Free Kappa and Lambda Light Chains Plus Ratio, Quantitative, Serum
| Free Kappa and Lambda Light Chains Plus Ratio, Quantitative, Serum | | | |
| Number | | 121137 |
| CPT | | 83883 (x2) |
Synonyms | | Free Light Chains, Quantitative, Serum ; Kappa Free
Light Chains, Quantitative, Serum ; Kappa/Lambda Free
Light Chains, Quantitative, Serum ; Kappa:Lambda Free
Light Chains Ratio, Quantitative, Serum ; Lambda Free
Light Chains, Quantitative, Serum ; Light Chains, Free
Kappa and Free Lambda, Quantitative, Serum ; FLC ; sFLC ;
FreeliteŽ |
| Test Includes | | Kappa free light chain quantitation in serum; lambda free light chain quantitation in serum; calculated kappa:lambda light chains ratio in serum |
| Specimen | | Serum |
| Volume | | 0.5 mL |
| Minimum Volume | | 0.2 mL |
| Container | | Red-top tube or gel-barrier tube |
| Collection | | Separate serum immediately after coagulation (30 minutes) to prevent hemolysis. To avoid delays in turnaround time when requesting multiple tests on frozen samples, please submit separate frozen specimens for each test requested. |
| Storage Instructions | | Stable at room temperature (25°C) for up to 7 days; longer when frozen at -20°C or lower. |
| Causes for Rejection | | Microbially-contaminated specimen; specimen containing particulate matter; lipemic or hemolyzed specimen |
| Reference Interval | | - Free kappa light chains: 3.30-19.40 mg/L
- Free lambda light chains: 5.71-26.30 mg/L
- Kappa:lambda free light chain ratio: 0.26-1.65
|
| Use | | Free light chain (FLC) results should be considered under
the following categories and investigated appropriately
("k" = Kappa free light chain, "L" = Lambda free light
chain):
- Normal samples: Serum k, L, and k/L
are all within the normal ranges. If accompanying serum
electrophoretic tests are normal, it is most unlikely that
the patient has a monoclonal gammopathy.
- Abnormal k/L ratios: Support the
diagnosis of a monoclonal gammopathy and require
an appropriate tissue biopsy. Borderline elevated k/L
ratios occur with renal impairment and may require
appropriate renal function tests.
- Low concentrations of k, L, or
both: Indicate bone marrow function impairment.
- Elevated concentrations of both k
and L with a normal k/L ratio: May be due to the
following:
- Renal impairment (common)
- Over-production of polyclonal FLCs from inflammatory
conditions (common)
- Biclonal gammopathies of different FLC types (rare)
- Elevated concentrations of both k and L
with an abnormal k/L ratio: Suggest a combination of
monoclonal gammopathy and renal impairment.
Interpretation Table of Serum Free Light Chain
Results
| Kappa (K)
| Lambda (L)
| K/L/Ratio | Interpretation |
| Normal | Normal | Normal | Normal Serum |
| Low |
Low |
Normal |
BM Suppression without MG1 |
| High |
Monoclonal
Gammopathy1 |
| Low |
| Normal |
Normal |
Normal serum1 |
| Low |
Monoclonal
Gammopathy1 |
| High |
Low |
| Normal |
Low |
High |
Monoclonal
Gammopathy1 |
| Normal |
Normal
serum1 |
| Normal |
High |
Monoclonal
Gammopathy1 |
| Low |
| High |
Normal |
plg or renal
impairment |
| Low |
Monoclonal
Gammopathy2 |
| High |
Low |
High |
Monoclonal
Gammopathy1 |
| Normal |
High |
Monoclonal
Gammopathy2 |
| Normal |
plg or renal
impairment |
| High |
Normal |
| High |
MG with
renal impairment |
| Low |
Key:
BM = Bone marrow
MG = Monoclonal Gammopathy
plg = Polyclonal Immunoglobulin
Footnotes:
(1) = With bone marrow (BM) suppression
(2) = Without bone marrow (BM) suppression |
| Methodology | | Nephelometry |
| Additional Information | | Immunoglobulin molecules consist of two identical heavy chains (alpha, delta, epsilon, gamma, or mu) which define the immunoglobulin class and two identical light chains (kappa or lambda). Each light chain is covalently linked to a heavy chain and the two heavy chains are linked covalently at the hinge region. In healthy individuals, the majority of light chains in serum exists in this form, bound to heavy chain; however, low levels of free light chain (flc) are found in serum of normal individuals due to the overproduction and secretion of flc by the plasma cells. While the molecular weight of both light chains is ~22.5 kilodaltons, in serum, kappa free light chain (kappa-flc) exists primarily as a monomer and lambda free light chain (lambda-flc) as a covalently-linked dimer with a molecular weight of ~45 kilodaltons. This will lead to a differential glomerular filtration rate for kappa-flc and lambda-flc and may explain the observed ratio of kappa-flc to lambda-flc of 0.625 in serum compared to the ratio of bound kappa to lambda of 2.0. Flc levels in urine are low. In a healthy kidney, the tubular cells selectively reabsorb all flc so their presence in urine is probably due to secretion into the urinary tract. Elevated serum levels of monoclonal flc are associated with malignant plasma cell proliferation (eg, multiple myeloma), primary amyloidosis, and light chain deposition disease. Raised serum levels of polyclonal flc may be associated with autoimmune diseases such as systemic lupus erythematosus. The appearance of higher levels of flc in urine may be indicative of kidney disease or malignant lymphoproliferative disease such as multiple myeloma. The monoclonal urinary flc associated with lymphoid malignancy is called a Bence Jones protein. |
| References | | Bradwell AR, Carr-Smith HD, Mead GP, et al, “Highly Sensitive, Automated Immunoassay for Immunoglobulin Free Light Chains in Serum and Urine,” Clin Chem, 2001, 47(4):673-80. Carr-Smith HD, Smith L, Mead GP, et al, “Development of Serum Free Light Chain Immunoassays for the Detection and Monitoring of Patients With Bence Jones Myeloma,” Proceedings of the VIIIth International Myeloma Workshop, Banff, Canada, May 2001, p176. Cole PW, Durie BGM, and Salmon SE, “Immunoquantitation of Free Light Chain Immunoglobulins: Application in Multiple Myeloma,” J Immunol Methods, 1978, 19(4):341-9. Drayson M, Tang LX, Drew R, et al, “Serum Free Light Chain Measurements for Identifying and Monitoring Patients With Nonsecretory Myeloma,” Blood, 2001, 97(9):2900-2. Katzmann JA, Clark RJ, Abraham RS, et al, “Serum Reference Intervals and Diagnostic Ranges for Free Kappa and Free Lambda Immunoglobulin Light Chains: Relative Sensitivity for Detection of Monoclonal Light Chains,” Clin Chem, 2002, 48(9):1437-44. Pascali E and Pezzoli A, “The Clinical Spectrum of Pure Bence-Jones Proteinuria. A Study of 66 Patients,” Cancer, 1988, 62(11):2408-15. Solling K, Solling J, and Romer FK, “Free Light Chains of Immunoglobulins in Serum From Patients With Rheumatoid Arthritis, Sarcoidosis, Chronic Infections and Pulmonary Cancer,” Acta Med Scand, 209(6):473-7. Tang LX, Showell P, Carr-Smith HD, et al, “Evaluation of F(ab′)(2)-Based Latex-Enhanced Nephelometric Reagents for Free Immunoglobulin Light Chains on the Behring Nephelometer™ II,” Clin Chem, 2000, 46:(6 Suppl):705, pA181. |
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