Skip to content

Cerebrospinal Fluid Immunoglobulin G (IgG) Index by Electrophoresis

Published: August 9, 2026Updated: August 16, 2026

This test measures the ratio of immunoglobulin G (IgG) levels in your cerebrospinal fluid (CSF) compared to your blood. It helps assess whether IgG production is occurring in the central nervous system.

Quick summary

["This test helps identify possible immune-related conditions in your brain or spinal cord."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
42992-8
Short code
M pneumo IgG Titr CSF
Synonyms
M pneumo IgG Titr CSF
Category
chemistry
Sample
csf
Container
Sterile tube
Units
N/A
Ref low
8
Ref high
61
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
82977
SNOMED
3110003
Specimen volume
1-2 mL
Stability
Immediate analysis required, Refrigerated: 1h
Hemolysis max
200
TAT
4–24 hours
Order
routine

Why This Test Might Be Ordered

Your doctor may recommend this test if you have symptoms like headaches, neurological issues, or a history of conditions such as multiple sclerosis, meningitis, or other inflammatory diseases of the central nervous system. It can also be used to monitor certain immune responses in the brain.

What to Expect Before the Test

No special preparation is needed. You’ll have a small needle inserted into your lumbar spine to collect a small amount of CSF. This is usually done in a hospital or clinic setting and may cause mild discomfort.

What the Test Results Mean

The test compares IgG levels in your CSF to those in your blood. An elevated IgG index in CSF may suggest abnormal IgG production in the central nervous system, which can indicate conditions like multiple sclerosis, certain infections, or other immune disorders.

Common Conditions Monitored or Diagnosed

This test is often used to diagnose or monitor conditions such as multiple sclerosis, neuromyelitis optica, or other demyelinating diseases. It can also help identify inflammatory or infectious processes in the central nervous system.

Reference range

Adult males: 8-61 U/L; Adult females: 5-36 U/LN/A

Specimen: csf

No special preparation required. Avoid fatty meals before the test if possible.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

IgG Index (CSF)

Frequently asked questions

What does an elevated IgG index in CSF mean?
An elevated IgG index suggests that your immune system may be producing IgG antibodies in the central nervous system, which could indicate an underlying condition like multiple sclerosis or another immune-related disorder. Further testing and evaluation by your healthcare provider will be needed to determine the exact cause.
What if my IgG index is normal?
A normal IgG index means that your CSF IgG levels are within expected limits compared to your blood, suggesting no significant immune activity in the central nervous system at this time. However, this test alone cannot rule out all possible conditions, so your doctor may recommend additional tests or follow-up.
How often should I get this test?
The frequency of this test depends on your symptoms, medical history, and diagnosis. Your doctor will determine if repeated testing is needed to monitor progression or response to treatment for conditions like multiple sclerosis or other neurological disorders.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy