Immunoglobulin A (IgA) Heavy and Light Chain (HLC) Pairs, κ and λ With Ratio

CPT: 83883(x2)
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Test Details

Synonyms

  • Hevylite IgA
  • HLC IgA
  • IgA κ:λ HLC Ratio

Use

For the quantitative measurement of human IgA heavy chain and light chain intact immunoglobulin in serum. The result can be used when monitoring previously diagnosed IgA multiple myeloma patients and is used in conjunction with other clinical and laboratory findings.

Heavy and light chain pair quantitation may be useful for:

1. Distinguishing between broadly migrating monoclonal proteins and restricted polyclonal immunoglobulin patterns on serum protein electrophoresis.

2. Quantitating monoclonal IgA proteins that are difficult to quantitate using serum protein electrophoresis alone.

3. Providing a more specific quantitation of the monoclonal protein than total IgA measurements alone.

Limitations

Decisions on patient evaluation and management must not be given on the basis of IgA κ, IgA λ, or IgA κ:IgG λ ratio measurements alone. Clinical history and other laboratory findings must be taken into account.

Heavy and light chain (HLC) quantitation should be used as a complementary method to serum protein electrophoresis.

The effect of therapeutic drugs on the measurement of IgA κ and IgA λ by this assay has not been evaluated.

Small increases in the concentrations of monoclonal IgA proteins may not result in an altered HLC pair ratio.

For initial detection of monoclonal proteins, see:

Immunofixation (IFE), Serum and Protein Electrophoresis, Serum [001495]

Immunofixation (IFE), Serum, Protein Electrophoresis (PE), Serum, and Quantitative Free κ and λ Light Chains (FLC) Plus Ratio, Serum [120256]

Immunofixation (IFE) and Protein Electrophoresis, 24-Hour Urine [003467]

Methodology

Nephelometry

Reference Interval

• IgA κ (g/L): 0.48−2.82

• IgA λ (g/L): 0.36−1.98

• IgA κ:IgA λ ratio: 0.80−2.04

An elevated IgA heavy and light chain (HLC) pair ratio suggests a clonal proliferation of an IgA κ clone of plasma cells.

A low IgA HLC pair ratio suggests a clonal proliferation of an IgA λ clone of plasma cells.

Additional Information

Elevated serum concentrations of monoclonal protein are indicative of an underlying abnormality, such as monoclonal gammopathy of undetermined significance (MGUS), multiple myeloma, and other lymphoproliferative disorders. International guidelines1 recommend serum protein electrophoresis (SPE) densitometry to be performed to quantify monoclonal proteins. However, monoclonal IgA proteins can often be obscured by other proteins in the β region of a SPE gel, making quantification inaccurate.

Nephelometry can be used in these instances to measure total IgA, but this will include nontumor immunoglobulin, and measurement of either IgA κ or IgA λ may give a more accurate representation of tumor production. Furthermore, measurement of both IgA κ and IgA λ, calculation of the IgA κ:IgA λ ratio and comparison with values found in normal subjects can give a more sensitive indication of clonality.2 Use of the IgA κ:IgA λ ratio will also compensate for any changes in plasma volume.

Specimen Requirements

Specimen

Serum

Volume

0.75 mL

Minimum Volume

0.5 mL

Container

Red-top tube or gel-barrier tube

Patient Preparation

Patient should be fasting for eight hours to avoid lipemic sample interference.

Collection

Separate serum immediately after coagulation (30 minutes) to prevent hemolysis.

Storage Instructions

Refrigerate.

Stability Requirements

Temperature

Period

Room temperature

14 days

Refrigerated

14 days

Frozen

14 days

Freeze/thaw cycles

Stable x3

Causes for Rejection

Microbially-contaminated specimen; specimen containing particulate matter; lipemic or hemolyzed specimen

Clinical Information

Footnotes

1. Smith A, Wisloff F, Samson D; UK Myeloma Forum; Nordic Myeloma Study Group; British Committee for Standards in Haematology. (2005) Guidelines on the diagnosis and management of multiple myeloma 2005. Br J Haematol. 2006 Feb; 132(4):410-451. 16412016
2. Bradwell AR, Harding S, Drayson M, Mead G. Novel nephelometric assays give a sensitive measure of residual disease in multiple myeloma (MM). Br J Haematol. 2008; 141(s1):39. Abstract 107.

LOINC® Map

Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
123540 IgA Heavy Light Chains(HLC), S 123531 IgA Kappa, S g/L 74864-0
123540 IgA Heavy Light Chains(HLC), S 123532 IgA Lambda, S g/L 74865-7
123540 IgA Heavy Light Chains(HLC), S 123533 IgA K/L HLC Ratio Ratio 74869-9

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