Interpretation of Results

Freelite is a sensitive, specific marker of kappa and lambda free light chains in serum.

Freelite Pocket Guide

This handy pocket sized guide contains relevant information on Freelite normal ranges and a useful chart to help interpret Freelite results. Also included is the latest information on MGUS risk stratification and the International uniform response criteria.

All this and only 13cm by 9cm, fitting perfectly into a shirt or coat pocket!

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Interpretation of serum free light chain results

Freelite results should be considered under the following categories and investigated appropriately.

1. Normal samples. Serum κ, λ and κ/λ ratio 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:

5. Elevated concentrations of both κ and λ with an abnormal κ/λ ratio.

Suggest a combination of monoclonal gammopathy and renal impairment.

Classification of monoclonal gammopathies according to serum kappa and lambda concentrations. Sectors refer to areas of the kappa / lambda plotter - see below.
Sector Kappa Lambda κ/λ Ratio Interpretation
1 Normal Normal Normal Normal Serum
2 Low Low Normal BM suppression without Monoclonal Gammopathy
3 High Monoclonal Gammopathy with BM Suppression
4 Low
5 Normal Normal Normal Serum with BM Suppression
6 Low Monoclonal Gammopathy with BM Suppression
7 High Low
8 Normal Low High
9 Normal Normal Serum with BM Suppression
10 Normal High Monoclonal Gammopathy with BM Suppression
11 Low
12 High Normal Polyclonal Ig increase or renal impairment
13 Low Monoclonal Gammopathy without BM Suppression
14 High Low High Monoclonal Gammopathy with BM Suppression
15 Normal High Monoclonal Gammopathy without BM Suppression
16 Normal Polyclonal Ig increase or renal impairment
17 High Normal
18 High Monoclonal Gammopathy with renal impairment
19 Low
BM = Bone marrow

Plot your patient's result using our Kappa/Lambda plotter

Serum reference ranges

The most extensive serum free light chain normal range study has been conducted at Mayo Clinic, USA, using Binding Site Freelite assays for the BN™II. In this study serum samples from 287 normal subjects aged from 20 to 90 years were assayed for free kappa and free lambda. The results from this trial are shown in the table below.

Reference Ranges for free kappa, free lambda and κ/λ ratio
Normal Adult Serum Mean Concentration Median Concentration 95 Percentile Range
Free Kappa 8.36 (mg/L) 7.30 (mg/L) 3.30-19.40 (mg/L)
Free Lambda 13.43 (mg/L) 12.40 (mg/L) 5.71-26.30 (mg/L)
  Mean Median Total Range
Kappa/Lambda ratio* 0.63 0.60 0.26-1.65

* In patients with renal failure you may wish to use the published renal reference range; κ/λ ratio 0.37 - 3.1 (instead of 0.26 - 1.65), Hutchison et al. BMC Nephrology 2008;9:11 doi:10.1186/1471-2369-9-11.

Kappa/Lambda ratio

The combination of individual concentrations of the free light chains and their ratio distinguishes a monoclonal increase from excess polyclonal production and renal dysfunction.
The ratio of kappa to lambda in serum is the opposite of that seen in urine, with kappa being lower than lambda. This is despite the fact that there are approximately twice as many kappa producing plasma cells as lambda producing cells.
The explanation for this is kappa molecules (25kDa), that are normally present in serum as monomers, are filtered through the kidney at approximately three times the rate of the lambda molecules (50kDa) which are present as dimers. So although the production rate of lambda in normal patients is lower than kappa, the serum concentration of lambda is actually higher, due to slower renal clearance. This also explains why, in the urine, the reverse is seen with kappa being present at approximately twice the level of lambda.

References

  1. Jerry A. Katzmann, Raynell J. Clark, Roshini S. Abraham, Sandra Bryant, James F. Lymp, Arthur R. Bradwell, and Robert A. Kyle.
    "Serum Reference Intervals And Diagnostic Ranges For Free κ And Free λ Immunoglobulin Light Chains: Relative Sensitivity For Detection Of Monoclonal Light Chains"
    Clin Chem 2002;48:9:1437-1444

    Reference: MKG194 Quantity:

  2. Freelite Pocket Guide (English International, Non-USA)

    Reference: MKG325.2 Quantity:

  3. Freelite Pocket Guide (Spanish)

    Reference: MKG365.2 Quantity:

  4. Freelite Pocket Guide (English, USA Only)

    Reference: MKG334.2 Quantity:

  5. Freelite Pocket Guide (French)

    Reference: MKG336.2 Quantity: