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An infant's direct (conjugated) serum bilirubin level is 3 mg/dL. The guidelines from the North American Society for Pediatric Gastroenterology, Hepatology, and Nutrition use the following definition for abnormal direct bilirubin: direct bilirubin is >1 mg/dL if total bilirubin is <5 mg/dL, or direct bilirubin is >20% of the total if the total bilirubin is >5 mg/dL. Conjugated hyperbilirubinemia is never normal or physiologic. It occurs in 1 in every 2500 infants. A persistent or increasing elevated direct bilirubin is always pathologic and must be evaluated promptly. Early diagnosis is urgent and treatment is essential because it means a better outcome for the infant and can be potentially lifesaving (eg, biliary atresia). The goal is to complete the evaluation by 45 to 60 days of age (surgery for biliary atresia has its best outcome if performed before the age of 45–60 days).
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II. IMMEDIATE QUESTIONS
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Is the urine dark, and what color is the stool? It is best to examine the stools because history obtained by someone else may not be accurate. Dark urine is a nonspecific indicator of increased conjugated bilirubin. Persistent pale or clay-colored stools occur with cholestasis and obstruction needs to be ruled out. One or two pale stools usually do not indicate disease, and infants with biliary atresia have presented with normal stools. There is a high specificity of persistent pale stools.
Is the infant receiving total parenteral nutrition (TPN)? TPN may cause direct hyperbilirubinemia by an unknown mechanism and usually does not occur until the infant has been on TPN for >2 weeks. It is more common in sick premature infants.
Is the infant gaining weight? Failure to gain weight can be seen in neonatal hepatitis and some metabolic diseases.
Does the infant appear sick? Infants with cholestatic jaundice caused by bacterial sepsis appear acutely ill. Infection may cause hepatocellular damage, leading to increased direct bilirubin levels. Infants with urinary tract infection, galactosemia, tyrosinemia, hypopituitarism, fructosemia, hemochromatosis, any metabolic disorder, acute common duct obstruction, gallstones with cholestatic jaundice, or hemolysis can also appear ill. These disorders require immediate diagnosis and treatment.
Did direct hyperbilirubinemia occur only after feedings had been established? This suggests that a metabolic disorder such as galactosemia may be present.
Have any risk factors been identified? The most important risk factors include low gestational age, early or prolonged exposure to parenteral nutrition, lack of enteral feeding, and sepsis. Episodes of sepsis can be associated with an increase of 30% in the bilirubin level. Other risk factors include neonatal hepatitis, congenital infections, ABO incompatibility, and trisomy 21. Anesthesia may be a risk factor with direct bilirubin levels being higher in the spinal and epidural group than the inhalation group at 24 hours.
Is the infant being treated for jaundice for another condition and not improving? Any infant who is being treated for jaundice and whose jaundice does not resolve or improve needs to be evaluated for cholestasis.
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