From the Guidelines
Procalcitonin (PCT) testing in neonates during the first week of life has limited accuracy and should be interpreted with caution. PCT levels naturally rise after birth in healthy neonates, peaking at 24-48 hours of life before gradually declining, making it difficult to distinguish between this physiological elevation and true infection 1. For optimal use, gestational age-specific and postnatal age-specific reference ranges should be employed when interpreting results. PCT is most valuable when used as part of a comprehensive evaluation including clinical assessment, complete blood count, C-reactive protein, and blood cultures, rather than as a standalone test.
Key Considerations
- Serial measurements showing rising levels are more informative than single values.
- The test performs better after 72 hours of life when physiological elevations have begun to decline.
- Factors that can affect PCT levels in neonates include maternal fever, prolonged rupture of membranes, chorioamnionitis, perinatal asphyxia, and hemodynamic instability.
- Despite these limitations, PCT may still offer value in antimicrobial stewardship by helping to safely discontinue antibiotics in neonates with low clinical suspicion of infection and normal or rapidly decreasing PCT values, potentially reducing unnecessary antibiotic exposure 1.
Clinical Application
In clinical practice, the use of PCT should be guided by the principles of minimizing harm and maximizing benefit. Given the limited accuracy of PCT in neonates during the first week of life, it is crucial to interpret PCT results in the context of the overall clinical picture, including clinical assessment, laboratory findings, and the presence of risk factors for infection 1. By doing so, clinicians can make more informed decisions about the use of antibiotics and other interventions, ultimately improving outcomes for neonates.
From the Research
Procalcitonin in Neonates
- Procalcitonin is considered an excellent marker for severe, invasive bacterial infection in children, including neonates 2.
- The use of procalcitonin in diagnosing neonatal bacterial infection can be complicated, but it results in higher specificity than C-reactive protein if used correctly 2.
- Procalcitonin levels have been shown to correlate with the severity of disease, such as urinary tract infections and sepsis, making it a useful prognostic marker 2, 3.
Accuracy of Procalcitonin in the First Week of Life
- Studies have found that procalcitonin levels can be significantly higher in neonates with sepsis compared to those without infection 3, 4.
- Procalcitonin measurement at 24 hours of age may be helpful in the prompt diagnosis of early-onset neonatal sepsis 4.
- However, procalcitonin levels can also be influenced by non-infectious conditions, such as prenatal use of antibiotics, surfactant administration, and ventilator application 5.
- Reference ranges for procalcitonin levels in preterm newborns have been established, showing a trend to increase after birth up to a peak between 24 and 48 hours of life, and then decrease 6.
Factors Influencing Procalcitonin Levels
- Gestational age and birth weight can affect procalcitonin levels, with preterm newborns having higher levels than term newborns 5, 6.
- Respiratory difficulty and the use of antibiotics or ventilators can also influence procalcitonin levels 5.
- Further studies are needed to fully understand the factors that affect procalcitonin levels in neonates and to establish clear reference ranges for diagnosis and prognosis 2, 3, 5, 4, 6.