Sodium CSF

The Sodium CSF test measures the concentration of sodium ions in your cerebrospinal fluid, the clear liquid that cushions and nourishes your brain and spinal cord. It is performed on a sample collected during a lumbar puncture, often alongside other CSF studies such as glucose, protein, chloride, and cell counts.

Sodium helps regulate fluid movement and electrical activity in the nervous system. Measuring it in CSF gives your care team a snapshot of the salt and water balance within the central nervous system and can provide supporting information when evaluating symptoms that affect the brain or spinal cord.

Clinicians usually order CSF sodium as part of a broader lumbar puncture panel when investigating infections, inflammation, bleeding, changes in mental status, severe headaches, new neurologic deficits, or complications after neurosurgery. CSF sodium can also reflect shifts caused by body-wide sodium or water problems and by therapies that intentionally change osmotic balance.

While CSF sodium by itself rarely makes a diagnosis, it can help support or refine the clinical picture when interpreted with other CSF results and blood tests. Results may contribute to the assessment of meningitis, encephalitis, subarachnoid hemorrhage, and disorders of salt and water regulation. The analysis is low risk, but it relies on a spinal tap, which can cause temporary discomfort, headache, or, rarely, infection or bleeding.

Your laboratory compares the result to a reference interval specific to cerebrospinal fluid. Your clinician will interpret it together with your blood sodium level, other CSF measurements, your symptoms, imaging, and treatments you may be receiving.

A value only slightly outside the reference interval can occur with dehydration, recent intravenous fluids, diuretics, or osmotic therapies. Larger or persistent differences, especially when combined with abnormal CSF protein, glucose, or cell counts, may point to infection, inflammation, bleeding, or problems with the body’s regulation of water and salt. Depending on the overall picture, your clinician may recommend repeat testing, additional blood work, imaging, antimicrobial treatment, fluid or medication adjustments, and close follow up.