Indirect bilirubin: norm and deviations

Bilirubin is a colored pigment produced in the bone marrow or spleen and is part of the bile. It is formed as a result of the destruction of red blood cells - blood cells, the average residence time of which is about 110 days. There are direct and indirect bilirubin. Indirect is not soluble in water, so it can be removed from the body only after its change to the soluble form in the liver - direct bilirubin. Today, we’ll dwell more specifically on indirect bilirubin - the norm, the reasons for an increase or decrease in the blood of a person, etc.

Table of Contents:
  • Norm of indirect bilirubin
  • Increase in indirect bilirubin in the blood: causes
  • Causes when indirect bilirubin is reduced

Definition of

Indirect bilirubin is an unbound and insoluble pigment form. It has a toxic effect on the tissue, so ideally it should be as low as possible in the bloodstream. The transition process of indirect bilirubin in a straight line is called conjugation, therefore the indirect form is also called unconjugated( free).

In general, the names "direct" and "indirect" bilirubin are associated with research methods. The blood, which contains a water-soluble pigment, reacts directly with Ehrlich's reagent. To detect indirect bilirubin in the blood, it is necessary to perform additional operations, so such a study can not be called direct.

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Norm of indirect bilirubin

The concentration of indirect bilirubin is not related to gender or hormonal disruptions, in other words, the rate of indirect bilirubin in the blood of women and men is the same. However, it depends on age, because children have more of this pigment in their blood, the younger they are.

The value of indirect bilirubin is calculated based on the difference between the total and direct index. The rate of indirect bilirubin = total - a straight line is usually not more than 19 micromolar per liter of blood.

In order to better navigate the results of the analysis, one should know the rate of indirect bilirubin in the blood, direct and general. For newborns, the reference values ​​of the total pigment content vary almost by day:

0-2 days: 57-198 μmol / liter;

2-6 days: 25-206 µmol / liter;

Over 6 days: 5-21 µmol / liter;

In this case, direct and indirect bilirubin in newborns should not exceed 5 µmol / liter and "Total minus 5" µmol / liter, respectively.

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Increase in indirect bilirubin in the blood: causes of

Diseases that can cause an increase in the concentration of insoluble pigment in the blood can be divided into several groups, depending on the damage to the systems and organs.

  1. The circulatory system

Indirect bilirubin rises in the blood with increased breakdown of red blood cells, resulting in the release of heme protein, which turns into an insoluble pigment. Such a deviation occurs with anemia or anemia, when the body has a deficiency of hemoglobin, which he seeks to fill by destroying red blood cells.

In this case, the patient's liver can be completely healthy, and the process of removing bilirubin from the body occurs as usual. However, the amount of incoming bile pigment is so large that the liver cannot cope with the load, resulting in elevated indirect bilirubin in the blood.

If the concentration of indirect bilirubin increases continuously, hemolytic anemia can develop into hemolytic jaundice.

Among the signs of hemolytic anemia can be identified:

  • Weakness;
  • Pallor;
  • Frequent dizziness;
  • Spleen enlargement;
  • Specific blood test results: indirect bilirubin and reticulocytes increased, direct bilirubin is normal, hemoglobin is lowered;
  • Specific urinalysis: urobilinogen is highly elevated.

It should be clarified that anemia can be congenital or acquired, these types in turn are subdivided into more specific anemia.

An increase in the level of indirect bilirubin can be caused by such infectious diseases as malaria, sepsis, etc., by taking drug complexes, by exposure to certain poisons: for example, lead, arsenic, copper salts, etc.

In newborns, high bilirubin can be caused by a dangerous hemolytic disease, which often develops in the womb.

  1. Liver

If the functions of the circulatory system are working properly and the indirect bilirubin is elevated, what does this mean? Probably, indirect bilirubin can not be transformed in the liver into a soluble form and go out together with waste products. Instead, it accumulates in the blood and tissues.

The causes of the increase in indirect bilirubin, caused by pathologies of the liver or its enzymatic system, are not so numerous. These are:

  • Gilbert's syndrome;

A genetically transmitted disease that causes an abnormality of the enzyme glucuronyltransferase, which is responsible for the transition of indirect bilirubin to a soluble form. Usually manifested in adolescence, proceeds with improvement and by the age of 50 is practically not observed.

  • Crigler-Nayar Syndrome;

The disease is manifested in newborns with severe jaundice. The glucuronyltransferase enzyme described above is completely or partially absent in liver cells.

  • Lucy-Driscol syndrome;

Disease characteristic of breastfed babies. In this case, indirect bilirubin is increased in the infant because of the presence in the mother's milk of a steroid hormone, which blocks the work of the enzyme necessary for the conversion of the indirect bilirubin into a straight line.

  • Acquired non-hemolytic jaundice

They can be caused by taking certain medications that pass in cells along the same path as indirect bilirubin, thereby displacing the pigment. In other words, enzymes are suppressed and bilirubin is accumulated. Such drugs include contraceptive, morphine-containing and others.

In a person with a well-functioning liver, only a significant excess of the prescribed dosages of the medication may be the reason why indirect bilirubin is elevated in the blood. If there is any syndrome of the above, even the prescribed standard medications significantly affect the concentration of indirect bilirubin in the blood.

  1. Gall bladder

Since bilirubin is a bile pigment, a significant part of it is contained in this organ. If the flow of bile from the bladder is disturbed, the direct and indirect bilirubin becomes elevated.

Other causes of bilirubin increase include infection with parasites( worms), lack of vitamin B12 in the body, and autoimmune diseases.

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Causes when indirect bilirubin is lowered

Lowered bilirubin is accompanied by low red blood cell levels. Indeed, as already mentioned, it is as a result of hemolysis( disintegration) of these blood cells that bile pigment is secreted.

Low concentration of indirect bilirubin in the blood is not so widely used in the diagnosis of diseases as high. However, indirect bilirubin may be reduced as a result of the presence of the following conditions in the body:

  • Renal failure;
  • Leukemia;
  • Tuberculosis;
  • Depletion of the body.

At the same time, reduced analysis rates may be a common error. In order for the quantitative ratio of direct and indirect bilirubin in the blood to correspond to the truth, it is necessary to pass the test in the morning, on an empty stomach, without emotional and physical overstrain before donating blood.

Leave comments if you have questions or additions on the topic of analysis of indirect bilirubin.

God bless you!