Differences in total protein concentration, nucleated cell count, and red blood cell count among sequential samples of cerebrospinal fluid from horses.
OBJECTIVE
To examine total protein concentration and cell counts of sequentially collected samples of CSF to determine whether blood contamination decreases in subsequent samples and whether formulas used to correct nucleated cell count and total protein concentration are accurate.


METHODS
Case series.


METHODS
22 horses.


METHODS
For each horse, 3 or 4 sequential 2-ml samples of CSF were collected from the subarachnoid space in the lumbosacral region into separate syringes, and blood was obtained from the jugular vein. Total protein concentration, nucleated cell count, and RBC counts were determined in all samples.


RESULTS
Among 3 sequential samples, total protein concentration and RBC count were significantly lower in samples 2 and 3, compared with sample 1. Nucleated cell count was significantly lower in sample 3, compared with sample 1. Among 4 sequential samples, total protein concentration and RBC count were significantly lower in samples 2, 3, and 4, compared with sample 1. Nucleated cell count was significantly lower in samples 3 and 4, compared with sample 1. For 3 correction formulas, significant differences in corrected values for nucleated cell count and total protein concentration were detected between sample 1 and sample 3 or 4.


CONCLUSIONS
Because iatrogenic blood contamination decreases in sequential CSF samples, a minimum of 3 samples should be collected before submitting the final sample for analysis. Formulas to correct nucleated cell count and total protein concentration are inaccurate and should not be used to correct for blood contamination in CSF samples.
Sweeney
C R
CR
Department of Clinical Studies, New Bolton Center, School of Veterinary Medicine, University of Pennsylvania, Kennett Square 19348-1692, USA.
Russell
G E
GE
D000818:Animals; D001259:Ataxia / Q000134:cerebrospinal fluid / Q000662:veterinary; D002452:Cell Count / Q000662:veterinary; D002555:Cerebrospinal Fluid / Q000737:chemistry / Q000166:cytology*; D002556:Cerebrospinal Fluid Proteins / Q000032:analysis*; D004906:Erythrocyte Count / Q000662:veterinary; D006734:Horse Diseases / Q000134:cerebrospinal fluid; D006736:Horses / Q000134:cerebrospinal fluid*; D012016:Reference Values; D013048:Specimen Handling / Q000662:veterinary; D013118:Spinal Cord Diseases / Q000134:cerebrospinal fluid / Q000662:veterinary; D013129:Spinal Puncture / Q000662:veterinary
D002556:Cerebrospinal Fluid Proteins