CSF Reference Values for Febrile Infants Without Infection

Previous reference ranges for normal cerebrospinal fluid (CSF) values in infants are based on findings from small studies that did not exclude infants with viral disease. To better characterize normal values, investigators retrospectively evaluated CSF profiles of infants (age range, 1–90 days) at a pediatric medical center in Utah from 1996 to 2002 who met the following criteria: rectal temperature ≥38°C, negative bacterial cultures, negative enteroviral polymerase chain reaction testing, term birth (≥37 weeks' gestation), no antibiotics within 48 hours, and no herpes simplex virus infection.

Of 823 infants, 743 had atraumatic lumbar punctures (red blood cell count ≤1000/mm³). CSF white blood cell (WBC) counts >14.5/ mm³ were considered statistical outliers (presumed due to unidentified viral infections) and were excluded. In the remaining 677 patients with atraumatic lumbar punctures, mean and median CSF WBC counts were 4.3/mm³ and 3.0/mm³, respectively (range, 0–12/mm³). Infants in the first month of life, compared to those in the second and third months of life, had significantly higher mean CSF WBC counts (6.1/mm³ vs. 3.1/mm³ and 3.0/mm³) and mean CSF protein concentrations (75.4 mg/dL vs. 58.9 and 39.2 mg/dL); mean CSF glucose concentrations were similar in the first and second months and significantly lower than in the third month (45.3 mg/dL, 48.0 mg/dL, and 57.7 mg/dL). Traumatic lumbar puncture did not significantly affect WBC count norms, with mean and median counts of 6.5/mm³ and 5.0/mm³, respectively (range, 0–16/mm³).