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有关时间、上门服务和预约κ free light chain quantitation in serum; λ free light chain quantitation in serum; calculated κ:λ light chains ratio in serum
Values obtained with different assay methods should not be used interchangeably in serial testing. It is recommended that only one assay method be used consistently to monitor each patient's course of therapy. This procedure does not provide serial monitoring; it is intended for one-time use only. If serial monitoring is required, please use the serial monitoring number 121155 to order.
1 - 3 days
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
For more information, please view the literature below.
Interpretation of Results: Serum Free Light Chain Assays
Serum Free Light Chain Assays for Diagnosis and Monitoring of Myeloma
Serum
0.5 mL
0.2 mL
Red-top tube or gel-barrier tube
Sample should be allowed to clot and the serum separated as soon as possible 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.
Refrigerate; samples are stable for 21 days at 2°C to 8°C. For longer storage, freeze at -20°C.
Microbially-contaminated specimen; specimen containing particulate matter; lipemic or hemolyzed specimen
Free light chain (FLC) results should be considered under the following categories and investigated appropriately (κ = kappa free light chain; λ = lambda free light chain).
1. Normal samples: Serum κ, λ, and κ:λ are all within the normal ranges. If accompanying serum electrophoretic tests are normal, it is most unlikely that the patient has a monoclonal gammopathy.
2. Abnormal κ:λ ratios: Support the diagnosis of a monoclonal gammopathy and require an appropriate tissue biopsy. Borderline elevated κ:λ ratios occur with renal impairment and may require appropriate renal function tests.
3. Low concentrations of κ, λ, or both: Indicate bone marrow function impairment.
4. Elevated concentrations of both κ and λ with a normal κ:λ ratio: May be due to the following:
• Renal impairment (common)
• Overproduction of polyclonal FLCs from inflammatory conditions (common)
• Biclonal gammopathies of different FLC types (rare)
5. Elevated concentrations of both κ and λ with an abnormal κ:λ ratio: Suggest a combination of monoclonal gammopathy and renal impairment.
Kappa (κ) | Lambda (λ) | κ:λ Ratio | Interpretation |
---|---|---|---|
Key: BM = bone marrow; MG = monoclonal gammopathy; pIg = polyclonal immunoglobulin. | |||
Normal | Normal | Normal | Normal serum |
Low | Low | Normal | BM suppression without MG |
High | MG with BM suppression | ||
Low | |||
Normal | Normal | Normal serum or BM suppression | |
Low | MG with BM suppression | ||
High | Low | ||
Normal | Low | High | MG with BM suppression |
Normal | Normal serum or BM suppression | ||
Normal | High | MG with BM suppression | |
Low | |||
High | Normal | pIg increase or renal impairment | |
Low | MG without BM suppression | ||
High | Low | High | MG with BM suppression |
Normal | High | MG without BM suppression | |
Normal | pIg increase or renal impairment | ||
High | Normal | ||
High | MG with renal impairment | ||
Low |
Turbidimetric
• Free κ light chains: 3.3−19.4 mg/L
• Free λ light chains: 5.7−26.3 mg/L
• κ:λ free light chain ratio: 0.26−1.65
Immunoglobulin molecules consist of two identical heavy chains (α, δ, ε, γ, or μ) that define the immunoglobulin class and two identical light chains (κ or λ). 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 approximately 22.5 kilodaltons, in serum, κ free light chain (κ-FLC) exists primarily as a monomer and λ free light chain (λ-FLC) as a covalently-linked dimer with a molecular weight of approximately 45 kilodaltons. This will lead to a differential glomerular filtration rate for κ-FLC and λ-FLC and may explain the observed ratio of κ-FLC to λ-FLC of 0.625 in serum compared to the ratio of bound κ to λ 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.
Order Code | Order Code Name | Order Loinc | Result Code | Result Code Name | UofM | Result LOINC |
---|---|---|---|---|---|---|
121137 | Free K+L Lt Chains,Qn,S | 57778-3 | 121138 | Free Kappa Lt Chains,S | mg/L | 36916-5 |
121137 | Free K+L Lt Chains,Qn,S | 57778-3 | 121139 | Free Lambda Lt Chains,S | mg/L | 33944-0 |
121137 | Free K+L Lt Chains,Qn,S | 57778-3 | 121141 | Kappa/Lambda Ratio,S | 48378-4 |
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