IgG/Albumin Ratio, Spinal Fluid
Use
The IgG/Albumin Ratio test in cerebrospinal fluid (CSF) is significant for assessing the relative abundance of immunoglobulin G (IgG) compared to albumin. This ratio is crucial in diagnosing and managing central nervous system (CNS) inflammatory conditions, such as multiple sclerosis (MS), as it reflects the local synthesis of IgG within the CNS. An elevated IgG level in CSF compared to serum indicates intrathecal IgG production, which aids in diagnosing conditions like MS, neurosyphilis, and other inflammatory demyelinating diseases. The CSF IgG index and the IgG synthesis rate offer important insights into the disease state and progression.
Special Instructions
The test is primarily intended for situations where paired CSF and serum specimens are unavailable. It is critical to label the specimen as CSF and, if possible, submit CSF collected from vial number 2. The test setup days are from Monday to Friday, with results typically available within 1 to 3 days post specimen receipt. Properly refrigerate the specimen to maintain stability and avoid gross hemolysis as it may interfere with the results.
Limitations
The test can be confounded by other CNS inflammatory diseases since elevations in the index can occur in conditions like neurosyphilis and acute inflammatory polyradiculoneuropathy. Additionally, the CSF index is slightly less sensitive than CSF oligoclonal banding; however, combining both tests can improve diagnostic sensitivity. Improper specimen collection, handling, or mislabeling can adversely affect the test outcome and reliability.
FDA ApprovedNew York Approved
Methodology
Immunoassay (Nephelometry)
Biomarkers
LOINC Codes
- 2470-3
- 2464-6
- 1746-7
- 2470-3
Result Turnaround Time
1-3 days
Related Documents
For more information, please review the documents below
Specimen
Cerebrospinal Fluid
Volume
1 mL
Minimum Volume
0.5 mL
Container
Sterile vial
Collection Instructions
Submit CSF from collection vial number 2 (preferred, not required). Label specimen as CSF.
Causes for Rejection
Gross hemolysis: OK; Gross lipemia: OK; Gross icterus: OK
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 14 days |
| Refrigerated | 28 days |
| Frozen | 28 days |