Total bilirubin

Physiologically, most of the bilirubin in the blood is so-called indirect bilirubin, a small part is so-called direct bilirubin, which is produced in the liver. The level of bilirubin can be increased for various reasons. Increased breakdown of red blood cells, e.g. in some anemias, is associated with an increase in indirect bilirubin in the blood. Both forms of bilirubin are increased in liver disease with impaired liver cell function. Direct bilirubin entering the blood causes yellow discoloration of the skin and mucous membranes or jaundice (icterus). In the case of obstruction of the bile ducts, e.g. in gallstones and tumors, mainly direct bilirubin is significantly increased, but indirect bilirubin is also increased.[5]

Under physiological circumstances, bilirubin is present in the blood in a certain amount. Experts determine normal values ​​as follows: the norm of direct (conjugated) bilirubin is less than 5.1 µmol/l and total bilirubin is 20.5 µmol/l and less [6]. In practice, total and conjugated bilirubin are determined, unconjugated is calculated by their difference. The reference range of individual laboratories may differ from the values ​​indicated, and the data in the literature are also slightly variable.

If the measured bilirubin level in the blood is higher than the normal range, you should see a doctor. Based on further clinical data and examinations, the doctor will determine what to do to bring the levels back into the normal range. The severity of the so-called hyperbilirubinemia depends on its cause.

Bilirubin is produced by the degradation of a component of the red blood pigment (hemoglobin) from aged red blood cells. It produces water-insoluble bilirubin, which is converted in the liver to water-soluble bilirubin, the so-called conjugated bilirubin, which is excreted in the bile. It then enters the small intestine with the bile and is converted into substances that are excreted in the stool and contribute to its color [7]. Recent studies suggest that it may also have antioxidant properties and help protect against cardiovascular disease.[8]

Bilirubin is found in the body in unconjugated (water-insoluble) and conjugated forms, which are formed from the unconjugated form in the liver and are water-soluble. In the blood, bilirubin is physiologically found in unconjugated (to a greater extent) and conjugated forms (to a lesser extent), and together they give the value of total bilirubin. In laboratories, the value of total and conjugated bilirubin is determined, and unconjugated bilirubin is added.