Urobilinogen is produced from bilirubin, a degradation product of red blood dye (hemoglobin).
It is usually excreted in very small amounts in the urine.
In the body, bilirubin is transported with the blood to the liver, from which, after a small chemical change, it is excreted in the bile and thus into the intestine.
With an increased formation of bilirubin, even larger amounts of bilirubin enter the intestine.
In the intestine, the bilirubin then becomes urobilinogen. This is then absorbed via the intestinal mucosa and enters the bloodstream.
20% of the urobilinogen are reabsorbed, fed to the liver via the padering vein, further degraded and also partially excreted via the urine.
An increased concentration of urobilinogen in the urine is usually a sign of liver damage or the increased breakdown of red blood cells (hemolysis).
If a gallstone or tumor blocks the bile flow, this can often be seen in a reduction or by the absence of urobilinogen in the urine.
In healthy humans, the range of urobilinogen concentrations of urine ranges from 0.1-1.8 mg/dl (1.7-30 micromol/l). Concentrations above 2.0 mg/dl (34 micromol/l) are considered pathological.
Urine test strips show a positive result only at an increased concentration.
Possible causes for an increase in the urobilinogen value:
Severe hemolysis (increased breakdown of red blood cells)
They can be triggered by several factors:
Diseases or damage to the liver
In damaged liver cells, the urobilinogen absorbed from the intestine is excreted to a lesser extent in the bile. It is increasingly transferred to the blood and urine.
Bypass of the liver (blood from the intestine flows past the liver)
Normally, the blood coming from the intestine and thus also the urobilinogen flows almost completely through the so-called portal vein into the liver. In the case of cirrhosis of the liver or a blockage of the portal vein, large amounts of blood often flow past the liver. Thus, the urobilinogen cannot be broken down and enters the urine via the kidneys.