One of the goals of biochemical analysis as the main diagnostic tool is to determine the presence of bilirubin in the urine along with other substances. In healthy people, this enzyme is contained in the urine in such small amounts that traditional reagents do not detect it, and therefore it is commonly believed that the norm is the absence of bilirubin in the urine. Otherwise they talk about bilirubinuria. Consider this deviation in more detail, but first, in a simplified form, we will analyze the metabolism of the enzyme.
Where does bilirubin come from?
Human blood contains red corpuscles (erythrocytes), some of which die all the time and are replaced by new ones. During their "death", these bodies secrete hemoglobin, which breaks into two components: the heme molecule and globin chains. Hem, in turn, is exposed to enzymes and becomes indirect bilirubin, a fat-soluble toxic substance that can penetrate cells and interfere with them to function normally.
Nature provides a mechanism for converting indirect bilirubin in a straight line (water-soluble). It happens in the liver. Then, along with the bile, the enzyme is discharged through the duct to the duodenum.
If liver function is violated, direct bilirubin is found in the urine, and before that it is thrown from the bile into the blood and enters the kidneys. An indirect fraction of the enzyme can not penetrate into them, since it is not water-soluble.
Causes of bilirubin in the urine
Bilirubinuria is a symptom of impaired liver function due to:
- mechanical jaundice (duct through which bile from the liver is excreted into the small intestine, narrows - usually due to inflammation of the pancreas);
- inflammation of the liver (hepatitis) of a viral, bacterial or toxic nature;
- cirrhosis of the liver ;
- metastases in the liver;
- liver injury.
In all these cases, urinalysis shows only direct bilirubin, which the liver failed to excrete with bile in the intestine, because is sick, and the enzyme has got into the blood and kidneys. The blood test for direct bilirubin is also above normal.
At the same time, there are disorders in which there is an overabundance of indirect bilirubin (with hemolytic anemia, for example), and then a blood test shows it, and urine analysis does not.
Determination of bilirubin in the urine
To identify the bile enzyme use several methods:
- Rosina sample - 2-3 ml of urine layered 1% solution of iodine on alcohol. If a green ring appears on the border of the two liquids, then bilirubin in the urine is elevated (that is, present).
- The Fouche test is carried out with a solution of barium chloride (15%): in an amount of 5 ml add it to a test tube with 10 ml of urine. Both liquids are mixed and then passed through a filter. Then a Fuchet reagent drips onto the filter. The appearance of green crystals means that bilirubin in the urine is present.
Symptoms of bilirubinuria
Because the reasons for which bilirubin in the urine is elevated, associated with liver disease and fermenting the enzyme into the blood, a typical companion of bilirubinuria is jaundice . In the patient, sclera of the eyes, as well as the mucous membranes and skin integuments acquire a yellowish tinge that is visible to the naked eye.
Hepatic diseases are accompanied by heaviness in the hypochondrium (right), increased body temperature, bitter eructations and nausea. The feces become light in color, and urine on the contrary acquires a darker shade. Itching may occur or a hepatic colic may occur. If several of these symptoms are found, the doctor should be consulted immediately, as bilirubinuria is a sign of a serious liver disorder that does not pass by itself.
Depending on the disease (the initial causes of bilirubin in the urine), the appropriate treatment is prescribed. In addition to drug therapy, it is appropriate, and even necessary, a diet.