- 1-3 mL of Cerebrospinal Fluid (CSF) is collected into each sterile plastic tube; typically 4 tubes are collected
- CSF is collected by lumbar puncture ("spinal tap") using sterile technique
Typical use of each tube:
- Tube 1 - For chemistry and serology testing
- Tube 2 - For microbiology
- Tube 3 or 4 - For miscellaneous testing
- Tube 3 or 4 – For cell count
CSF WBC Calculator: 
Cell counts from CSF give a count of the number of red blood cells (RBCs) and white blood cells (WBCs) in each mm3. Additional information is obtained with the WBC differential which is included in cell counts; the differential supplies information about the type of WBC’s that make up the total WBC cell count.
General information about CSF
- Cerebrospinal Fluid (CSF) is a clear fluid formed in the brain that "bathes" the brain and fills the subarachnoid space.
- CSF is in contact with the extracellular fluid of the brain and its composition is reflective of the brain itself.
- CSF mainly helps in regulation of intracranial pressure (ICP), supply of nutrients to the nervous tissues, and removal of waste products.
- CSF protects the brain and the spinal cord from injury.
- Despite CT and MRI, CSF analysis remains a critical diagnostic tool in the evaluation of neurological disorders.
Table of CSF findings with infection
| Type of infection | WBCs/mm3 | WBC Differential | Protein | Glucose Ratio (Serum:CSF) | Lactate | Opening Pressure |
|---|---|---|---|---|---|---|
| Bacterial | >100 (usually  1000) | Neutrophils dominate in most cases. Lymphocytosis in 10% of cases | Elevated | Normal or decreased | Elevated | Elevated |
| Viral |  300 | Lymphocytosis typical; Neutrophils may dominate early in course | Normal or elevated | Normal (may be decreased in mumps or LCM) | Normal | Normal (typically) |
| Fungal or Tubercular | 500 | Lymphocytosis typical | Elevated | Decreased (typically) | Elevated | Variable |
CSF Formation/Circulation
- In an adult, approximately 150 mL of CSF is in circulation at any moment.
- 500-600 mL of CSF is formed and absorbed daily
- CSF is formed by the choroid plexus, primarily in the lateral ventricles (to a smaller degree in the 3rd and 4th ventricles)
- CSF circulates through the interventricular foramina to the third ventricle, through the cerebral aqueduct into the fourth ventricle and finally to the subarachnoid space covering the brain and spinal cord.
- Following circulation through the subarachnoid space, the CSF enters the intracranial sinuses to be resorbed by the arachnoid villi and granulations
Relationship of blood to CSF
- The blood brain barrier is relatively impervious to cellular compounds; however, CSF is an ultra-filtrate of serum and as such is impacted by the composition of serum
- The blood-CSF barrier is not as impervious and smaller molecular compounds such as glucose, albumin and immunoglobulins will find their way into the CSF from serum, via diffusion.
- A blood specimen drawn at a time close to obtaining CSF is useful for comparison
- CSF glucose level is usually 60% of that of blood glucose level
- CSF protein is typically only 20% derived from the brain and 80% from diffusion from serum into subarachnoid circulating CSF
This section covers CSF cell counts. Other sections provide detailed information on each other components of CSF testing.
