Neonatal Jaundice and its cause

Neonatal Jaundice

 Neonatal jaundice or neonatal hyper- bilirubinemia is a common condition. Chemical hyperbilirubinemia (Serum bilirubin >2 mg%) is almost universal.

Neonatal Jaundice

In an adult, scleral icterus is visible if the bilirubin more than 2 mg%, where- as in a newborn baby icterus is visible only when the bilirubin is more than 5.7 mg%. This visible icterus or clinical hyperbilirubinemia is seen for some time and to a variable degree in almost 65% of full term and 80% of preterm ba- bies.

Exaggerated hyperbilirubinemia (Serum bilirubin >13 mg%) is seen in a small fraction of cases and depends on certain predisposing factors which will be discussed later. Serum bilirubin >20 mg% could be dangerous with a risk of kernicterus and may be seen in up to 1-2% of cases of jaundice.

PHYSIOLOGICAL HYPERBILIRU- BINEMIA

Most of the cases of neonatal hyper- bilirubinemia has the following char- acteristics:

1. . It appears after 24 hours of birth.
2.   It reaches its peak by 3rd or 4th day.
3.  The peak level is less than 12-13 mg%.
4.   It disappears by 8 days.
5.  The direct bilirubin fraction is < 1.5 mg%.
6.  The baby is clinically well, active and feeding properly.

All the above criteria have to be satisfied to call it physiological hyperbili rubinemia .

 Normal Bilirubin Metabolism 

The bilirubin is produced from break down of hemoglobin . This is measured as the indirect bilirubin. This is taken up from plasma by hepatocytes with the help of Y and Z proteins and con jugated by UDPG- T enzyme to form the conjugated or direct bilirubin which is excreted in the intestines .

Here it is converted by bacteria in the gut to stercobilin which is excreted in stools .

 Pathogenesis of Physiological Hy perbilirubinemia:

 

Factors Exaggerating Physiological Hyperbilirubinemia:

Non – physiological Hyperbilirubin emia