Comparison of Serum Procalcitonin and C-reactive Protein Levels in Late Onset Neonatal Sepsis

Abstract

Background: Neonatal mortality and sequelae can be decreased by promptly diagnosing neonatal sepsis (NS). Although the gold standard for diagnosis is blood culture, additional tests such as acute-phase reactants — procalcitonin (PCT) and C-reactive protein (CRP) — are helpful for early detection. Some studies suggest that PCT increases earlier than CRP in septic conditions. Objectives: The present study aimed to compare CRP and PCT levels for diagnosing late-onset NS. Methods: In this prospective observational study, 40 full-term neonates (older than three days and weighing over 2.5 kg) with suspected sepsis were enrolled at the neonatal intensive care unit (NICU) of Ghaem Hospital, affiliated with Mashhad University of Medical Sciences. Neonates with congenital anomalies, metabolic disorders, or chromosomal syndromes were excluded. All patients underwent a standard sepsis workup, including blood culture, CRP measurement, and serum PCT level assessment on admission and three days after initiating antibiotic therapy. Sensitivity, specificity, and diagnostic accuracy were calculated using blood culture results as the reference standard. Results: Newborns with confirmed sepsis had significantly elevated serum levels of both CRP and PCT. At baseline, the mean PCT level was 10.77 ng/mL, and the mean CRP level was 31.817 mg/dL. Post-treatment, these levels decreased to 2.75 ng/mL for PCT and 10.80 mg/dL for CRP. Procalcitonin demonstrated a sensitivity of 77.5% and specificity of 70%, while CRP showed the same sensitivity (77.5%) but higher specificity (87.5%). Conclusions: Both CRP and PCT are valuable adjuncts for diagnosing NS. However, due to its earlier rise in the course of infection, PCT may be more effective for early detection.