Neonatal Unconjugated Hyperbilirubinemia

Pathophysiological Mechanisms

The American Academy of Pediatrics recommends that unconjugated hyperbilirubinemia occurs when insoluble bilirubin cannot be converted efficiently into soluble conjugated bilirubin by the liver, which can be physiological or pathological depending on intensity and duration 1, 2, 3

The European Society for Pediatric Gastroenterology, Hepatology and Nutrition notes that an increase in total unconjugated bilirubin during the neonatal period is the most frequent cause, occurring in 60% of term newborns and 80% of preterm infants, and may become pathological if elevated or prolonged 1, 2
The American Academy of Pediatrics states that ABO and Rh(D) incompatibility can cause immune hemolysis with increased red blood cell destruction 4
The American Academy of Pediatrics recommends that glucose-6-phosphate dehydrogenase (G6PD) deficiency can cause a sudden increase in bilirubin and requires intervention at lower thresholds 5
The American Academy of Pediatrics notes that insufficient breast milk intake and dehydration associated with insufficient breastfeeding contribute to the development of hyperbilirubinemia 6

The American College of Obstetricians and Gynecologists recommends screening for maternal ABO and Rh(D) blood group with testing for irregular antibodies in all pregnant women 4
The American Academy of Pediatrics recommends direct Coombs test, blood group, and Rh(D) testing on cord blood if the mother is Rh-negative or untyped 4
The American Academy of Pediatrics states that evaluation of jaundice every 8-12 hours by blanching the skin with digital pressure is necessary 4
The American Academy of Pediatrics recommends measuring transcutaneous bilirubin (TcB) or total serum bilirubin (TSB) for any jaundice appearing in the first 24 hours of life 4

The American Academy of Pediatrics recommends an algorithmic approach to diagnosis, including immediate measurement of TSB/TcB for jaundice in the first 24 hours, testing for hemolysis, and evaluating breastfeeding and dehydration 4, 5, 6
The American Academy of Pediatrics notes that if hemolysis is absent, evaluation of breastfeeding, dehydration, and enzymatic deficiency should be considered 5, 6
The American Academy of Pediatrics recommends that if jaundice is excessive or progressing rapidly, underlying causes including urinary tract infection should be investigated 4
The American Academy of Pediatrics states that for persistent jaundice >2-3 weeks, conjugated bilirubin should be measured, and thyroid function and galactosemia should be evaluated 4

The American Academy of Pediatrics classifies gestational age 35-36 weeks as a major risk factor for severe hyperbilirubinemia requiring lower treatment thresholds 7

Treatment thresholds for phototherapy are lower in preterm infants due to increased risk of bilirubin neurotoxicity, as recommended by the American Academy of Pediatrics 8, 9
The combination of prematurity with breastfeeding difficulties creates compounded risk for prolonged jaundice, according to the American Academy of Pediatrics 7

The American Academy of Pediatrics recommends systematic risk assessment before discharge, particularly for premature infants discharged before 72 hours of age 7
Pre-discharge bilirubin measurement is essential, with plotting of TSB or TcB on hour-specific nomograms to determine risk zone, as suggested by the American Academy of Pediatrics 10, 7
Mandatory follow-up is required for infants 35-36 weeks gestation, with follow-up within 24-48 hours of discharge, as recommended by the American Academy of Pediatrics 7
Lower phototherapy thresholds are recommended, with intervention occurring at lower TSB levels in younger gestational ages to prevent further increases, according to the American Academy of Pediatrics 8, 9

The American Academy of Pediatrics advises against visual estimation of jaundice, recommending measurement of TSB or TcB instead, especially in premature infants 10
Underlying hemolysis, such as G6PD deficiency, should be considered and tested for in preterm infants with severe jaundice, as recommended by the American Academy of Pediatrics 7