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Method Update for Serum Free Light Chains, IgG Subclasses, Immunoglobulins IgG, IgA, and IgM
Due to an impending discontinuation of test reagents by our current vendor, the Department of Pathology & Laboratory Medicine will transition certain special chemistry tests (serum free light chains, IgG subclasses, and immunoglobulins IgA, IgM, IgG) to a new instrument platform, the Optilite® (Binding Site).

Values for serum free light chains with the new method may display some discordance with the previous method in certain cases. The bias for kappa free light chains, or the kappa/lambda ratio may be more pronounced in patients with a very elevated kappa/lambda ratio. The laboratory will provide rebaselining for individual patients for serum free light chains upon request if clinically indicated. Values for all other tests measured by new methods compare well with previous methods.

Reference intervals will be updated in accordance with manufacturer recommendations. The adult serum reference intervals were verified in 24 adult blood donors. Pediatric ranges for Immunoglobulin IgA, IgG, and IgG Subclasses will also be updated in accordance with manufacturer recommendations.
Test Name Test Code Previous Adult Reference Interval New Adult Reference Interval
Kappa, Serum free light chains KAPLA 3.30-19.4 mg/L 3.30-19.4 mg/L
Lambda, Serum free light chains KAPLA 5.71-26.3 mg/L 5.71-26.3 mg/L
Kappa/Lambda Ratio KAPLA 0.26-1.65 0.26-1.65
Immunoglobulin IgG IGG 694-1618 mg/dL 610-1616 mg/dL
Immunoglobulin IgM IGM 65-263 mg/dL 35-242 mg/dL
Immunoglobulin IgA IGA 68-378 mg/dL 84-499 mg/dL
Immunoglobulin IgG Subclass 1 IGGSUB 2396-10835 mg/L 3824-9286 mg/L
Immunoglobulin IgG Subclass 2 IGGSUB 1235-5487 mg/L 2418-7003 mg/L
Immunoglobulin IgG Subclass 3 IGGSUB 276-1344 mg/L 218-1761 mg/L
Immunoglobulin IgG Subclass 4 IGGSUB, IGG4 69-888 mg/L 52-1250 mg/L
Immunoglobulin IgG, Spinal fluid IGGCSF 0.5-5.9 mg/dL 0.5-5.9 mg/dL

Effective date: March 27, 2019

Specimen requirement and testing information:

Specimen: Serum

Test methodology: Turbidimetric

Minimum Stability† (after separation from cells):
Ambient: 2 hours
Refrigerated: 8 days
Frozen: 1 month

†Some tests may have extended stability beyond stated minimum limits. See directory for details.

Turnaround time (TAT):
Routine: 1-3 days
Set Up Days: M, W, F

Rejection criteria:
Samples containing particulate matter, and lipemic or hemolyzed specimens. Specimens that exceed stated stability, unlabeled/mislabeled/mismatched specimens, specimens submitted in leaking containers, or specimens received with insufficient amounts for testing.

A summary of all tests offered by our laboratory services can be found here:


Bridgit O. Crews, PhD, DABCC
Clinical Chemistry & Toxicology

Edwin S. Monuki, MD, PhD
Department of Pathology & Laboratory Medicine
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