Jaundice of newborns: insidious bilirubin

Jaundice of newborns: insidious bilirubin 0

Health & Care

Jaundice of newborns: insidious bilirubin

Of course, almost all parents are very concerned about the appearance of jaundice in their newborn baby. Is this process normal? Is it worth it to be afraid and should any action be taken?

Dorofey Apaeva Pediatrician, Scientific Center for Children's Health, Russian Academy of Medical Sciences, Moscow

About jaundice probably heard everything, but not everyone of us represents what kind of disease. Jaundice is called staining of the skin, visible mucous membranes and eye sclera in yellow. This is a consequence and a visible manifestation of a rise in the blood level of bilirubin. Bilirubin - a substance formed in the body during the decay of red blood cells - erythrocytes, to be more precise - contained in them hemoglobin. The aged and aged red blood cells are destroyed mainly in the spleen, while bilirubin is formed, called indirect, or unbound. It is insoluble in water (therefore, can not be excreted by the kidneys) and therefore for transport in the bloodstream is associated with albumin, a low-molecular protein of blood plasma. But most importantly - indirect bilirubin is a tissue poison, most of all it is dangerous for the central nervous system, in particular, the brain. Being bound to albumin, it reaches the liver, where its transformation takes place: it binds to the remainder of glucuronic acid and turns into direct (bound) bilirubin. In this new condition, it is non-toxic to the cells and tissues of the body, soluble in water and can be secreted by the kidneys. It also excretes with bile and enters the intestine. In cases where the rate of disintegration of red blood cells outstrips the binding capacity of the liver, indirect bilirubin begins to accumulate in the bloodstream and causes the skin, mucous membranes and eye sclera to yellow in color. 

Jaundice of newborns develops when the level of bilirubin in the blood exceeds 35-50 μmol / l in term infants and 85 μmol / l in premature babies. The severity of jaundice of newborns is determined not only by the concentration of bilirubin in the blood, but also by the features of the skin (the original color, the depth of the bedding and the tone of the capillaries, etc.) and therefore is not an objective indicator of the level of bilirubin. The eye sclera, the lower surface of the tongue, the palate, the skin of the face are most easily stained. 

In children of the first month of life, various kinds of jaundice can occur: conjugation (that is, associated with a low binding ability of the liver), hemolytic (due to increased destruction of erythrocytes - hemolysis), parenchymal (associated with toxic or infectious damage to liver cells) and obturation mechanical blockage of bile outflow). 

Let us dwell on each type of jaundice in more detail.

Conjugation jaundice

Physiological (transitory) jaundice - this state rightly refers to the so-called borderline states of newborns (this group includes conditions that are normal in most newborns, but require close monitoring, since in unfavorable events many characteristics of the body's functions can go beyond normal). 

Attention! Transient jaundice occurs in 60-70% of all newborns. 

By its nature, this type of jaundice is related to conjugation. This process is based on the restructuring of the hemoglobin system, which takes place after the birth of the baby. The fact is that the fetal hemoglobin differs from that of an adult: during fetal development, hemoglobin F (HbF) prevails in the body (it binds oxygen better), in comparison with the "usual", adult hemoglobin A (HbA), due to which and there is a transition of oxygen from the parent erythrocytes to the erythrocytes of the fetus. Shortly after the appearance of the baby, his body begins to rapidly destroy HbF in order to synthesize HbA. Naturally, the process of decomposition of hemoglobin leads to the formation of indirect bilirubin. Since the binding ability of the liver at this age is low, the concentration of bilirubin in the blood begins to gradually increase. Usually the first manifestations of physiological jaundice can be observed at the end of the 2nd, and more often on the 3-4th day of life. The intensity of the yellow color may increase slightly until the 5th-6th day. As a rule, the process has a benign course and everything ends well: by the end of the 1st week of life, the activity of liver enzymes is increasing, the level of bilirubin begins to decrease gradually until it reaches the norm, and by the end of week 2 the symptoms of jaundice are disappearing. But if there are "aggravating circumstances" (prematurity, immaturity of the fetus, hypoxia and / or asphyxia transferred, hereditary defects of the liver enzyme systems, use of certain drugs that displace bilirubin from the connection with glucuronic acid - for example, vitamin K, non-steroidal anti-inflammatory drugs, sulfonamides , levomitsetina, cephalosporins, oxytocin, newborn and mother), the level of bilirubin in the blood can rise to dangerous numbers. In this case, jaundice from the physiological state becomes a threatening state. Accordingly, jaundice of prematurity is distinguished, drug jaundice, jaundice of children with asphyxiation, etc.

