• Jaundice that appears in a newborn <24 hour old is most likely nonphysiologic & needs further evaluation
  • Visible jaundice in the feet may be an indication to check bilirubin level

• Visual estimation of bilirubin level is often inaccurate & unreliable

Transcutaneous Bilirubinometry (TcB)

• A noninvasive way to measure serum bilirubin using handheld devices
• May be used as an initial screening test to detect possible development of hyperbilirubinemia
• Said to be equivalent to total serum bilirubin & may decrease the need for more invasive TSB measurements; however, more studies may be needed to validate tests that measure TcB

Total Serum Bilirubin (TSB)

• Measured if jaundice appears excessive for an infant’s age, when TcB level is >200 µmol/L (12 mg/dL), or if there is any doubt about the degree of jaundice
• Often the only test needed for infants who present with moderate jaundice on the 2nd or 3rd day of life & who do not have features suggesting pathologic jaundice

Lab tests for determining cause of jaundice

• Lab tests that will be requested will depend on the indications found in an infant
• Hematology: Hemoglobin & hematocrit, direct Coomb’s test, peripheral blood film, reticulocyte count, blood type & Rh determination in infant & mother
• Screening for G6PD deficiency in infants from high-risk populations
• Total & conjugated bilirubin to identify cholestasis
• Liver function tests: ALT, AST, GGT, alkaline phosphatase
  • A GGT/ALT ratio >1 is highly suggestive of biliary obstruction

• Sepsis evaluation in infants who appear ill
  • Urinalysis, urine culture
  • Tests for parasitic & viral infections

• Measurement of end tidal carbon dioxide in breath as an index of bilirubin production
• Serum albumin to help evaluate risk of bilirubin toxicity
• Thyroid function tests
• Imaging of the liver & biliary tract including ultrasonography & radionuclide imaging

Clinical Assessment of Severity

• Jaundice appears in a cephalo-caudal direction
• For clinical assessment, the Kramer’s Rule may be used to estimate the range of indirect bilirubin levels

Area	Level	Indirect Bilirubin
		µmol/L	mg/dl
Head & neck	1	68-133	4-8
Upper trunk	2	85-204	5-12
Lower trunk & thighs	3	136-272	8-16
Arms & lower legs	4	187-306	11-18
Palms & soles	5	≥306	≥18