Liver function Tests:- Part 4 – Neonatal Jaundice, Types and Diagnosis (LFT)

Liver function Tests

Neonatal Jaundice

Sample

1. The blood of the neonate is needed.
2. In difficult cases may get blood from the femoral vein.
3. Blood can be obtained from the finger or the heel prick.

Definition and importance of neonatal jaundice:

1. Neonatal jaundice appears in the early days of the newborn.
2. If jaundice persists beyond the 14 days, it indicates some pathological cause.
   1. This may be a hemolytic disease of the newborn that starts in utero and causes jaundice, anemia, and hepatosplenomegaly in mature infants.
   2. The degree of the severity of the disease ranges from mild anemia to mental retardation, brain damage, and kernicterus or stillbirth.
3. The early diagnosis and the significance of unconjugated hyperbilirubinemia is the potential for the development of Kernicterus.
4. Kernicterus causes neurotoxicity.
   1. There are lethargy and gradual progress in opisthotonus and seizures.
   2. 70% of the affected neonates die within the first week.
   3. The rest will have severe brain damage.
   4. This can be prevented by blood exchange transfusion and phototherapy.

Type of neonatal jaundice:

1. Physiologic jaundice.
2. Pathologic jaundice.
3. Neonatal jaundice may be:
   1. Unconjugated hyperbilirubinemia:
      1. Physiologic jaundice.
      2. Hemolytic disease.
      3. Breast milk hyperbilirubinemia.
   2. Conjugated hyperbilirubinemia:
      1. Idiopathic neonatal hepatitis.
      2. Biliary atresia.

Physiologic jaundice:

1. This is the benign type of jaundice.
2. This results from the insufficient hepatocyte enzyme and so unconjugated bilirubin is increased.
3. This jaundice appears in the first 2 to 3 days.
   1. If it goes to 10 to 12 mg/dL in the first day, then it is pathological jaundice.
4. Bilirubin rarely goes above 5 mg/dL per day.
   1. 90% is unconjugated.
5. The peak level is for 4 to 5 days and the level is around 5 to 6 mg/dL.
   1. This jaundice lasts for roughly 2 weeks.
6. This is treated by phototherapy (450 nm light source).
   1. Light converts bilirubin to a stable nontoxic isomer.

Pathologic jaundice:

1. The most common cause is the hemolytic disease of the newborn (HDN).
2. There is severe hyperbilirubinemia.
3. The blood-brain barrier is not well developed so unconjugated bilirubin can cross this barrier.
4. The damage to the brain is called Kernicterus.
5. In kernicterus, there is yellowness of the subthalamic nucleus, hippocampus, thalamus, putamen, cerebellar nuclei, cranial nerves, and globus pallidus.
6. Differentiating points from physiologic jaundice are:
   1. The appearance of jaundice within the first 24 hours of birth.
   2. The persistent rise in the bilirubin beyond one week.
   3. Persistent jaundice beyond 10 days.
   4. Bilirubin level exceeding 12 mg/dL.
   5. If there is a single day rise of 5 mg/dL.
   6. Conjugated bilirubin may exceed 2 mg/dL.
      

      Mechanism of Neonatal jaundice

Differential diagnosis of neonatal jaundice:

1. Jaundice appearing in the first 24 hours suggest:
   1. Hemolytic disease of the newborn, Erythroblastosis fetalis.
   2. Sepsis.
   3. Concealed hemorrhage.
   4. TORCH infection.
2. Jaundice appearing between 3 to 7 days of birth suggests:
   1. Bacterial infections like urinary tract,
3. Jaundice appearing after one week of birth suggests:
   1. Bacterial sepsis.
   2. Extrahepatic biliary atresia.
   3. Cystic fibrosis.
   4. Breast milk jaundice.
   5. Congenital absence of bile duct.
   6. Neonatal hepatitis. galactosemia.
   7. Hemolytic anemia is like a G6PD deficiency, hereditary spherocytosis.

Treatment

1. Phototherapy may be considered when the bilirubin level is:
   1. above 10 mg/dL before 12 hours of birth.
   2. above 12 mg/dL before  18 hours of birth.
   3. Above 14 mg/dL before 24 hours of birth.
   4. Phototherapy converts unconjugated bilirubin into a molecule that can be excreted without conjugation.
   5. Phototherapy is not good for conjugated hyperbilirubinemia.
2. Blood exchange transfusion is considered when the bilirubin level exceeds 20 mg/dL.

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