- Urobilinogen - the result of bilirubin metabolism
- Urobilinogen norms and importance in diagnostics
- Jaundice - etiology and differentiation
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Urobilinogen is produced by the breakdown of bilirubin, a bile pigment. Your doctor may check your urobilinogen level when it suspects that your liver is not working properly or that it is suffering from a blockage of the bile ducts or hemolytic anemia. What are the norms of urobilinogen in urine? What is the evidence of the increased level of urobilinogen?
Urobilinogenis a product of bilirubin metabolism. The main source of bilirubin is hemoglobin (70-80%) - a protein contained in erythrocytes whose function is to transport oxygen. The rest of the bilirubin (20-30%) comes from the breakdown of other molecules, e.g. enzymes, in the liver.
Urobilinogen - the result of bilirubin metabolism
Bilirubin in the blood combines with albumin and is thus transported to the liver. Then, in hepatocytes (liver cells), it is conjugated with glucuronic acid residues with the participation of the enzyme UDP - glucuronyl transferase.
Water-soluble bilirubin compounds are formed. They are secreted into the bile at the biliary pole of hepatocytes with the participation of a special pump. In the small and large intestine, bilirubin is converted into urobilinogens by the action of bacterial glucuronidase. About 20% of this urobilinogen is absorbed into the blood and, passing through the liver, is excreted in the bile and in a small amount also in the urine.
In the case of liver damage or increased breakdown of red blood cells, the liver cannot capture and process this amount of urobilinogens, hence their urinary excretion is increased. Urobilinogen is converted in the urine to the yellow urobilin pigment, which gives it its color. Urobilinogen remaining in the intestinal lumen (the so-called sterkobilinogen) undergoes oxidation, resulting in the formation of a brown pigment - sterkobilin.
Urobilinogen norms and importance in diagnostics
The determination of the concentration of bile pigments in the urine is of diagnostic importance. Inadequate urobilinogen and bilirubin values in your urine may be a sign of liver disease. The norm of urobilinogen in the urine is<1 mg/dl. Poziom podwyższony może świadczyć o hemolizie, tzn. zwiększonym rozpadzie krwinek czerwonych, stanach zapalnych wątroby, marskości wątroby.
The urobilinogen concentration below indicates mechanical jaundice. Bilirubin is a pigment that should not normally appear in the urine. Its presence may also indicate liver pathologies, increased breakdown of red blood cells or urolithiasis.
The determination of the bilirubin level in the blood is also very important. We distinguish between direct and indirect bilirubin - that is, conjugated with glucuronic acid. The determination of these parameters is of particular importance in determining the etiology of jaundice.
Jaundice - etiology and differentiation
Jaundice is a yellowish discoloration of the sclera, mucous membranes and skin caused by the build-up of bilirubin in the tissues. Clear jaundice in adults is manifested at a bilirubin concentration of about 2.5 mg / dl. The yellow discoloration first appears on the sclera, then on the skin. It resolves in reverse order. If we are dealing with unconjugated hyperbilirubinemia - then the cause is probably in front of the liver - e.g. haemolysis, drugs, Gilbert's syndrome, Crigler-Najjar syndrome. The results of biochemical tests of liver function in these diseases are within the normal range. The stools are dark and the urine color is normal.
In conjugated hyperbilirubinemia, elevated bilirubin levels are usually associated with abnormal liver chemistry tests. The cause then probably lies in the liver (e.g. viral hepatitis, drugs that damage the liver, autoimmune diseases, toxic damage) or in the extrahepatic bile ducts (extrahepatic cause).
With extrahepatic jaundice - and sometimes hepatic jaundice - the stools are discolored, dark urine, persistent itching of the skin may occur, worsening after warming up or going to bed.