Bilirubin total

Why this test?

• For the diagnosis of various blood diseases in which increased destruction of erythrocytes occurs: sickle cell anemia, spherocytosis, sideroblastic / pernicious anemia.
• To assess the condition of the liver (integrity of its cellular elements).
• To detect hepatitis and its severity.
• To ensure the normal patency of the bile ducts.
• For the diagnosis of physiological and hemolytic jaundice of newborns.
• For the diagnosis of certain diseases of the pancreas, as well as other organs and tissues related to the biliary tract.
• To assess the severity of the patient's condition in case of poisoning by substances that cause hemolysis of erythrocytes.

In what cases is it prescribed?

• With symptoms of blood diseases.
• When it is necessary to assess the functional state of the liver.
• Jaundice, in particular in newborns.
• When diagnosing liver diseases.
• When assessing the function of the biliary tract.
• If viral hepatitis is suspected.
• When a patient with liver disease is being clinically monitored.
• With symptoms of biliary tract obstruction.
• When observing the condition of a patient who has been poisoned by certain chemical substances.

Test information

This test is intended for quantitative determination of total (direct + indirect) bilirubin content in blood serum.

Bilirubin is a breakdown product of hemoglobin. It has an intense yellow-brown color. In this regard, bilirubin itself and the products of its metabolism give bile, feces, and urine the appropriate color.

Hemoglobin is the main part of erythrocytes (red blood cells). Its function consists in the delivery of oxygen to the tissues from the respiratory organs and the return transport of carbon dioxide. The need to break down hemoglobin and remove its breakdown products arises in connection with the process of constant renewal of erythrocytes in the blood.

Red blood cells have a limited lifespan, which averages 90-150 days. Erythrocytes with reduced viability are recognized by cells of the reticuloendothelial system, absorbed by them and broken down into enzymes. The reticuloendothelial system is a special tissue that is located in various parts of the body and performs an immune function. The organs of their special concentration are the spleen, lymph nodes and bone marrow. As a result of the splitting of hemoglobin, indirect (unbound) bilirubin is formed, which is then released into the circulating blood. About 1% of circulating erythrocytes break down in a person per day with the formation of 100-250 mg of bilirubin.

The next stage of bilirubin transformation takes place in the liver. Liver cells «capture» it from the blood, bind it to another metabolic component (glucuronic acid) and turn it into direct, or linked, bilirubin. The attached glucuronic acid gives bilirubin the ability to dissolve in liquid, which allows it to dissolve in bile, after which it is first excreted in the intestine, and then removed from there together with feces.

There should be only a small amount of indirect bilirubin in the blood, which corresponds to the normal process of transporting this substance from the places of its formation (reticulo-endothelial system) to the liver. However, at some stages of bilirubin metabolism, metabolic disorders may occur, in which its concentration in the serum increases. This is called hyperbilirubinemia (excess of bilirubin in the blood). If there is too much bilirubin in the blood, it can penetrate from the bloodstream into the surrounding tissues, which will lead to the symptoms of jaundice: a yellow tint of the skin, sclera and visible mucous membranes.

There are three main types of bilirubin metabolism disorders in the body that lead to its accumulation in the blood.

Increased hemolysis of erythrocytes. This occurs in diseases when still young red blood cells are destroyed, and the proportion of erythrocytes subject to hemolysis increases. Such abnormalities include some blood diseases in which the formation of not fully viable erythrocytes occurs (sickle cell anemia, spherocytosis, sideroblastic anemia, pernicious anemia), immune aggression against normal erythrocytes (hemolytic disease of newborns), etc. In addition, hemolysis of erythrocytes can increase as a result of the toxic effect on blood cells of some chemicals. The increased breakdown of erythrocytes, in turn, leads to the need for enzymatic cleavage of a larger amount of hemoglobin in the cells of the reticuloendothelial system. At the same time, an additional volume of indirect bilirubin is formed, which is subsequently released into the bloodstream. As a result, the level of bilirubin is increased.

Violation of the functional and / or anatomical integrity of liver cells. It is caused by diseases in which liver cells are affected, the most common being viral hepatitis. In addition, it can occur with acute and chronic effects of toxic substances: alcohol, drugs, chemicals kats used in household and industrial production. Such violations entail an increase in the permeability of the outer membrane of liver cells or its complete destruction. As a result, the contents of liver cells enter the systemic bloodstream. Since they always contain a large amount of bilirubin, it also enters the bloodstream, which leads to hyperbilirubinemia.

An obstacle to the free passage of bile through the biliary tract before it enters the intestines. This happens due to the fact that the bile ducts are compressed due to the deformation of the tissues that are in the immediate vicinity of them (tumors, enlarged lymph nodes, scar changes), or due to the slowing down of the motor activity of the bile ducts (dyskinesia). Such disturbances can lead to an increase in the pressure of bile inside the bile capillaries, their constriction (up to microtears) and excessive permeability of the walls of the biliary tract, which is accompanied by the penetration of bile components into the blood and leads to an increase in the level of bilirubin.