Bilirubin on a critical level

In term infants, the critical level of bilirubin in the blood is 324 μmol / l, in premature infants - 150-250 μmol / l. This difference is due to the fact that preterm infants have increased blood-brain barrier permeability (a natural chemical-biological barrier between the lumen of the blood vessels and the brain tissue, through which many of the substances present in the blood plasma do not penetrate the brain cells), and immature cells of the brain are more sensitive to any kind of adverse effects. Toxic damage to the subcortical nuclei of the brain by indirect bilirubin is called nuclear jaundice, or bilirubin encephalopathy. Its symptoms are marked drowsiness or, on the contrary, a shrill scream, convulsions, a decrease in the sucking reflex, sometimes rigidity (tension) of the occipital muscles. 

That's why doctors at maternity homes closely monitor the level of bilirubin in the blood of all newborns. When jaundice occurs, newborns should prescribe this analysis 2-3 times during their stay in the hospital to determine if there is an increase in the concentration of bilirubin. Mom may wonder if the child took such tests. 

For the treatment of hyperbilirubinemia (increasing the level of bilirubin in the blood), intravenous transfusions of a 5% solution of glucose (it is a precursor of glucuronic acid binding bilirubin in the liver), ascorbic acid and phenobarbital (these drugs increase the activity of liver enzymes), cholagogue ( they accelerate the excretion of bilirubin with bile), adsorbents (agar-agar, cholestyramine) that bind bilirubin in the intestine and prevent it from being reabsorbed. However, today more and more researchers prefer phototherapy as the most physiological and effective method. When carrying out phototherapy, the baby's skin is irradiated with special lamps. When exposed to light of a certain wavelength, bilirubin passes into its photoisomer (it is called lumirubin), which is devoid of toxic properties and is readily soluble in water, so that without preliminary transformation in the liver it is excreted in the urine and bile. Procedures, as a rule, are conducted in the maternity hospital. Indication for the appointment of phototherapy is the concentration of bilirubin in the blood above 250 μmol / l for full-term newborns and above 85-200 μmol / l for premature infants (depending on the weight of the baby). 

To the conjugation group, jaundice also belongs to newborns breastfed with breast milk (Aries syndrome). Until now, the cause of the development of this state remains poorly understood. Perhaps in this "blame" the mother's estrogens (female sex hormones) present in the milk, since they can displace bilirubin from the bond with glucuronic acid. Perhaps the fact is that the sum of all the calories received per day with unsteady lactation will be lower than when fed with a mixture (it is known that with relative malnutrition, bilirubin can be reabsorbed in the intestine and re-enter the bloodstream). However, in the first week of life, the development of transient jaundice is noted 3 times more often in infants fed by breast milk (including donor milk) than in their peers transferred for one reason or another to artificial feeding. But to be frightened of this statistics it is not necessary: ​​it is proved, that early application to a breast and the subsequent 8-time feeding as a whole reduce frequency of development and degree of a hyperbilirubinemia at newborns. The diagnostic criterion for this type of jaundice will be a decrease in the level of bilirubin by 85 μmol / l or more with the termination of breast-feeding for 48-72 hours. More often for this test the child is not transferred to artificial nutrition even for these two or three days, it is enough to offer him expressed milk, preheated to a temperature of 55-60ºС and cooled to body temperature - 36-37ºС. With this treatment, the biological activity of estrogens and other substances of mother's milk that can compete for liver enzymes is significantly reduced. This sample is sometimes used to exclude other possible causes of jaundice. The course of this condition is benign, cases of bilirubin encephalopathy in the background of Aries syndrome are not described, therefore, treatment is usually not required, and children may well be breast-fed. 

