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Emergency and Acute Medicine – Neonatal Jaundice
Neonatal jaundice results from an imbalance between bilirubin production and elimination. Newborns produce bilirubin at a higher rate than adults because of increased red blood cell mass and a shorter red blood cell lifespan. At the same time, especially in preterm infants, hepatic conjugation and biliary excretion of bilirubin are immature. Increased enterohepatic circulation and reduced bilirubin binding to albumin further contribute to elevated bilirubin levels. In most newborns, this process leads to physiologic jaundice, which is benign and self-limited.
In physiologic jaundice, bilirubin levels typically rise from approximately 1.5 mg/dL in cord blood to a mean peak of about 6.5 mg/dL by the third day of life, then gradually decline to less than 1.5 mg/dL by 10–12 days of age. However, when bilirubin levels rise excessively or rapidly, they may overwhelm neuroprotective mechanisms. Unbound bilirubin can cross the blood–brain barrier and deposit in the basal ganglia, hippocampus, brainstem nuclei, and cerebellum, leading to bilirubin-induced neurologic dysfunction (BIND). This spectrum ranges from mild neurologic dysfunction to acute bilirubin encephalopathy (ABE) in the first week of life, and to kernicterus, the chronic and often devastating form associated with permanent neurologic sequelae such as choreoathetoid cerebral palsy, gaze abnormalities, hearing loss, and dental dysplasia. Severe cases may result in coma, seizures, respiratory failure, and death.
The progression and severity of bilirubin neurotoxicity depend on multiple factors, including the rate and duration of bilirubin elevation, albumin-binding capacity, levels of unbound bilirubin, host susceptibility, and the presence of comorbidities. Risk factors for severe hyperbilirubinemia include jaundice in the first 24 hours of life, high predischarge total serum bilirubin (TSB) or transcutaneous bilirubin (TcB) levels, lower gestational age (35–38 weeks), exclusive breastfeeding with inadequate intake and excessive weight loss, hemolytic disease, a family history of neonatal jaundice, cephalohematoma or significant bruising, and East Asian ethnicity. Neurotoxicity risk is further increased by isoimmune hemolytic disease, G6PD deficiency, asphyxia, sepsis, acidosis, low albumin levels, and post-phototherapy bilirubin rebound.
Etiologies of neonatal jaundice are broadly divided into unconjugated and conjugated hyperbilirubinemia. Unconjugated causes include physiologic jaundice, breastfeeding failure jaundice due to inadequate milk intake in the first week of life, and breast milk jaundice, which typically begins after day 3–5 and may persist for several weeks. Hemolytic causes include ABO or Rh incompatibility, red cell enzyme deficiencies such as G6PD deficiency, and membrane disorders like hereditary spherocytosis. Other contributors include sepsis, birth trauma with increased heme load, polycythemia, infants of diabetic mothers, congenital hypothyroidism, and inherited defects of bilirubin conjugation such as Gilbert syndrome or Crigler–Najjar syndrome. Conjugated hyperbilirubinemia reflects impaired excretion and is always pathologic, with causes including neonatal hepatitis, biliary atresia, extrahepatic obstruction, shock liver, and neonatal hemosiderosis.
Clinically, affected infants may present with sleepiness, poor feeding, decreased urine output, or signs of dehydration. Early ABE is characterized by feeding difficulties, hypotonia, irritability, and lethargy. Intermediate stages include a high-pitched cry, fever, and increased tone with retrocollis and opisthotonos. Advanced ABE presents with severe hypertonia, seizures, coma, and abnormal movements. On examination, jaundice manifests as yellow discoloration of the skin and sclera, progressing in a cephalocaudal pattern as bilirubin levels rise. Visual assessment alone is unreliable, particularly in infants with darker skin tones. Neurologic abnormalities such as altered tone and the “setting sun” sign should raise concern for neurotoxicity.
Evaluation requires prompt measurement of total serum bilirubin in any infant with suspected or visible jaundice. The initial bilirubin level must be fractionated into unconjugated and conjugated components. TSB values must always be interpreted according to the infant’s age in hours, not days, and plotted on an age-specific nomogram to assess risk and guide treatment decisions. TcB measurements correlate well with TSB when available. Further evaluation is warranted when jaundice appears in the first 24 hours, persists beyond the first week, reaches phototherapy thresholds, involves elevated conjugated bilirubin, or is associated with signs of ABE. Additional laboratory studies may include serum albumin, electrolytes, renal function, complete blood count, reticulocyte count, blood type, direct Coombs test, and sepsis evaluation when indicated.
Management is time-sensitive, as outcomes are closely linked to the duration and severity of bilirubin exposure. Infants with signs of encephalopathy require immediate treatment. Phototherapy should be initiated when TSB exceeds threshold levels based on age in hours and risk stratification. Intensive phototherapy involves high irradiance delivered to as much of the infant’s surface area as possible, with eye protection in place, and should result in a bilirubin decline of more than 0.5 mg/dL per hour. Exchange transfusion is indicated for infants who meet age-specific thresholds, fail to respond to intensive phototherapy, or exhibit signs of ABE, and requires neonatal intensive care support. Intravenous immunoglobulin may be considered in isoimmune hemolytic disease when bilirubin levels approach exchange thresholds.
Supportive care includes ensuring adequate hydration, correcting dehydration with intravenous fluids when necessary, and optimizing feeding. Breastfeeding should generally continue, with increased feeding frequency and supplementation as needed. Temporary cessation of breastfeeding may be considered in refractory breast milk jaundice, with maternal milk expression encouraged to maintain lactation. Underlying conditions such as sepsis, hypothyroidism, or polycythemia must be identified and treated promptly.
Hospital admission is required for infants needing intensive phototherapy, exchange transfusion, or evaluation of significant anemia, infection, dehydration, or suspected obstructive liver disease. Stable term infants with uncomplicated hyperbilirubinemia below treatment thresholds may be managed with close outpatient follow-up or home phototherapy when appropriate. Clear communication with primary care providers and timely follow-up—often within 8–12 hours—is essential to prevent progression to severe hyperbilirubinemia.
A key principle in the emergency setting is that bilirubin levels must always be interpreted in the context of postnatal age in hours and individual risk factors. Early recognition, prompt initiation of phototherapy when indicated, and careful assessment of feeding and hydration are critical to preventing irreversible neurologic injury.
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