Which blood tests are useful in suspected bacterial meningitis?

Updated: Jul 16, 2019
  • Author: Rodrigo Hasbun, MD, MPH; Chief Editor: Michael Stuart Bronze, MD  more...
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In patients with bacterial meningitis, a complete blood count (CBC) with differential will demonstrate polymorphonuclear leukocytosis with a left shift. Useful elements of the metabolic panel include the following:

  • Serum electrolytes, to determine dehydration or syndrome of inappropriate secretion of antidiuretic hormone (SIADH)
  • Serum glucose (which is compared with the CSF glucose)
  • Blood urea nitrogen (BUN) or creatinine and liver profile, to assess organ function and adjust antibiotic dosing
  • HIV testing

The serum glucose level may be low if glycogen stores are depleted, or they may be high in infected patients with diabetes.

A coagulation profile and platelet count are indicated in cases of chronic alcohol use, chronic liver disease, or suspected disseminated intravascular coagulation (DIC). Patients with coagulopathies may require platelets or fresh frozen plasma (FFP) before LP.

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