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Total bilirubin (Bilirubin total) is one of the key indicators of the functioning of the liver and the hematopoietic system of the body. This yellow pigment is a product of the breakdown of hemoglobin, which is formed during the destruction of old erythrocytes. The process of hemoglobin breakdown occurs in the bone marrow and spleen. After the breakdown of hemoglobin, unconjugated and direct bilirubin are formed.

Unconjugated (indirect) bilirubin is toxic to the body and is insoluble in water. Therefore, it tends to accumulate in tissues and can cause jaundice, where the skin and mucous membranes take on a yellow tint. This condition can occur when the normal level of unconjugated bilirubin in the blood exceeds the normal level.

Direct (conjugated) bilirubin is formed after the liver processes unconjugated bilirubin. It becomes water-soluble and can be excreted from the body through urine and feces. Bile acids play an important role in this, helping to more effectively remove bilirubin from the body.

Normal levels of bilirubin in the blood usually range from 0.3 to 1.0 mg/dL (milligrams per deciliter) or 5 to 17 µmol/L (micromoles per liter). Elevated levels of total bilirubin can indicate a number of problems related to liver function and the hepatobiliary system.

One of the most common causes of elevated bilirubin is hepatitis, an inflammation of the liver that can be caused by viruses, alcohol, toxins, or other factors. Another possible cause is cirrhosis, a chronic disease in which healthy liver cells are replaced by scar tissue, limiting the organ's function.

Moreover, elevated bilirubin levels can be a result of hemolytic anemias—conditions in which red blood cells are destroyed faster than they are produced, leading to the release of more unconjugated bilirubin.

To establish the diagnosis and extent of possible disorders, the doctor usually orders a comprehensive liver function test, including a biochemical blood test. Sometimes additional tests may be needed, such as a liver ultrasound, liver puncture, or other procedures.

In the case of elevated bilirubin levels, treatment will depend on the specific cause. For example, antiviral medications may be prescribed for hepatitis, symptomatic and supportive therapy for cirrhosis, and treatment aimed at correcting anemia for hemolytic anemia.

Therefore, total bilirubin is an important indicator of liver and hematopoietic system health. The value of this indicator can indicate various diseases and disorders in the body, so its level should be studied and monitored carefully.