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Test Code CASF IgG/Albumin Ratio, Spinal Fluid

Reporting Name

IgG/Albumin Ratio, CSF

Useful For

Assessment of cerebrospinal fluid (CSF) IgG/albumin ratio in the absence of a paired CSF and serum specimen

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Specimen Type

CSF


Ordering Guidance


The cerebrospinal fluid (CSF) index in which the CSF IgG/albumin ratio is compared to the serum IgG/albumin ratio aids in the diagnosis of individuals with multiple sclerosis. See SFIG / Cerebrospinal Fluid IgG Index Profile, Serum and Spinal Fluid.



Specimen Required


Specimen Type: Spinal fluid (CSF)

Container/Tube: Sterile vial

Specimen Volume: 1 mL

Collection Instructions:

1. Submit CSF from collection vial number 2 (preferred, not required).

2. Label specimen as CSF.


Specimen Minimum Volume

0.5 mL

Specimen Stability Information

Specimen Type Temperature Time
CSF Refrigerated (preferred) 28 days
  Frozen  28 days
  Ambient  14 days

Reference Values

CSF IgG: 0.0-8.1 mg/dL

CSF albumin: 0.0-27.0 mg/dL

CSF IgG/albumin: 0.00-0.21

Day(s) Performed

Monday through Friday

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

82042

82784

LOINC Code Information

Test ID Test Order Name Order LOINC Value
CASF IgG/Albumin Ratio, CSF 2470-3

 

Result ID Test Result Name Result LOINC Value
IGG_C IgG, CSF 2464-6
ALB_C Albumin, CSF 1746-7
AIGAC IgG/Albumin, CSF 2470-3

Method Description

The cerebrospinal fluid (CSF) IgG and albumin are determined by immunonephelometry on a Siemens Nephelometer II. In this assay, the light scattered by the antigen-antibody complexes are measured. The intensity of the measured scattered light is proportional to the amount of antigen-antibody complexes in the sample under certain conditions. If the antibody volume is kept constant, the signal behaves proportionally to the antigen volume. A reference curve is generated by a standard with a known antigen content on which the scattered light signals of the samples can be evaluated and calculated as an antigen concentration.

 

Antigen-antibody complexes are formed when a sample containing antigen, and the corresponding antiserum are put into a cuvette. A light beam is generated with a light emitting diode, which is transmitted through the cuvette. The light is scattered by the immuno-complexes that are present. Antigen and antibody are mixed in the initial measurement, but no complex is yet formed. An antigen-antibody complex is formed in the final measurement.

 

The result is calculated by subtracting the value of the final measurement from the initial measurement. The distribution of intensity of the scattered light depends on the ratio of the particle size of the antigen-antibody complexes to the radiated wavelength. CSF IgG and albumin, and CSF IgG/albumin ratios are reported.(Instruction manual: Siemens Nephelometer II Operations. Siemens, Inc; Version 2.4, 07/2019; Addendum to the Instruction Manual 2.3, 08/2017)

Report Available

1 to 3 days

Reject Due To

Gross hemolysis OK
Gross lipemia OK
Gross icterus OK

Method Name

Nephelometry

Secondary ID

8271