CSF WBC Calculator:
Cell count overview
- CSF is typically acellular, with any more than a low count of RBCs or WBCs being abnormal (especially in adults)
- RBCs, when present, most commonly represents traumatic lumbar puncture
- With traumatic lumbar puncture, the amount of RBCs usually decreases by with each tube of CSF (this is the reason why either tube 3 or 4 is submitted for cell counts)
- RBCs in the CSF can result from CNS (Central Nervous System) trauma or hemorrhage
- WBCs in the CSF can occur from CNS infection, inflammation or tumor
- The differential of WBCs cannot distinguish between bacterial and non-bacterial meningitis; although neutrophils typically predominate in bacterial meningitis, this is not a consistent finding
- One study indicates that it is unlikely that a patient has bacterial meningitis unless they have WBCs>5 with >50% of cells being neutrophils
CSF clinical overview
- CSF is obtained to evaluate for infection, inflammation, malignancy, or bleeding in the central nervous system
- Additional special tests (mostly experimental) are increasingly available for the evaluation of other conditions such as multiple sclerosis or dementia
Information gained from Lumbar Puncture and CSF Analysis includes:
- Opening pressure (pressure in the brain)
- Glucose
- Protein
- Cell counts
- Gram stain
- Culture for bacteria, fungus, virus
- Bacterial antigens
- Fungal stains
- Viral testing
- Syphilis testing
- Lyme testing
- CSF immunoglobulin levels
- CSF angiotensin-converting enzyme (Neurosarcoid)
- Tumor markers
- Alpha-fetoprotein (AFP)
- Beta-glucuronidase
- Carcinoembryonic antigen (CEA)
- Human chorionic gonadotropin (HCG)
- Lysozyme (muramidase)
- Lactate in mitochondrial cytopathies
- Other specialized testing as condition dictates
Table of CSF findings with infection
| Type of infection | WBCs/mm3 | WBC Differential | Protein | Glucose Ratio (Serum:CSF) | Lactate | Opening Pressure |
|---|---|---|---|---|---|---|
| Bacterial | >100 (usually 1000) | Neutrophils dominate in most cases. Lymphocytosis in 10% of cases | Elevated | Normal or decreased | Elevated | Elevated |
| Viral | 300 | Lymphocytosis typical; Neutrophils may dominate early in course | Normal or elevated | Normal (may be decreased in mumps or LCM) | Normal | Normal (typically) |
| Fungal or Tubercular | 500 | Lymphocytosis typical | Elevated | Decreased (typically) | Elevated | Variable |
Contraindications to performing lumbar puncture:
- Infection overlying site of needle insertion
- Coagulation defects (most commonly increased PT)
- Increased intracranial pressure; especially with space occupying lesion present (e.g. tumor, abscess) as herniation of the brain is a theoretic risk
- Degenerative joint disease (relative contraindication)
Related laboratory tests include:
- Complete blood count
- Blood culture
- Lyme serology
- Syphilis serology (RPR, VDRL)
This section covers CSF cell counts. Other sections provide detailed information on each other components of CSF testing.
CSF WBC Calculator:
Consult your laboratory for their normal ranges as these may vary somewhat from the ones listed below.
| Conv. Units (cells/mm3) | SI Units (cells ×106/L) | |
|---|---|---|
| RBCs | <5 | <5 |
| WBCs | ||
| Adult | <5 | <5 |
| Child 5-13 yr | <10 | <10 |
| Child 1-4 yr | <20 | <20 |
| Infant <1 yr | <30 | <30 |
| Infant <8 weeks | <50 | <50 |
| Newborn (Term) | <25 | <25 |
| Newborn (Premature) | <30 | <30 |
WBC Differential
| Conv. (%) | SI (fraction) | |
|---|---|---|
| Lymphocytes | ||
| Adult | 40-80 | 0.4-0.8 |
| Children | 5-13 | 0.05-0.13 |
| Newborn | 5-35 | 0.05-0.35 |
| Monocytes | ||
| Adult | 15-45 | 0.15-0.45 |
| Children | 50-90 | 0.5-0.9 |
| Newborn | 50-90 | 0.5-0.9 |
| Neutrophils | ||
| Adult | <6 | <0.06 |
| Children | <8 | <0.08 |
| Newborn | <8 | <0.08 |
This section covers CSF cell counts. Other sections provide detailed information on each other components of CSF testing.
