Definition

CSF total protein is a test to determine the amount of protein in cerebrospinal fluid (CSF). CSF is a clear fluid that is in the space around the spinal cord and brain.

How the Test is Performed

A sample of CSF is needed [1 to 5 milliliters (ml)]. A lumbar puncture (spinal tap)is the most common way to collect this sample. Rarely, other methods are used for collecting CSF such as:

• Cisternal puncture
• Ventricular puncture
• Removal of CSF from a tube that is already in the CSF, such as a shunt or ventricular drain.

After the sample is taken, it is sent to a lab for evaluation.

Why the Test is Performed

You may have this test to help diagnose:

• Tumors
• Infection
• Inflammation of the central nervous system
• Guillain-Barré syndrome
• Vasculitis
• Blood in the spinal fluid
• Multiple sclerosis (MS)

Normal Results

The normal protein range varies from lab to lab, but is typically 15 to 60 milligrams per deciliter (mg/dL) or 0.15 to 0.6 milligrams per milliliter (mg/mL).

Normal value ranges may vary slightly among different labs. Talk to your health care provider about the meaning of your specific test results.

The examples above show the common measurements for results for these tests. Some labs use different measurements or may test different specimens.

What Abnormal Results Mean

An abnormal protein level in the CSF suggests a problem in the central nervous system.

An increased protein level may be a sign of a tumor, bleeding, nerve inflammation, infection or injury. A blockage in the flow of spinal fluid can cause the rapid buildup of protein in the lower spinal area.

A decrease in the protein level can mean your body is rapidly producing spinal fluid or you have a more generalized protein deficiency.

References

De Luca GC, Griggs RC, Johnston SC. Approach to the patient with neurologic disease. In: Goldman L, Cooney KA, eds. Goldman-Cecil Medicine. 27th ed. Philadelphia, PA: Elsevier; 2024:chap 366.

Karcher DS, McPherson RA. Cerebrospinal, synovial, serous body fluids, and alternative specimens. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 24th ed. Philadelphia, PA: Elsevier; 2022: chap 30.

Rosenberg GA. Brain edema and disorders of cerebrospinal fluid circulation. In: Jankovic J, Mazziotta JC, Pomeroy SL, Newman NJ, eds. Bradley and Daroff's Neurology in Clinical Practice. 8th ed. Philadelphia, PA: Elsevier; 2022:chap 88.

Schnapp BH, Jewell C. Central nervous system infections. In: Walls RM, ed. Rosen's Emergency Medicine: Concepts and Clinical Practice. 10th ed. Philadelphia, PA: Elsevier; 2023:chap 95.