Can We Estimate Late-Onset Sepsis by Serial Methemoglobin Levels? An Observational Study in Preterm Neonates

Objective: To assess serial methemoglobin (MetHb) levels in preterm infants as a possible diagnostic method for late-onset sepsis (LOS). Methods: Preterm infants were assigned into two groups: those with culture-proven LOS and controls. Serial MetHb levels were measured. Results: The MetHb values of the LOS group were found to be significantly increased (p < 0.001). The cutoff value for the detection of LOS was calculated as MetHb > 1.75%, optimized for a sensitivity of 81.9% and specificity of 90%. After antimicrobial therapy, MetHb values were found to decrease significantly (p < 0.001). MetHb had an AUC of 0.810 for mortality using the calculated cutoff of >2% (p < 0.005). Conclusions: MetHb levels increase at the onset of LOS and decrease following treatment. MetHb can be added to other sepsis biomarkers as a rapid infectious process indicator for preterm neonates. MetHb > 2% is associated with LOS mortality.