Utilization of automated systems to provide cerebrospinal fluid (CSF) cell counts warrants new reference ranges, according to a study published in the January issue of Clinical Biochemistry. The researchers propose new CSF cell count reference ranges of < 4 cells/μL for lymphocytes, < 3 cells/μL for monocytes, and < 3 cells/μL for granulocytes. They further determined that automated systems’ ability to differentiate mononuclear cells is of limited differential diagnostic utility. CSF cell counts have traditionally been manually performed using a microscope and cell counting chamber. The downsides of this technique are that it is time-consuming, requires trained laboratory personnel to be present, and there can be high variability among trained staff. While the performance of automated systems and manual counts is similar, automated systems reduce turnaround time, lower costs, and can provide more detailed cell differentiation than manual analysis. Cells are usually classified as erythrocytes, granulocytes, and mononuclear cells using manual analysis, while automated systems can further separate mononuclear cells into lymphocytes and monocytes based on size, absorbance, and light-scattering characteristics. The researchers used the Siemens ADVIA 2120i automated counter to establish a reference range from samples in 80 neurologically healthy volunteers (mean age 67 years) undergoing orthopedic surgery, with […]
Utilization of automated systems to provide cerebrospinal fluid (CSF) cell counts warrants new reference ranges, according to a study published in the January issue of Clinical Biochemistry. The researchers propose new CSF cell count reference ranges of < 4 cells/μL for lymphocytes, < 3 cells/μL for monocytes, and < 3 cells/μL for granulocytes. They further determined that automated systems’ ability to differentiate mononuclear cells is of limited differential diagnostic utility.
CSF cell counts have traditionally been manually performed using a microscope and cell counting chamber. The downsides of this technique are that it is time-consuming, requires trained laboratory personnel to be present, and there can be high variability among trained staff. While the performance of automated systems and manual counts is similar, automated systems reduce turnaround time, lower costs, and can provide more detailed cell differentiation than manual analysis. Cells are usually classified as erythrocytes, granulocytes, and mononuclear cells using manual analysis, while automated systems can further separate mononuclear cells into lymphocytes and monocytes based on size, absorbance, and light-scattering characteristics.
The researchers used the Siemens ADVIA 2120i automated counter to establish a reference range from samples in 80 neurologically healthy volunteers (mean age 67 years) undergoing orthopedic surgery, with a sample extracted prior to spinal anesthesia. For comparison, cells were manually counted in 32 1-square-millimeter areas by two experienced laboratory technicians, with the average used for comparison. To evaluate the differential diagnostic ability of utilizing lymphocytes and monocytes cell counts, the researchers used hospital records from 175 patients with elevated CSF mononuclear pleocytosis.
Results showed that there was good correlation between automated and manual leukocyte counts for samples with erythrocyte counts < 250 cells/μL. The new suggested reference ranges were determined using the 95th percentile for the neurologically healthy volunteers.
“The objection could be raised that a patient with an automated cell count . . . would be classified as having a normal cell count using these new suggested reference ranges, despite having a total cell count of 7 cells/μL which is above the limit of 5 cells/μL of today’s reference ranges,” write the authors, led by Daniel Bremell, from the University of Gothenburg in Sweden. “However, we consider the probability of this being of any clinical importance as very low.”
In the differential diagnosis analysis, comparisons were made between patients diagnosed with Lyme neuroborreliosis and viral infection. There were no significant differences between these two groups regarding cell counts of lymphocytes and monocytes.
