creation date: 2026-09-14 20:00
tags: Pathologies
Neonatal Hyperbilirubinemia
Background
Definitions
Neonatal hyperbilirubinemia, sometimes referred to as physiologic jaundice, is a common condition which is usually benign in term and late preterm newborns.
Approximately 10% of newborns have clinically significant elevations of total serum bilirubin levels requiring monitoring or treatment.
Normal Physiology
Benign neonatal hyperbilirubinemia occurs in nearly all newborns as a result of the turnover of fetal red blood cells and the immaturity of the newborn’s liver to effective metabolize the bilirubin, resulting in a buildup of unconjugated bilirubin.
The normal trajectory of TSB levels are:
- Peak TSB at 48-96 hours of age (may be delayed to 72-120 hours of age in East Asians), with 221 mcmol/L as the 90th percentile
- Resolution within 1-2 weeks after birth
Etiology & Pathophysiology
In majority of cases, jaundice is physiological.
In some cases, an underlying pathologic cause may result in significant neonatal hyperbilirubinemia that requires treatment. Note that jaundice <24 hours of life is always pathologic.
Increased production
This is the most common cause, which may be due to:
- Isoimmune-mediated hemolysis (eg. ABO or RhD incompatibility)
- Inherited RBC membrane defects
- Erythrocyte enzymatic defects
- Sepsis
- Polycythemia or sequestration of blood within a closed space (eg. cephalohematomas)
Decreased clearance
Inherited defects within the conjugation pathway reduces hepatic bilirubin clearance:
- Crigler-Najjar syndrome
- Gilbert syndrome
- OATP-2 polymorphism
- Metabolic disorders (congenital hypothyroidism, galactosemia, panhypopituitarism)
Increased enterohepatic circulation of bilirubin
- Breast milk jaundice
- Anatomic/ileus causes of intestinal obstruction
Risk Factors
Factors associated with severe hyperbilirubinemia include:
- Elevated predischarge bilirubin level
- Prematurity (increases with each week earlier than 40)
- Early-onset jaundice (within 24 hours of birth)
- Known or suspected hemolytic disease
- Family history of phototherapy or exchange transfusion
- Family history of inherited hemolytic disorder
- Cephalohematoma or other significant bruising from birth trauma
- Down syndrome
- Macrosomia
- Exclusive breastfeeding with suboptimal intake
Clinical Presentation
Signs & Symptoms
The only sign of hyperbilirubinemia may be jaundice.
History & Physical Exam
Screening
Bilirubin is a part of the newborn screen. This consist of:
- Maternal blood group (ABO and Rh) testing prior to delivery
- DAT with other signs of hemolysis
Diagnosis
Criteria
As generally all newborns will have some level of hyperbilirubinemia, the importance of a diagnosis consist in recognizing cases where follow-up or treatment is necessary.
The infant’s TSB should be compaired to a gestationage and infant age phototherapy threshold. A ΔTSB should be ≤30 mcmol/L should delay discharge or initiate phototherapy.
Work-up
Differential
Red Flags / Complications
The major complication of hyperbilirubinemia is neurotoxicity:
- Bilirubin-induced neurologic disorder (BIND)
- Disorders in visuocortical pathways
- Sensorineural hearing loss
- Abnormal proprioception
- Speech and language disabilities
- Processing disorders
- Cognitive delays
- Acute bilirubin encephalopathy
- Lethargy
- Mild to moderate hypotonia
- Late stage: seizures and coma
- Chronic bilirubin encephalopathy
- Choreoathetoid cerebral palsy
- Sensorineural hearing loss
- Gaze palsies
- Dental enamel hypoplasia
Management
Monitoring
In infants who’s TSB do not meet phototherapy thresholds but may be trending in a manner at which the plateau is not evident, follow up in outpatient clinic in 2-3 days is appropriate.
In infants where the plateau is evident, follow-up is unnecessary.
Interventional
For infants that meet phototherapy thresholds, referral to pediatrics for phototherapy should be initiated.