Blood inflammatory marker threshold values for well-appearing, febrile infants 22 to 60 days of age
Blood inflammatory marker threshold values for well-appearing, febrile infants 22 to 60 days of age
Inflammatory marker
Abnormal value
Procalcitonin
>0.5 ng/mL
C-reactive protein
>20 mg/L
Absolute neutrophil count
>4000/mm3 or 5200/mm3*
Blood inflammatory marker values above these thresholds suggest an increased risk of invasive bacterial illness (IBI) in febrile young infants 22 to 60 days old. Procalcitonin has the best ability to identify IBI in well-appearing febrile young infants if it is rapidly available (ie, within 1 to 2 hours). When applying these thresholds, ensure concordance with units and range in use by the laboratory performing the test. For additional information regarding the utility of blood inflammatory markers in febrile young infants, refer to UpToDate topics on the outpatient evaluation and management of infants 29 to 90 days old.
* These thresholds are derived from two different decision models. An elevated absolute neutrophil count is useful for identifying elevated risk for invasive bacterial infection but is not as accurate as procalcitonin or C-reactive protein.
Reference:
Pantell RH, Roberts KB, Adams WG, et al. Evaluation and Management of Well-Appearing Febrile Infants 8 to 60 Days Old. Pediatrics 2021; 148.
