of liver conditions and abnormalities. The urobilinogen in urine levels along with bilirubin levels are taken into consideration during the diagnosis and differentiation of different types of hepatitis
The urine test is carried out with the help of paper strips that have stable diazonium salt. Contact of urobilinogen in urine with the strips will then result in a reddish azo compound.
Another method to detect urobilinogen in urine is a process called urinalysis, which involves a complete analysis of the urine sample.
Evaluation of the urine test results
- The usual rate of urobilinogen in urine removal is understood to be at 1 mg urobilinogen/dL of urine, wherein the urobilinogen in urine concentration is quite low at below 17 micromol/L, or ranging from 0.2 mg/dL to 1.0 mg/dL
- When the levels of urobilinogen in urine are higher or lower than normal or when urobilinogen in urine is absent, then it is believed to be pathological. One may note that the lack of urobilinogen in urine may not be observed with the help of such urine test strips.
- The different color combinations seen in the test strips, help in the evaluation of the levels of urobilinogen in urine. A lab agent is normally more equipped to evaluate the test results.
- One has to remember the following facts while evaluating the results of a urine test:
- Extended exposure of the urine sample to light can give incorrect or false negative test results.
- Presence of diagnostic or therapeutic dyes can give higher than normal or false positive results.
- High bilirubin levels can cause excessively yellowish urine
- High concentration of formaldehyde in urine can yield false or no results