What labwork is recommended for a 2-week newborn exam?

From the Guidelines

At the 2-week newborn exam, recommended laboratory tests include a repeat newborn screening test if the initial screen was done before 24 hours of life, as well as assessments for jaundice, such as total serum bilirubin test, if the baby appears jaundiced. The specific tests ordered should be tailored to the infant's risk factors, clinical presentation, and results of previous screenings 1.

Key Considerations

• A repeat newborn screening test is recommended if the initial screen was done before 24 hours of life, to ensure that certain metabolic disorders are not missed due to early discharge 1.
• Hemoglobin screening is indicated for infants at risk for anemia.
• If the baby appears jaundiced, a total serum bilirubin test should be performed to assess for hyperbilirubinemia, as indicated in the management of hyperbilirubinemia in the newborn infant 35 or more weeks of gestation 1.
• For infants with risk factors or concerning symptoms, additional tests may include a complete blood count to evaluate for infection or anemia, blood glucose monitoring for feeding difficulties, and urine culture if urinary tract infection is suspected.
• Thyroid function tests may be considered if the initial newborn screen was abnormal or if there are clinical concerns for thyroid dysfunction.

Laboratory Tests

• Repeat newborn screening test
• Total serum bilirubin test for jaundiced infants
• Hemoglobin screening for infants at risk for anemia
• Complete blood count for infection or anemia
• Blood glucose monitoring for feeding difficulties
• Urine culture for urinary tract infection
• Thyroid function tests if initial newborn screen was abnormal or if clinical concerns for thyroid dysfunction exist. These tests help identify common neonatal conditions that benefit from early intervention, as many metabolic, hematologic, and infectious conditions may not be symptomatic initially but can cause significant harm if left untreated 1.

From the Research

Labwork for 2-Week Newborn Exam

• The routine newborn assessment should include an examination for size, macrocephaly or microcephaly, changes in skin color, signs of birth trauma, malformations, evidence of respiratory distress, level of arousal, posture, tone, presence of spontaneous movements, and symmetry of movements 2.
• Total and direct bilirubin levels should be measured in newborns with jaundice 2.
• A complete blood count should be obtained in those with pallor or a ruddy complexion 2.
• There is no specific labwork recommended for a 2-week newborn exam in the provided studies, but the American Academy of Pediatrics (AAP) recommends screening for anemia between the ages of 9 to 12 months with additional screening between the ages of 1 and 5 years for patients at risk 3.
• Newborn screening programmes based on dried blood spots are used to screen for various conditions, including phenylketonuria and congenital hypothyroidism 4.
• The red cell distribution width (RDW) has been proposed as a diagnostic aid in the evaluation of pediatric anemias, and may be useful in screening for anemia at the 12-month well-baby examination 5.

Jaundice Screening

• A jaundice colour card can be used by parents to screen for neonatal jaundice, and has been validated by comparing it with total serum bilirubin levels 6.
• The jaundice colour card measurements at the infant's forehead, cheek, and sternum showed strong correlations with total serum bilirubin 6.

Anemia Screening

• The AAP recommends screening for anemia between the ages of 9 to 12 months with additional screening between the ages of 1 and 5 years for patients at risk 3.
• The RDW alone appears to be predictive of identifiable causes of anemia when used in screening 12-month-old babies who are otherwise healthy 5.