Synonym
neonatal jaundice, neonatal hyperbilirubinemia : jaundice
Definition and word origin
A neonatal icterus represents the increased concentration of bilirubin, a breakdown product of the blood pigment haemoglobin, in the blood of the newborn. Jaundice occurs in more than half of all healthy newborns, and a bilirubin concentration of up to 15 mg/dl in serum is considered physiological and harmless. If the bilirubin concentration of 20 mg/dl in the serum is exceeded, this is called severe jaundice. The term jaundice is derived from the yellow color of bilirubin, which, when highly elevated in the blood, can stain the skin and sclera of the eye yellow. Icterus prolongatus is a special form of neonatal jaundice: This icterus lasts longer than two weeks and requires close medical supervision of the affected child.
Causes and development of newborn jaundice
In the womb, the oxygen supply of the fetus is achieved by the diffusion of oxygen between maternal and fetal vessels of the placenta. Since the oxygen content of the infant’s blood remains relatively low, an increased proportion of the red blood pigment haemoglobin develops in the child to optimize oxygen transport. After birth, the child has sufficient oxygen available and at the same time the fetal hemoglobin is exchanged for adult hemoglobin.
This results in increased hemoglobin breakdown in the first days of life, which the still immature liver cannot adequately handle. This results in an increased concentration of the hemoglobin breakdown product bilirubin in the child’s blood. Certain factors, which are mainly associated with an increased breakdown of red blood cells, increase the risk of the child developing neonatal jaundice.
Premature babies and sick children are particularly at risk. The presence of a bile duct obstruction (bile duct atresia) can also prevent the excretion of bilirubin and should therefore be clarified. If the discharge of the first bowel movement (meconium) is delayed, split bilirubin can be increasingly reabsorbed from the intestine and increase jaundice.
- Reduced level of the “bilirubin transporter” albumin in the blood
- Hypoglycemia or blood poisoning
- Lack of oxygen or shock
- Blood group incompatibility between mother and child
- Hemolytic diseases
- Large haematomas (bruises)
- Early onset of jaundice within 24 hours after birth
- Jaundice in a sibling
In neonatal icterus, indirect bilirubin is elevated because the liver cannot convert it into direct bilirubin quickly enough. The indirect bilirubin is therefore elevated compared to that of adults, the direct bilirubin corresponds to the values of adults. However, due to the increased indirect bilirubin, the total bilirubin is also increased.
Accordingly, the total bilirubin concentration is checked in laboratory tests. The limit value on the first day of life is 8.7mg/dl, everything below this is normal. Normal values in 4-6 day old children are between 0.1-12.6 mg/dl.
If the value increases, the typical symptoms appear. Icterus gravis, i.e. severe jaundice, is seen in mature newborns with values above 20 mg/dl. If the newborn is still immature, severe jaundice can occur from values as low as 10 mg/dl. Early jaundice (Icterus praecox) is present if the newborn develops jaundice on the first day of life. In this case, the bilirubin rises to values above 12 mg/dl in the first 36 hours after birth.
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