Hyperbilirubinemia is an increase in the content of bilirubin in the blood more than 20.5 µmol / l. Most often it is an indicator of an infectious or inflammatory pathology of the liver, biliary tract. Also, the cause may be metabolic disorders, hemolytic anemia, and other diseases of the digestive tract. The leading clinical sign is jaundice. The remaining symptoms are determined by the underlying disease. The level of bilirubin is examined in a biochemical blood test on an empty stomach. Treatment depends on the pathology against which hyperbilirubinemia has developed.
Hyperbilirubinemia (THD) is not an independent disease, but a laboratory syndrome that occurs in many nosological forms. Bilirubin is a yellow pigment that is formed from the hemoglobin of red blood cells that have undergone destruction by the reticuloendothelial system (spleen sinusoids). It is then metabolized by the liver and excreted in the bile. Its increase confirms the presence of true jaundice in the patient. Determination of the concentration of bilirubin fractions (unconjugated, conjugated) assists in establishing the origin of jaundice (suprahepatic, hepatic, subhepatic).
Hyperbilirubinemia almost always indicates pathology. However, there are exceptions. For example, the cause of hyperbilirubinemia can be prolonged starvation (deficiency of albumin, cellular carrier proteins), the use of drugs that cause competitive inhibition of bilirubin uptake by hepatocytes (radiocontrast agents, drugs for the treatment of helminthiases).
In newborns, the cause of hyperbilirubinemia is physiological jaundice, which develops due to the immaturity of the enzymatic systems of bilirubin metabolism. The causes of pathological hyperbilirubinemia are as follows (listed in order of frequency of development):
Features of the pathogenesis (mechanisms of occurrence) of hyperbilirubinemia are determined by the cause. Free (indirect, non-conjugated) bilirubin is poorly soluble in water, but it has a high lipophilicity, i.e. dissolves well in fats. Therefore, it can interact with phospholipids of cell membranes, especially brain cells, due to which it penetrates the blood-brain barrier, where it uncouples the processes of oxidative phosphorylation and reduces ATP synthesis.
This explains the toxicity of free bilirubin to the cells of the nervous system. This is most pronounced in newborns. Bilirubin is able to stain the skin, visible mucous membranes, urine, and feces in a characteristic yellow or dark brown color. With prolonged cholestasis, which causes an increase in the concentration of conjugated bilirubin, catabolism and cholesterol excretion may be disturbed, which leads to its accumulation in the blood, progression of atherosclerosis.
Depending on which fraction of the bile pigment is increased, there are:
Bilirubin encephalopathy (nuclear jaundice) stands out separately. It occurs in hemolytic disease of the newborn, the cause of which is the incompatibility of erythrocyte antigens (Rhesus conflict) of the mother and fetus. This disease is very severe, it is characterized by damage to the subcortical nuclei, the cerebral cortex and requires immediate treatment.
The accumulation of yellow pigment in the skin, mucous membranes, and biological fluids leads to a change in their color, which is the main symptom of hyperbilirubinemia. Yellowness of the sclera is the earliest sign, it occurs when the concentration of bilirubin exceeds the normal values by 2 times. The palate, the back of the tongue also begin to stain early. The skin turns yellow at levels above 80-85 µmol/L.
With different diseases, there is an unequal intensity of skin staining, its various shades. So, for example, with hemolytic anemia, the skin and mucous membranes have a faint lemon-yellow color, the feces become dark. In diseases of the liver, the skin becomes orange-yellow, and the urine becomes dark in color. In the pathology of the biliary tract, the bilirubin accumulating in the skin is oxidized to biliverdin, which gives it a bright green-yellow color, and the feces, on the contrary, become light (“acholic feces”) due to a violation of the outflow of bile. In the case of prolonged cholestasis, bilirubin in the skin begins to increase its pigmentation, due to which it becomes dark.
Other symptoms depend on the cause that caused hyperbilirubinemia. In patients with hemolytic anemia, fever is observed (due to the pyrogenic activity of free bilirubin), an enlarged spleen, an anemic syndrome - pale skin, increased heart rate, and a decrease in blood pressure. In diseases of the liver and gallbladder, patients are often worried about the severity or dull pain in the right hypochondrium, attacks of biliary colic, intolerable skin itching.
In patients with benign hyperbilirubinemia, the clinical picture is dominated by asthenovegetative syndrome (general weakness, drowsiness, impaired concentration). In adults, unlike newborns, despite the high concentration of bile pigment, encephalopathy does not develop.
The most frequent and dangerous complications are not associated with hyperbilirubinemia itself, but with the cause that caused it. Severe adverse effects of hyperbilirubinemia occur in newborns with kernicterus. Deep damage to the subcortical nuclei and the cerebral cortex without timely treatment can lead to sensorineural hearing loss, seizures, and in some cases, death. Due to the deterioration of cholesterol excretion into bile, its plasma concentration increases, as a result of which the process of atherosclerotic plaque formation is accelerated. This increases the risk of myocardial infarction, ischemic stroke.
The profile of a specialist who supervises a patient with hyperbilirubinemia is determined by the cause that caused it. Most often, such patients are treated by gastroenterologists, hematologists. When examining a patient, the skin, mucous membranes of the eyes, mouth are carefully examined, the abdomen is palpated for hepatosplenomegaly, symptoms of biliary tract lesions (Murphy, Ortner, Kera). To determine the cause of hyperbilirubinemia, an additional examination is prescribed, including:
The differential diagnosis of hyperbilirubinemia can be carried out according to its main clinical manifestation - jaundice. Icteric coloration of the skin is possible when eating a large amount of foods rich in carotene (carrots, pumpkins, avocados), taking certain medications (Akrikhin). The main distinguishing feature of "pseudo-jaundice" from the true one is that the sclera remain uncolored.
To normalize the indicators of bile pigment, it is necessary to fight the cause of hyperbilirubinemia. Depending on the patient's condition, he can be treated both on an outpatient basis and in a hospital. Most often, such patients are hospitalized in the gastroenterology department. The following treatments are used:
The main treatment for gallstone disease and calculous cholecystitis is the surgical removal of the gallbladder (laparoscopic cholecystectomy). In case of failure of conservative methods of treatment of hemolytic anemia, they resort to the removal of the spleen (splenectomy). Tumors of the pancreas or duodenum that cause compression of the ducts are also subject to surgical removal.
The prognosis and life expectancy in hyperbilirubinemia is determined by the cause, i.e. underlying disease. For example, hemolytic disease of the newborn, viral hepatitis B, C, some forms of hemolytic anemia (hemoglobinopathies) are characterized by a high rate of death. Benign hyperbilirubinemia, chronic cholecystitis, on the contrary, have a favorable prognosis, do not affect life expectancy in any way.
To prevent hyperbilirubinemia, you should limit the use of alcohol, fatty foods. Rh-negative pregnant women are given anti-Rhesus immunoglobulin (anti-D-immunoglobulin) to prevent the development of TTH.