CSF Analysis
Also known as: Spinal fluid analysis
Formal name: Cerebrospinal fluid analysis
Related tests: Glucose, Total Protein, CBC (Complete Blood Count), Lactate, Protein Electrophoresis, Antibody Tests, AFB Smear and Culture, Blood Culture, Herpes, Lyme Disease, Rubella, Syphilis, West Nile Virus
Chemical tests — a few routine tests are usually performed on CSF samples.
CSF protein electrophoresis — separates different types of protein. Oligoclonal bands may be seen with multiple sclerosis and Lyme disease.
CSF IgG (Immunoglobulin G) — increased in some conditions, such as multiple sclerosis, herpes encephalitis, connective tissue diseases.
Myelin basic protein — seen when the covering of nerves (myelin) breaks down, such as with multiple sclerosis.
CSF lactic acid — often used to distinguish between viral and bacterial meningitis. The level will usually be increased with bacterial and fungal meningitis while it will remain normal or only slightly elevated with viral meningitis.
CSF lactate dehydrogenase (LD) — used to differentiate between bacterial and viral meningitis; may also be elevated with leukemia or stroke.
CSF glutamine — may be increased with liver disease: hepatic encephalopathy and Reye syndrome
CSF C-reactive protein (CRP) is an acute phase reactant and is elevated with inflammation. It is markedly increased with bacterial meningitis. Since it is very sensitive even with early bacterial meningitis, it is often used to distinguish between bacterial and viral meningitis.
Tumor markers — Carcinoembryonic antigen (CEA), alpha-fetoprotein (AFP), and hCG may be increased in cancers that have spread from other sites in the body (metastatic).
If any of the initial tests are abnormal or if the doctor has reason to suspect a specific condition, then additional testing may be ordered. This may include one or more of the following:
- CSF total cell counts
- Red blood cell (RBC) count. Normally no red blood cells are present in the CSF. The presence of red blood cells may indicate bleeding into the CSF or may indicate a “traumatic tap” - blood that leaked into the CSF sample during collection.
- White blood cell (WBC) count. Normally less than 5 cells are present in the adult. A significant increase in white blood cells in the CSF is seen with infection or inflammation of the CNS.
- CSF WBC differential
Small numbers of lymphocytes, monocytes (and, in neonates, neutrophils) are normal in a sample of CSF. There may be:- an increase in neutrophils with a bacterial infection
- an increase in lymphocytes with a viral infection
- sometimes an increase in eosinophils with a parasitic infection
- abnormal and increased numbers of WBCs may be seen with leukemia that is present in the CNS
- abnormal cells may be present with cancerous tumors
- immune disorders of the CSF, such as multiple sclerosis, may also cause a slight increase in lymphocytes.
There may be an increase in the different types of WBCs with a variety of other conditions, including brain abcess, following seizures or bleeding within the brain or skull, metastatic tumor, Guillain-Barré syndrome, and inflammatory disorders such as sarcoidosis.
- CSF cytology – a cytocentrifuged sample is treated with a special stain and examined under a microscope for abnormal cells. This is often done when a CNS tumor or metastatic cancer is suspected. The presence of certain abnormal cells, such as tumor cells or immature blood cells, can indicate what type of cancer is involved.
