Diagnosis
- 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
Laboratory Tests
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
Assessment
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 |