Physiological jaundice, also known as neonatal jaundice, affects more than half of full-term babies and almost all premature babies.
This condition is caused by disturbances in metabolism bilirubin. There are significantly more red blood cells (erythrocytes) in the blood of a developing baby in the womb than a baby. This is because the fetus does not breathe on its own, but receives oxygen from the mother’s blood through the placenta. This mechanism requires much more efficient transport than oxygen obtained from gas exchange in the lungs – as it does in the extrauterine life.
After birth, the “supernumerary” red blood cells become redundant and break down. A yellow dye is formed as a by-product – bilirubin. With fully efficient physiological mechanisms, bilirubin goes to the liver, where it undergoes biochemical changes and is excreted into the intestines as a bile component.
However, not every newborn baby (especially a premature baby) has the liver developed sufficiently to absorb and process significant amounts of bilirubin. Therefore, the excess of this dye circulates in the blood and is deposited in the tissues, which manifests itself in yellowing of the skin and visible mucous membranes, i.e. jaundice.
The criteria for determining whether a newborn has physiological – not pathological – jaundice is when the yellow color appears and disappears. In full-term babies, physiological jaundice:
• appears in the second day of life
• peaks at 4-5. day
• gradually disappears by the 10th day of life.
Physiological jaundice of premature babies usually appears on the third day of life and may persist up to the 3st day after birth.
An additional criterion that distinguishes physiological from pathological jaundice is the level of bilirubin in the blood serum. It should not exceed:
in full-term newborns – 205 micromoles per liter (12 mg / dl)
in premature babies – 257 micromoles per liter (15 mg / dl).
Usually, however, this parameter is not determined and is limited to visual assessment of the yellowness of the tissues.
Characteristic for physiological jaundice is the sequence in which it affects individual areas of the body. Yellowness appears successively on:
• face
• the torso
• limbs
• hands and feet.
The order in which jaundice resolves is exactly the opposite.
As a physiological condition, neonatal jaundice does not require treatment. It is also worth remembering that in some children the yellowing of the skin is very small – even imperceptible. This is not a cause for concern as it is a sign that the liver is functioning properly.
In addition to the physiological jaundice of newborns, it also appears pathological jaundice. It develops earlier, lasts longer, and is accompanied by elevated bilirubin levels. Unlike physiological jaundice, this condition requires treatment.
Read also: Jaundice
Text: SzB
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