Protein Electrophoresis (CSF)

Protein electrophoresis of cerebrospinal fluid (CSF) is a laboratory test that separates and identifies CSF proteins using electrophoresis and immunofixation to detect abnormal patterns like oligoclonal bands. It helps diagnose and monitor inflammatory, infectious, or immune-mediated central nervous system disorders (for example, multiple sclerosis) and distinguishes intrathecal immunoglobulin synthesis from systemic protein leakage by comparing CSF and serum.

CSF protein levels reflect blood–brain barrier integrity and central nervous system pathology. Raised protein suggests inflammation, infection (meningitis), demyelinating disease (multiple sclerosis), Guillain–Barré syndrome (often with normal cell count), tumor, hemorrhage, or spinal block. Very high elevations favor bacterial infection. Low CSF protein is uncommon but may indicate CSF leak or excessive drainage. Results are interpreted with cell counts, glucose and clinical findings.

A positive cerebrospinal fluid (CSF) test indicates infection, inflammation, bleeding, or malignant cells in the central nervous system. Physicians interpret specific findings (organism, cell type, protein/glucose changes), start targeted therapy (e.g., antibiotics, antivirals, steroids, oncologic treatment), perform cultures/PCR and imaging, monitor clinically, and may repeat CSF sampling or refer to neurology/infectious disease for ongoing management.

Protein electrophoresis helps detect abnormal patterns of serum or urine proteins, notably monoclonal gammopathies such as multiple myeloma, MGUS, and Waldenström macroglobulinemia. It also identifies light‑chain (Bence Jones) disease and amyloidosis, polyclonal gammopathies from chronic inflammation or liver disease, and hypogammaglobulinemia seen in immune deficiency. It is a screening tool prompting further specific testing.

High CSF protein indicates blood–brain barrier disruption or increased intrathecal protein production. It occurs with infections (bacterial/viral meningitis, encephalitis), inflammatory or demyelinating conditions (Guillain–Barré, multiple sclerosis), hemorrhage, tumors, or spinal block. Clinically, elevated CSF protein points to CNS pathology and typically prompts further testing (cell count, glucose, cultures, imaging) to identify the cause and guide treatment.

Oligoclonal bands in cerebrospinal fluid most classically indicate multiple sclerosis, but also appear in other inflammatory or infectious CNS conditions: neurosyphilis, neuroborreliosis (Lyme), viral encephalitides (HSV, VZV), HIV, neurosarcoidosis, CNS lupus and other autoimmune/paraneoplastic CNS diseases, subacute sclerosing panencephalitis and occasionally CNS lymphoma. Their presence supports intrathecal IgG synthesis but is not specific; clinical correlation and further testing are required.