CSF WBC Calculator:
Elevated RBC's occurs in:
- Intracranial hemorrhage
- Trauma to CNS
- Traumatic lumbar puncture
WBC count >500 WBCs/mm3 predominantly neutrophils is suggestive of:
- Infectious causes:
- Amebic encephalomyelitis
- Bacterial meningitis
- Early stages of cerebral abscess
- Early tubercular meningitis
- Early viral meningitis
- Fungal meningitis
- Intracranial abscess
- Noninfectious causes:
- CSF infarct
- Injection of foreign materials into the subarachnoid space
- X-ray contrast medium
- Anticancer drugs
- Metastatic tumor in contact with CSF
- Reaction to CNS hemorrhage
- Reaction to repeated LP
WBC counts of 300–500/µL with preponderantly lymphocytes are suggestive of the following conditions:
- Acute disseminated encephalomyelitis
- Aseptic meningitis due to peptic focus adjacent to meninges
- Bacterial meningitis due to unusual organisms - Listeria species
- Encephalopathy caused by drug abuse
- Fungal meningitis
- Guillain-Barré syndrome (15%)
- Human T-lymphotropic virus type III (HTLV III)
- Multiple Sclerosis
- Parasitic infestation of the CNS
- Polyneuritis
- Sarcoidosis of meninges
- Syphilis of CNS - meningoencephalitis
- Tuberculous meningitis
- Viral meningitis
WBC counts with 40% monocytes occurs in the following conditions
- Chronic bacterial meningitis
- Multiple Sclerosis
- Rupture of brain abscess
- Toxoplasmosis and amebic meningitis
Increased numbers of plasma cells occurs in the following conditions
- Acute viral infections
- Guillain-Barré syndrome
- Lymphocytic reactions
- Multiple Sclerosis
- Parasitic infestations of CSF
- Sarcoidosis
- Subacute sclerosing pan encephalitis (SSPE)
- Syphilitic meningoencephalitis
- Tuberculous meningitis
Eosinophils are present in the following conditions
- Fungal infections
- Idiopathic hypereosinophilic syndrome
- Parasitic infections
- Reaction to foreign materials in CSF (e.g., drugs, shunts)
- Rickettsial infections (Rocky Mountain spotted fever)
- Sarcoidosis
Blast forms such as lymphoblasts or myeloblasts are seen in:
- Acute leukemia
Ependymal and choroidal cells appear in clusters with distinct nuclei and distinct cell walls in:
- Surgical procedure to the CNS
- Trauma to the CNS
Macrophages are found in:
- Viral meningitis
- Tubercular meningitis
- RBCs in spinal fluid
- Contrast media
- Lipids
This section covers CSF cell counts. Other sections provide detailed information on each other components of CSF testing.
CSF WBC Calculator:
N/A as there are no significant conditions associated with a decreased WBCs or RBCs.
This section covers CSF cell counts. Other sections provide detailed information on each other components of CSF testing.
- Bera S et al. Detection of antigen and antibody in childhood tuberculous meningitis. Indian J Pediatr. 2006 Aug; 73(8):675-9
- Burkhart M et al. Use of Cell Count and Differential to Identify Patients with Low Risk for Bacterial Meningitis. Acad Emerg Med 11(5):487-488
- Chavanet P et al. Performance of a predictive rule to distinguish bacterial and viral meningitis. J Infect. 2006 Aug 1; [Epub ahead of print]
- Freedman MS et al. Recommended standard of cerebrospinal fluid analysis in the diagnosis of multiple sclerosis: a consensus statement. Arch Neurol. 2005 Jun;62(6):867-70
- Griffiths PD et al. Malformations of the fetal spine using in utero MR imaging. Cerebrospinal Fluid Research 2005, 2(Suppl 1): S18 doi: 10.1186/1743-8454-2-S1-S18
- Jakka SR et al. Characteristic abnormalities in cerebrospinal fluid biochemistry in children with cerebral malaria compared to viral encephalitis. Cerebrospinal Fluid Research 2006, 3:8 doi: 10.1186/1743-8454-3-8
- Kawashima H et al. Primary biomarkers in cerebral spinal fluid obtained from patients with influenza-associated encephalopathy analyzed by metabolomics. Int j Neurosci. 2006 Aug; 116(8): 927-36
- Narkeviciucte I et al. Aetiological diagnostics of acute bacterial meningitis in children. Scand J Infect Dis. 2006; 38(9): 782-7
- Rikonen R et al. Cerebrospinal fluid insulin-like growth factors IGF-1 and IGF-2 in infantile autism. Dev Med Child Neurol. 2006 Sep; 48(9): 751-5
- Seehusen DA et al. Cerebrospinal Fluid Analysis. Am Fam Phy. 2003;68:1103-8.
- Silverberg G et al. Elevated cerebrospinal fluid pressure in patients with Alzheimer's disease. Cerebrospinal Fluid Research 2006, 3:7 doi: 10.1186/1743-8454-3-7
- The University of Iowa, Department of Pathology LABORATORY SERVICES HANDBOOK, accessed 12/19/2006 at http://www.healthcare.uiowa.edu/path_handbook/handbook/test413.html