Contributor: Eric Miller, MD
- A cell count is performed on tubes 1 and 4 to account for changes that may occur from blood entering the first sample from the needle insertion
- Tube 2 and 3 are usually used for the other studies like protein levels, glucose levels and gram staining
- Protein levels are often elevated in bacterial meningitis but can be helpful in diagnosis conditions like multiple sclerosis
- Glucose levels are typically low in bacterial meningitis due to the use of glucose by bacteria
- Cell counts above 3-5 cells are typically abnormal, but cell counts can vary widely depending on the type of meningitis (viral vs. bacterial) and how long the infection has been present.
- Cell type and differential can indicate viral vs. bacterial meningitis
- Neutrophils are more associated with bacterial causes
- Lymphocytes are more associated with viral etiologies
- CSF cultures are used to identify the cause of bacterial meningitis but can take days to result.
- A gram stain can help determine if any bacteria are present as well as cell types present.
- Jain, R. Chang, WW. Emergency Department Approach to the Patient with Suspected Central Nervous System Infection. Emerg Med Clin North Am. 2018 Nov;36(4):711-722. doi: 10.1016/j.emc.2018.06.004.
Summarized by Jackson Roos, MS3 | Edited by Erik Verzemnieks, MD