Liver function Tests:- Part 4 – Neonatal Jaundice, Types and Diagnosis (LFT)
Liver function Tests
Neonatal Jaundice
Sample
- The blood of the neonate is needed.
- In difficult cases may get blood from the femoral vein.
- Blood can be obtained from the finger or the heel prick.
Definition and importance of neonatal jaundice:
- Neonatal jaundice appears in the early days of the newborn.
- If jaundice persists beyond the 14 days, it indicates some pathological cause.
- This may be a hemolytic disease of the newborn that starts in utero and causes jaundice, anemia, and hepatosplenomegaly in mature infants.
- The degree of the severity of the disease ranges from mild anemia to mental retardation, brain damage, and kernicterus or stillbirth.
- The early diagnosis and the significance of unconjugated hyperbilirubinemia is the potential for the development of Kernicterus.
- Kernicterus causes neurotoxicity.
- There are lethargy and gradual progress in opisthotonus and seizures.
- 70% of the affected neonates die within the first week.
- The rest will have severe brain damage.
- This can be prevented by blood exchange transfusion and phototherapy.
Type of neonatal jaundice:
- Physiologic jaundice.
- Pathologic jaundice.
- Neonatal jaundice may be:
- Unconjugated hyperbilirubinemia:
- Physiologic jaundice.
- Hemolytic disease.
- Breast milk hyperbilirubinemia.
- Conjugated hyperbilirubinemia:
- Idiopathic neonatal hepatitis.
- Biliary atresia.
- Unconjugated hyperbilirubinemia:
Physiologic jaundice:
- This is the benign type of jaundice.
- This results from the insufficient hepatocyte enzyme and so unconjugated bilirubin is increased.
- This jaundice appears in the first 2 to 3 days.
- If it goes to 10 to 12 mg/dL in the first day, then it is pathological jaundice.
- Bilirubin rarely goes above 5 mg/dL per day.
- 90% is unconjugated.
- The peak level is for 4 to 5 days and the level is around 5 to 6 mg/dL.
- This jaundice lasts for roughly 2 weeks.
- This is treated by phototherapy (450 nm light source).
- Light converts bilirubin to a stable nontoxic isomer.
Pathologic jaundice:
- The most common cause is the hemolytic disease of the newborn (HDN).
- There is severe hyperbilirubinemia.
- The blood-brain barrier is not well developed so unconjugated bilirubin can cross this barrier.
- The damage to the brain is called Kernicterus.
- In kernicterus, there is yellowness of the subthalamic nucleus, hippocampus, thalamus, putamen, cerebellar nuclei, cranial nerves, and globus pallidus.
- Differentiating points from physiologic jaundice are:
- The appearance of jaundice within the first 24 hours of birth.
- The persistent rise in the bilirubin beyond one week.
- Persistent jaundice beyond 10 days.
- Bilirubin level exceeding 12 mg/dL.
- If there is a single day rise of 5 mg/dL.
- Conjugated bilirubin may exceed 2 mg/dL.
Differential diagnosis of neonatal jaundice:
- Jaundice appearing in the first 24 hours suggest:
- Hemolytic disease of the newborn, Erythroblastosis fetalis.
- Sepsis.
- Concealed hemorrhage.
- TORCH infection.
- Jaundice appearing between 3 to 7 days of birth suggests:
- Bacterial infections like urinary tract,
- Jaundice appearing after one week of birth suggests:
- Bacterial sepsis.
- Extrahepatic biliary atresia.
- Cystic fibrosis.
- Breast milk jaundice.
- Congenital absence of bile duct.
- Neonatal hepatitis. galactosemia.
- Hemolytic anemia is like a G6PD deficiency, hereditary spherocytosis.
Treatment
- Phototherapy may be considered when the bilirubin level is:
- above 10 mg/dL before 12 hours of birth.
- above 12 mg/dL before 18 hours of birth.
- Above 14 mg/dL before 24 hours of birth.
- Phototherapy converts unconjugated bilirubin into a molecule that can be excreted without conjugation.
- Phototherapy is not good for conjugated hyperbilirubinemia.
- Blood exchange transfusion is considered when the bilirubin level exceeds 20 mg/dL.