| Test | Normal | Abnormal | Implications |
|---|
| Pressure | 50-180 mm H2O | Increase | Increased ICP |
| | Decrease | Spinal subarachnoid obstruction above puncture site |
| Appearance | Clear, colorless | Cloudy | Infection |
| | Xanthochromic or bloody | Subarachnoid, intracerebral, or intraventricular hemorrhage; spinal cord obstruction; traumatic lumbar puncture (only in initial specimen) |
| | Brown, orange, or yellow | Elevated protein levels, RBC breakdown (blood present for at least 3 days) |
| Protein | 15-50 mg/dl (SI: 0.15-0.5 g/L) | Marked increase | Tumors, trauma, hemorrhage, diabetes mellitus, polyneuritis, blood in CSF |
| | Marked decrease | Rapid CSF production |
| Gamma globulin | 3%-12% of total protein | Increase | Demyelinating disease, neurosyphilis, Guillain-Barré syndrome |
| Glucose | 50-80 mg/dl (SI: 2.8-4.4 mmol/L) | Increase | Systemic hyperglycemia |
| | Decrease | Systemic hypoglycemia, bacterial or fungal infection, meningitis, mumps, postsubarachnoid hemorrhage |
| Cell count | 0-5 WBCs | Increase | Active disease: meningitis, acute infection, onset of chronic illness, tumor, abscess, infarction, demyelinating disease |
| No RBCs | RBCs | Hemorrhage or traumatic lumbar puncture |
| VDRL | Nonreactive | Positive | Neurosyphilis |
| Chloride | 118-130 mEq/L (SI: 118 to 130 mmol/L) | Decrease | Infected meninges |
| Gram stain | No organisms | Gram-positive or gram-negative organisms | Bacterial meningitis |