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Test Code KCSFP Immunoglobulin Kappa Free Light Chain, Spinal Fluid


Ordering Guidance


For evaluation of multiple sclerosis, the following are available:

-SFIG / Cerebrospinal Fluid IgG Index Profile, Serum and Spinal Fluid

-OLIG / Oligoclonal Banding, Serum and Spinal Fluid



Specimen Required


Only orderable as part of a profile. For more information see MSP3 / Multiple Sclerosis (MS) Profile, Serum and Spinal Fluid.

 

Specimen Type: Spinal fluid

Container/Tube: Sterile vial

Specimen Volume: 1 mL

Collection Instructions: Label specimen as spinal fluid.


Secondary ID

607839

Useful For

Diagnosis of multiple sclerosis and other demyelinating conditions

Method Name

Only orderable as part of a profile. For more information see MSP3 / Multiple Sclerosis (MS) Profile, Serum and Spinal Fluid.

 

Nephelometry

Reporting Name

Kappa Free Light Chain, CSF

Specimen Type

CSF

Specimen Minimum Volume

0.5 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
CSF Frozen (preferred) 28 days
  Refrigerated  72 hours
  Ambient  24 hours

Reject Due To

Gross hemolysis Reject
Gross icterus OK

Clinical Information

Multiple sclerosis (MS) is a chronic demyelinating disease of the central nervous system (CNS). The clinical diagnosis of MS is centered on each individual patient while applying diagnostic guidelines. Immunoglobulin free light chain (FLC) presence in cerebrospinal fluid (CSF) is an alternative for diagnosis of MS using nephelometry. Light chains are produced in excess during antibody formation and secreted from the plasma cells or plasma blasts. Quantitative FLC assays use antisera directed against epitopes that are exposed only when the light chains are free (unbound to heavy chain) in solution. FLC immunoassays can be used to specifically quantitate FLC even in the presence of large concentrations of polyclonal immunoglobulins.

 

Routine use of isoelectric focusing electrophoresis coupled with IgG-specific immunoblotting (IgG-IEF) identifies immunoglobulins specific to the CNS. This method is part of the diagnostic criteria used in cases of MS, ie, oligoclonal banding (OLIG). However, OLIG / Oligoclonal Banding, Serum and Spinal Fluid is a labor-intensive technique that includes subjective interpretation of IgG bands from paired CSF and serum.

 

This test, when considered positive at a concentration greater than or equal to 0.1000 mg/dL as a medical decision point, has a sensitivity of 70% with a specificity of 87%, which is comparable in terms of sensitivity and specificity to oligoclonal banding. The differences between this FLC test and the OLIG analysis are not statistically significant.

 

The MSP3 panel combines the ease of use and interpretation of the quantitative measurement of kappa-free light chains in CSF and allies it to the traditional interpretation of oligoclonal bands for optimized efficiency in laboratory testing for demyelinating diseases and improved test utilization.

Reference Values

Only orderable as part of a profile. For more information see MSP3 / Multiple Sclerosis (MS) Profile, Serum and Spinal Fluid.

 

Medical decision point: 0.1000 mg/dL

Interpretation

When result is greater than or equal to 0.1000 mg/dL, the kappa free light chain concentration measured in cerebrospinal fluid (CSF) is at or greater than the threshold associated with demyelinating disease. This is a positive result. These findings, however, are not specific for multiple sclerosis (MS) because CSF-specific immunoglobulin synthesis may also be detected in patients with other neurologic diseases (infectious, inflammatory, cerebrovascular, autoimmune, and paraneoplastic). Clinical correlation is recommended. Automatic reflexing to oligoclonal bands will occur.

 

When result is less than 0.0600 mg/dL, the kappa free light chain concentration measured in CSF is lower than the threshold associated with demyelinating disease. This is a negative result. Testing for oligoclonal banding is not performed. Clinical correlation is recommended.

 

When result is from 0.0600 to 0.0999 mg/dL, the kappa free light chain concentration measured in CSF is slightly elevated but not above the medical decision point of 0.1000 mg/dL associated with demyelinating disease. This is a borderline result. Reflexing to oligoclonal bands will be automatically performed and clinical correlation is recommended.

Method Description

In this nephelometric method, the light scattered onto the antigen-antibody complexes is measured. The intensity of the measured scattered light is proportional to the amount of antigen-antibody complexes in the sample under certain conditions.

 

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 (LED), which is transmitted through the cuvette. The light is scattered onto the immuno-complexes that are present. 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.(Instruction manual: Siemens Nephelometer II. Siemens, Inc; Version 2.3, 2008; Addendum to the Instruction Manual 2.3, 08/2017)

Day(s) Performed

Monday through Friday

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Test Classification

This test has been modified from the manufacturer's instructions. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information

83521

LOINC Code Information

Test ID Test Order Name Order LOINC Value
KCSFP Kappa Free Light Chain, CSF 48774-4

 

Result ID Test Result Name Result LOINC Value
KCSFP Kappa Free Light Chain, CSF 48774-4