Sodium concentration in cerebrospinal fluid (CSF)

Why This Test Matters

Sodium is essential for nerve and muscle function, but abnormal levels in CSF can signal issues like inflammation, infections, or structural problems in the brain. Your doctor may order this test if you have symptoms like headaches, neurological deficits, or signs of a condition like meningitis, multiple sclerosis, or brain tumors.

When You Might Need It

This test is often performed when evaluating symptoms such as severe headaches, seizures, confusion, or weakness that may suggest abnormal fluid pressure or brain inflammation. It’s also used in diagnosing conditions like idiopathic intracranial hypertension (pseudotumor cerebri) or certain types of brain swelling.

What to Expect Before the Test

No special preparation is needed. A healthcare provider will collect a small sample of CSF through a procedure called a lumbar puncture (spinal tap), where a needle is inserted into your lower back to draw fluid from the spinal canal.

What the Results Mean

Results are compared to standard ranges for sodium in CSF, which can vary slightly by lab. Low sodium levels (hyponatremia) may indicate conditions like meningitis or brain edema, while high levels (hypernatremia) could suggest bleeding, tumors, or other structural abnormalities.