Cerebrospinal fluid is a clear fluid surrounding the brain and the spinal cord. It is collected via a lumbar puncture under sterile conditions. CSF is analyzed to confirm certain diseases such as meningitis, certain infections, autoimmune diseases, and tumors. Common tests performed on CSF include protein and glucose levels, cell counts and differential count, microscopic examination, stains, and cultures. CSF may also be tested for glutamine, lactate dehydrogenase, lactic acid, tumor markers, and C-reactive proteins. When necessary, virus titers or cultures, Venereal Disease Research Laboratory (VDRL) tests, Cryptococcus antigen assays, India ink stains, angiotensin-converting enzyme (ACE) levels, or other tests are requested. Depending on the clinical condition, further tests may be required. To avoid hemolysis and specimen misplacement, all specimens should be transported to the laboratory as soon as possible.