Hemolytic jaundice

Такая желтуха возникает при повышенном гемолизе (распаде эритроцитов). Она может быть одним из проявлений гемолитической болезни новорожденных (ГБН), развивающейся у резус-положительных детей при резус-отрицательной крови матери. В таких случаях в организме матери могут вырабатываться антитела против эритроцитов плода, которые и разрушают их. В клинической картине гемолитической болезни – анемия (снижение уровня гемоглобина и эритроцитов), гипербилирубинемия, увеличение печени и селезенки, в тяжелых случаях – отечность тканей, скопление жидкости в полостях тела, резкое снижение мышечного тонуса, угнетение рефлексов. Hemolytic jaundice чаще всего появляется сразу после рождения или в первые сутки жизни, уровень билирубина быстро нарастает до угрожающих цифр. Для лечения ГБН чаще всего применяют оперативные методы. К ним прежде всего относится заменное переливание крови (ЗПК), иногда также применяется гемосорбция. При ЗПК у новорожденного забирается кровь, содержащая повышенный уровень билирубина и сниженное количество форменных элементов (клеток) крови, а ему переливается кровь донора. За одну процедуру производят замену до 70% объема крови. Таким образом, удается снизить концентрацию билирубина и предотвратить поражение головного мозга, а также восстановить необходимое количество эритроцитов, переносящих кислород. Нередко требуется повторное проведение процедуры, если уровень билирубина вновь начинает достигать критических цифр. Гемосорбция представляет собой очистку крови от билирубина, материнских антител и некоторых других веществ путем осаждения их в специальной установке. При нетяжелом течении ГБН могут применяться методы лечения, использующиеся при транзиторной желтухе.

In addition, hemolytic jaundice can develop with hereditary diseases, accompanied by defects in the structure of membranes or enzymes of erythrocytes or hemoglobin molecules. Any of these causes lead to increased destruction of erythrocytes and, as a result, to an increase in the level of bilirubin. Jaundice is noted from the first days of life. Concomitant symptoms are anemia, an enlarged spleen. The diagnosis is based on a combination of symptoms and a general analysis of blood, sometimes more research is needed. 

Parenchymal Jaundice 

Parenchymal Jaundice развивается при поражении клеток печени инфекционными или токсическими агентами, что приводит к снижению их способности связывать билирубин. На первом месте в этом ряду стоят внутриутробные инфекции: цитомегаловирус (он является причиной примерно 60% всех случаев затяжной желтухи у грудничков), токсоплазмоз, листериоз, краснуха, вирусные гепатиты. Как правило, мысль о внутриутробной инфекции возникает при развитии затяжной желтухи (когда ее продолжительность превышает 2–3 недели у доношенных новорожденных и 4–5 недель у малышей, родившихся недоношенными), а также при наличии других симптомов (увеличение печени, селезенки и периферических лимфоузлов, анемия (снижение уровня гемоглобина в крови), потемнение мочи и обесцвечивание кала, признаки воспаления в общем анализе крови (увеличение количества лейкоцитов, повышение СОЭ), повышение уровня печеночных ферментов в биохимическом анализе крови). Для постановки диагноза используют серологические реакции (обнаружение в крови антител к вирусам или бактериям), обнаружение РНК или ДНК возбудителя методом ПЦР (полимеразная цепная реакция – метод, позволяющий «воссоздать» ДНК или РНК по маленьким фрагментам, которые обнаруживаются в биологических жидкостях или тканях организма. После этого полученную РНК или ДНК исследуют на видопринадлежность (т.е. определяют вид возбудителя). 

Obturation jaundice

This condition occurs in connection with gross violations of the outflow of bile, obstruction (blockage) of the biliary tract. This jaundice develops in the developmental defects of the bile ducts (atresia, aplasia), intrahepatic hypoplasia, intra-uterine cholelithiasis, compression of the bile ducts, bile duct thickening syndromes, etc. A characteristic sign of obstructive jaundice is a yellowish-greenish skin tone, enlargement and compaction of the liver, periodic discoloration of stool. Jaundice appears on the 2-3 nd week of life. For diagnosis, X-ray methods and biopsies are used (examination of a piece of tissue under a microscope, and also using various biochemical methods). Treatment is most often surgical.

In this article, we tried to talk about some of the most common causes of jaundice in newborns. We hope that it will allow you to avoid unnecessary disturbances, and in cases where your fears are not unfounded, you can quickly orient yourself and show the kid to the specialist in time.