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Test ID 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
ALBS1 Albumin, S Yes, (order ALB) Yes

Method Name

SFINC, SFIGS: Nephelometry

ALBS1: Photometric

Reporting Name

CSF IgG Index Profile

Specimen Type


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

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


Cerebrospinal fluid (CSF) IgG synthesis rate indicates the rate of increase in the daily CSF production of IgG in milligrams per day. A result greater than 12 mg/24h is elevated.


A CSF index greater than 0.85 is elevated and indicative of increased synthesis of IgG.

Clinical Reference

1. Tourtellotte WW, Walsh MJ, Baumhefner RW, Staugaitis SM, Shapshak P: The current status of multiple sclerosis intra-blood-brain-barrier IgG synthesis. Ann NY Acad Sci. 1984;436:52-67

2. Bloomer LC, Bray PF: Relative value of three laboratory methods in the diagnosis of multiple sclerosis. Clin Chem. 1981 Dec;27(12):2011-2013

3. Hische EA, van der Helm HJ: Rate of synthesis of IgG within the blood-brain barrier and the IgG index compared in the diagnosis of multiple sclerosis. Clin Chem. 1987 Jan;33(1):113-114

4. Thompson AJ, Banwell BL, Barkhof F, et al: Diagnosis of multiple sclerosis: 2017 revisions of the McDonald criteria. Lancet Neurol. 2018 Feb;17(2):162-73. doi: 10.1016/S1474-4422(17)30470-2

5. Gurtner KM, Shosha E, Bryant SC, et al: CSF free light chain identification of demyelinating disease: comparison with oligoclonal banding and other CSF indexes. Clin Chem Lab Med. 2018 Jun 27;56(7):1071-1080. doi: 10.1515/cclm-2017-0901

6. Rifai N, Norvath AR, Wittwer CT, eds. Tietz Textbook of Clinical Chemistry and Molecular Diagnostics, 6th ed. Elsevier; 2018

Day(s) Performed

Monday through Friday

Report Available

2 to 5 days

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



82784 x 2

LOINC Code Information

Test ID Test Order Name Order LOINC Value
SFIG CSF IgG Index Profile 14116-8


Result ID Test Result Name Result LOINC Value
INDEX IgG Index, CSF 14117-6
ALB_S Albumin, S 1751-7
IGG_S IgG, S 2465-3
AIGAS IgG/Albumin, S 6782-7
IGG_C IgG, CSF 2464-6
ALB_C Albumin, CSF 1746-7
AIGAC IgG/Albumin, CSF 2470-3
SRATE Synthesis Rate, CSF 14116-8