Reference Ranges Established for Automated Cerebrospinal Fluid Cell Count

Cerebrospinal fluid (CSF) cell count is an important analysis in the investigation of central nervous system (CNS) infections, and new reference ranges for leukocytes in the CSF have been established.

The references ranges for granulocytes, lymphocytes, and monocytes in the CSF were originally based on manual counts, but since the introduction of automated cell counters, these ranges have not been revised, or abnormalities connected to diseases.

Infectious disease specialists at the Sahlgrenska Academy (Gothenburg, Sweden) analyzed CSF from 80 neurologically healthy volunteers. For the differential diagnosis section, they analyzed cell counts and hospital records from 175 patients with CSF mononuclear pleocytosis, which is an increased cell count particularly an increase in white blood cell (WBC) count, in a bodily fluid, such as CSF.

Manual CSF cell counting was performed and compared with automated CSF cell counting was performed on a ADVIA 2120i instrument within one hour of sampling using the ADVIA 2120i CSF Assay (Siemens, Erlangen, Germany). The method requires 300 μL of CSF and reports counts for erythrocytes, lymphocytes, monocytes and granulocytes, which are differentiated on the basis of size, absorbance and light scattering characteristics.

Correlation between manual and automated cell counts was excellent for erythrocytes, but was lower for leukocytes, when erythrocyte counts were lower than 250 cells/μL. For the neurologically healthy volunteers studied in the reference range section, the 95th percentile was 3.0 cells/μL for lymphocytes, 1.0 cell/μL for monocytes, and 1.0 cell/μL for granulocytes. In the differential diagnosis section, comparisons were done between the groups with Lyme neuroborreliosis and viral CNS infection. There were no significant differences between these two groups regarding cell counts; neither for lymphocytes, median 58 cells/μL vs. 72 cells/μL; nor for monocytes, median 13 cells/μL vs. 16 cells/μL; nor for granulocytes, median 1 cell/μL vs. 2 cells/μL.

The authors suggested that new reference ranges of less than 4 cells/μL for lymphocytes, less than 3 cells/μL for monocytes, and less than 3 cells/μL for granulocytes for CSF leukocytes when automatically analyzed with the Siemens ADVIA 2120i. The separation of mononuclear cells into lymphocytes and monocytes did not facilitate the discrimination between Lyme neuroborreliosis and viral CNS infection. The study was published in the January 2014 issue of the journal Clinical Biochemistry.

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Sahlgrenska Academy
Siemens