When evaluating suspected neonatal sepsis, CRP and Procalcitonin should be obtained when?

• A. Once with initial work-up for sepsis
• B. Prior to initiating antibiotic treatment and in 24 hours
• C. Only after 72 hours
• D. Repeated serially over 1-3 days

Answer: (D)

Tracking CRP and procalcitonin over time is key when suspected neonatal sepsis. These markers don’t give a reliable picture from a single reading because their levels change as infection evolves and in response to treatment. Neonates can have inflammatory markers rise or fall for reasons beyond infection, and CRP can lag while procalcitonin can be influenced by perinatal physiology, so following the trend is more informative than one value alone.

Obtaining repeated measurements over the first 1–3 days lets you see the trajectory: if the markers fall with antibiotic therapy, that supports improvement and can help stop antibiotics sooner; if they remain elevated or rise, it suggests persistent infection or treatment failure and may prompt continued therapy or further workup. A one-time test at the start may miss developing sepsis or a delayed response, and waiting until 72 hours would delay important decisions about treatment duration.