Test ID: SFIN
Cerebrospinal Fluid (CSF) IgG Index
Secondary ID 
A test code used for billing and in test definitions created prior to November 2011
NY State Approved Indicates the status of NY State approval and if the test is orderable for NY State clients.
Useful For Suggests clinical disorders or settings where the test may be helpful
As an aid in the diagnosis of multiple sclerosis
Profile Information A profile is a group of laboratory tests that are ordered and performed together under a single Mayo Test ID. Profile information lists the test performed, inclusive of the test fee, when a profile is ordered and includes reporting names and individual availability.
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| SFINC | IgG Index, CSF | No | Yes |
| SFINS | IgG, S | Yes, (order IGG) | Yes |
Method Name A short description of the method used to perform the test
Nephelometry
Reporting Name A shorter/abbreviated version of the Published Name for a test; an abbreviated test name
Aliases Lists additional common names for a test, as an aid in searching
Cerebrospinal Fluid (CSF) IgG Index
CSF (Cerebrospinal Fluid) Specific Protein IgG (Immunoglobulin G), Albumin
CSF Index
CSF, Specific Protein IgG, Albumin
IgG (Immunoglobulin G) Index
IgG (Immunoglobulin G) Spinal Fluid
IgG (Immunoglobulin G) Synthesis Rate
IgG Index
IgG Synthesis Rate
Synthesis Rate IgG
Specimen Type Describes the specimen type needed for testing
Serum
Specimen Required Defines the optimal specimen. This field describes the type of specimen required to perform the test and the preferred volume to complete testing. The volume allows automated processing, fastest throughput and, when indicated, repeat or reflex testing.
Serum and spinal fluid are required. Specimens must be obtained within 1 week of each other.
Specimen Type: Serum
Container/Tube: Red top or serum gel
Specimen Volume: 1 mL
Collection Instructions: Label specimen as serum.
Specimen Type: Spinal fluid
Container/Tube: Sterile vial
Specimen Volume: 1 mL
Collection Instructions: Label specimen as spinal fluid.
Specimen Minimum Volume Defines the amount of specimen required to perform an assay once, including instrument and container dead space. Submitting the minimum specimen volume makes it impossible to repeat the test or perform confirmatory or perform reflex testing. In some situations, a minimum specimen volume may result in a QNS (quantity not sufficient) result, requiring a second specimen to be collected.
Spinal Fluid: 0.5 mL
Reject Due To Identifies specimen types and conditions that may cause the specimen to be rejected
| Hemolysis | CSF: NA Serum: Mild OK; Gross OK |
| Lipemia | CSF: NA Serum: Mild OK; Gross reject |
| Icterus | CSF: NA Serum: Mild OK; Gross OK |
| Other | NA |
Specimen Stability Information Provides a description of the temperatures required to transport a specimen to the laboratory. Alternate acceptable temperature(s) are also included.
| Specimen Type | Temperature | Time |
|---|---|---|
| CSF | Refrigerated (preferred) | 14 days |
| Ambient | 14 days | |
| Frozen | 14 days | |
| Serum | Refrigerated (preferred) | 14 days |
| Ambient | 14 days | |
| Frozen | 14 days |
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Elevation of IgG levels in the cerebrospinal fluid (CSF) of patients with inflammatory diseases of the central nervous system (multiple sclerosis [MS], neurosyphilis, acute inflammatory polyradiculoneuropathy, subacute sclerosing panencephalitis) is due to local central nervous system (CNS) synthesis of IgG.
The 2 most commonly used diagnostic laboratory tests for MS are CSF index and oligoclonal banding. 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.
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
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
> or =18 years: 767-1,590 mg/dL
Serum albumin: 3,200-4,800 mg/dL
CSF IgG/albumin: 0.00-0.21
Serum IgG/albumin: 0.0-0.4
CSF IgG synthesis rate: 0-12 mg/24 hours
Interpretation Provides information to assist in interpretation of the test results
Cerebrospinal fluid (CSF) IgG index is positive (elevated) in approximately 80% of patients with multiple sclerosis (MS). Oligoclonal banding in CSF is also positive in approximately 80% of patients with MS. The use of CSF index plus oligoclonal banding has been reported to increase the sensitivity to over 90%.
The index is independent of the activity of the demyelinating process.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
The cerebrospinal fluid index can be elevated in other inflammatory demyelinating diseases such as neurosyphilis, acute inflammatory polyradiculoneuropathy, and subacute sclerosing panencephalitis.
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
1. Tourtellotte WW, Walsh MJ, Baumhefner RW, et al: 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;27:2011-2013
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;33:113-114
4. Swanson JW: Multiple Sclerosis: update in diagnosis and review of prognostic factors. Mayo Clin Proc 1989;64:577-586
5. Markowitz H, Kokmen E: Neurologic diseases and the cerebrospinal fluid immunoglobulin profile. Mayo Clin Proc 1983;58:273-274
Method Description Describes how the test is performed and provides a method-specific reference
The cerebrospinal fluid (CSF) and serum IgG and albumin are determined by immunonephelometry on a Siemens Nephelometer II. The CSF IgG index and synthesis rate are calculated and reported. In addition, the serum IgG and albumin, CSF IgG and albumin, and serum and CSF IgG/albumin ratios are reported.(Instruction manual: Siemens Nephelometer II Operations. Siemens, Inc., Newark, DE)
Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.
Monday through Saturday; 2 p.m.
Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.
Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Medical Laboratories until the release of the test result
Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Performing Laboratory Location The location of the laboratory that performs the test
Test Classification Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer's instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR), Investigation Use Only (IUO) product, or a Research Use Only (RUO) product.
CPT Code Information Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Medical Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
82040-Albumin, serum
82042-Albumin, spinal fluid
82784 x 2-IgG, serum and spinal fluid
LOINC® Code Information Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the result codes returned for this test or profile.
| Result ID | Reporting Name | LOINC Code |
|---|---|---|
| INDEX | IgG Index, CSF | 14117-6 |
| IGG_S | IgG, S | 2465-3 |
| ALB_S | Albumin, S | 1751-7 |
| IGG_C | IgG, CSF | 2464-6 |
| ALB_C | Albumin, CSF | 1746-7 |
| AIGAS | IgG/Albumin, S | 6782-7 |
| AIGAC | IgG/Albumin, CSF | 2470-3 |
| SRATE | Synthesis Rate, CSF | 14116-8 |
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