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HelpTest Code SFIG Cerebrospinal Fluid IgG Index Profile, Serum and Spinal Fluid
Specimen Required
Both serum and spinal fluid are required. Spinal fluid must be obtained within 7 days of serum collection.
Two individual serum samples are required.
Collection Container/Tube:
Preferred: Serum gel
Acceptable: Red top
Submission Container/Tube: 2 Plastic vials
Specimen Volume: 2 mL in 2 plastic vials, each vial containing 1 mL
Collection Instructions: Centrifuge and aliquot serum into 2 plastic vials within 2 hours of collection.
Specimen Type: Spinal fluid
Container/Tube: Sterile vial
Specimen Volume: 1 mL
Collection Instructions: Label specimen as SFINC.
Useful For
Aiding in the diagnosis of multiple sclerosis and other central nervous system inflammatory conditions
Profile Information
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| SFINC | IgG Index, CSF | No | Yes |
| SFIGS | IgG, S | No | Yes |
| ALBS1 | Albumin, S | Yes, (order ALB) | Yes |
Method Name
SFINC, SFIGS: Nephelometry
ALBS1: Photometric
Reporting Name
CSF IgG Index ProfileSpecimen Type
CSFSerum
Specimen Minimum Volume
Serum 1 mL in 2 plastic vials, each vial containing 0.5 mL
Spinal fluid: 0.5 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| CSF | Refrigerated (preferred) | 28 days | |
| Frozen | 28 days | ||
| Ambient | 14 days | ||
| Serum | Refrigerated (preferred) | 14 days | |
| Frozen | 28 days | ||
| Ambient | 7 days |
Reject Due To
| Criteria apply to serum specimens only. For CSF specimens, the criteria are not applicable. | |
| Gross hemolysis | Reject |
| Gross lipemia | Reject |
| Gross icterus | OK |
Clinical Information
Elevation of IgG in the cerebrospinal fluid (CSF) of patients with inflammatory diseases of the central nervous system (CNS) such as multiple sclerosis (MS), neurosyphilis, acute inflammatory polyradiculoneuropathy, subacute sclerosing panencephalitis may be due to local (intrathecal) synthesis of IgG.
The CSF index is the CSF IgG to CSF albumin ratio compared to the serum IgG to serum albumin ratio. The CSF index is, therefore, an indicator of the relative amount of CSF IgG compared to serum. Any increase in the index is a reflection of IgG production in the CNS. The IgG synthesis rate is a mathematical manipulation of the CSF index data and can also be used as a marker for CNS inflammatory diseases. The test is commonly ordered with oligoclonal banding or immunoglobulin kappa free light chains in CSF to aid in the diagnosis of demyelinating conditions.
Reference Values
CSF index: 0.00-0.85
CSF IgG: 0.0-8.1 mg/dL
CSF albumin: 0.0-27.0 mg/dL
Serum IgG
0-4 months: 100-334 mg/dL
5-8 months: 164-588 mg/dL
9-14 months: 246-904 mg/dL
15-23 months: 313-1,170 mg/dL
2-3 years: 295-1,156 mg/dL
4-6 years: 386-1,470 mg/dL
7-9 years: 462-1,682 mg/dL
10-12 years: 503-1,719 mg/dL
13-15 years: 509-1,580 mg/dL
16-17 years: 487-1,327 mg/dL
≥18 years: 767-1,590 mg/dL
Serum albumin
≥12 months: 3,500-5,000 mg/dL
Reference values have not been established for patients who are <12 months of age.
CSF IgG/albumin: 0.00-0.21
Serum IgG/albumin: 0.0-0.4
CSF IgG synthesis rate: 0-12 mg/24 hours
Day(s) Performed
Monday through Friday
Report Available
2 to 5 daysPerforming Laboratory
Mayo Clinic Laboratories in Rochester
Test Classification
This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.CPT Code Information
82040
82042
82784 x 2