Normative cerebrospinal fluid profiles in febrile infants.

OBJECTIVE: To describe the cerebrospinal fluid (CSF) profiles of febrile infants aged 1 to 90 days with negative bacterial culture test results and negative results for enteroviruses with polymerase chain reaction. STUDY DESIGN: Statistical analysis of a retrospective cohort. RESULTS: CSF profiles from 823 infants with negative test results for infection were analyzed. For 677 infants with atraumatic lumbar punctures (red blood cell [RBC] count < 1000/mm(3)), the mean and median CSF white blood cell (WBC) counts were 4.3/mm(3) and 3.0/mm(3), respectively, with a range from 0 to 12/mm(3). Mean CSF WBC counts (6.1/mm(3) versus 3.1/mm(3) and 3.0/mm(3)) and protein levels (75.4 mg/dL versus 58.9 mg/dL and 39.2 mg/dL) were higher in the first month compared with months 2 and 3, respectively (P < .001 for all). CSF glucose levels were lower in the first month compared with month 3 (45.3 mg/dL versus 48.0 mg/dL and 57.7 mg/dL; P < .001). Increasing RBC counts were statistically associated with increasing WBC counts (P < .001). However, the contribution of RBC < 10,000/mm(3) was small, and the reference range for WBC in uninfected infants with traumatic lumbar punctures was 0 to 16/mm(3). CONCLUSION: CSF WBC counts in febrile infants without evidence of bacterial or enteroviral infection, even in those with traumatic lumbar puncture, are lower than reported in pediatric references.