Direct bilirubin in the blood

Direct bilirubin in the blood is one of the types of important bile tetrapyrroles - pigments. In addition to direct bilirubin, there is another type - indirect. First of all, let us recall what bilirubin is. It is a derivative of bilinogen with an oxidized nucleus, yellowish-red in color. Myoglobin, peroxidase, catalase and hemoglobin periodically disintegrate, and the products of this process are formed into tetrapyrroles - pigments. The breakdown is carried out by specific cells that are located in the hematopoietic organ - the bone marrow and to a greater extent in the liver and in the lymphoid organ - the spleen. Almost all bilirubin can be considered the "brainchild" of erythrocyte hemoglobin. When erythrocytes perform their function and begin to "age", they are transformed in the spleen into a free insoluble form of bilirubin, which the kidneys cannot remove due to its high density. Albumin, which is generally famous for its "transport" functions, comes to the rescue, it binds toxic indirect bile pigment and carries it directly into the liver ducts with the blood flow. Direct bilirubin in the blood is obtained as a result of binding free, indirect pigment with a specific acid - glucuronic. In this form, bilirubin is no longer dangerous for the human body, it dissolves well in an aqueous environment and is excreted normally with feces, and also partially by the kidneys. Direct bilirubin is also called because it is easy to detect in laboratory tests using reagent staining. Indirect pigment is stained only after the separation of proteins into sediment under the influence of alcohol-containing liquids.

Reference values (norm) for direct bilirubin content in blood serum are 0-0.2 mg/dl or 0-3.4 μmol/l.

Direct bilirubin in the blood is the main marker showing the extent of liver damage, as well as the condition of the external and intrahepatic ducts. By determining the level of direct bilirubin in the blood, it is possible to identify hidden forms of latent hepatitis (jaundice), when the sclera and skin of a person are not colored in the symptomatically usual yellowish color. Direct bilirubin in the blood also helps to determine the etiology of mild attacks, similar in symptoms to cholelithiasis. Such mild symptoms are often similar to painful sensations in the ulcerative process in the initial section of the small intestine - the duodenum, with renal colic and others. When direct bilirubin in the blood is higher than the specified norm, this indicates stones in the bile ducts, an increase in direct bilirubin is especially characteristic in cases where the stone tightly closes the narrowed duct. Also, an increased direct pigment in the blood signals possible tumors - gallbladder or liver, hepatitis, the likelihood of degeneration of parenchymatous liver tissue into fibrous - cirrhosis. Pregnant women may also have increased direct bilirubin if the process of bearing is accompanied by severe toxicosis. Protein degeneration of liver cells - atrophy, hepatitis associated with syphilis, an inflammatory process in the intrahepatic ducts - cholangitis (angiocholitis), drug-induced jaundice, intoxication with phosphorus drugs - this is not a complete list of diseases indicated by direct bilirubin in the blood, exceeding the norm. If the disease is chronic and proceeds for quite a long time in a latent form, a blood test may show an excess of the norm of both direct and indirect bilirubin.

Direct bilirubin in the blood is determined by analyzing blood serum. The study is conducted in the morning, on an empty stomach. An increase in direct bilirubin is called hyperbilirubinemia.

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Reasons why direct bilirubin is elevated

• all types of viral hepatitis;
• infectious liver diseases;
• all problems associated with poor functioning of the gallbladder (cholangitis, cholecystitis);
• cholestatic cirrhosis - biliary;
• narrowing of the intrahepatic ducts, obstruction, due to a tumor of the pancreas;
• helminthiasis;
• oncoprocesses;
• hereditary hepatosis - Rotor syndrome;
• pigment hepatosis - Dubin-Johnson syndrome.

Direct bilirubin in the blood together with its more toxic brother - indirect bilirubin actually make up the pigment of bile, that is, bilirubin. In the case when the amount of non-toxic bilirubin exceeds the normal limits, its excess seeks to find an outlet in the skin, the sclera of the eyes. The yellowish tint that they acquire is an indication of an excess of the direct bilirubin norm.