Urobilinogen

In the body, bilirubin is transported with the blood to the liver and from there excreted with bile into the intestine. In the intestine, bilirubin becomes urobilinogen. This is then partially absorbed again via the intestinal mucosa and returns to the bloodstream. 20% of the resulting urobilinogen is thus reabsorbed, returned to the liver via the bloodstream, further degraded and partially excreted in the urine.

An increased urobilinogen concentration 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:

• due to infections
• due to some forms of blood cancer
• various autoimmune diseases (e.g. lupus erythematosus, anti-phospholipid syndrome)
• congenital damage to red blood cells or red blood dye (haemoglobin)
• Mistransfusions
• Poisoning, burns, frostbite
• artificial heart valves

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.

Causes:

• Inflammation of the liver (hepatitis)
• Cirrhosis
• Poisoning (poisons, medicines, alcohol)
• Liver tumors
• incomplete closures of the bile ducts with liver damage
• Damage to the liver in case of heart failure (blood congestion in the liver)
• other liver damage

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.

See also: Kidney disease, blood in the urine, urobilinogen