[Melanie]

Kappa FLC fluctuations in lambda light chain myeloma

by Melanie on Tue May 05, 2015 6:42 am

At diagnosis, my husband's light chains were 7700 last August. Original oncologist referred us to a myeloma specialist in December because of difficulty in getting his free light chains down. Currently his treatment regimen is Kyprolis (carfilzomib) (56 mg/m2), Cytoxan, and dexamethasone (20 mg on each day he goes for the Kyprolis infusion).

One thing that has always concerned me is how the kappa free light chains fluctuate while his lambda free light chains go down. At certain points during his treatment, the kappa was below normal. They finally went back into normal range, but they appear to be heading downward again. Is this cause for concern?

Below are his serum free light chain results since December.

Test Name Standard Range

Free kappa serum 3.30-19.40 mg/l
Free kappa/lambda ratio 0.260-1.650
Free lambda serum 5.71-26.30 mg/l

Date Kappa Ratio Lambda

Dec 10 2014 5.93 0.001 5496.40
Jan 07 2015 5.96 0.002 2721.60
Jan 31 2015 1.64 0.001 2849.20
Feb 07 2015 1.81 0.001 2589.00
Mar 02 2015 0.98 0.000 4949.00
Mar 04 2015 1.57 0.001 2279.40
Mar 27 2015 9.09 0.004 2030.20
Apr 03 2015 14.80 0.009 1728.60
Apr 29 2015 6.71 0.005 1434.70

[Dr. James Hoffman]

Re: Kappa FLC fluctuations in lambda light chain myeloma

by Dr. James Hoffman on Tue May 05, 2015 6:50 am

His myeloma cells secrete free lambda light chains. That is the important number to follow.

Because the medications suppress not only the abnormal plasma cells, there is some suppression of the 'healthy antibody' levels, and the free kappa light chain levels come down. You will be able to analyze how well the medicines are targeting the myeloma cells by watching the kappa-lambda ratio. As he responds to treatment further, the lambda will continue to drop, and the ratio will rise (since lambda is in the denominator).

I would ignore the free kappa light chain number.

Hope this clarifies.

[Melanie]

Re: Kappa FLC fluctuations in lambda light chain myeloma

by Melanie on Thu May 07, 2015 2:54 pm

Thank you so much for your response, Dr. Hoffman. Part of my concern is the kappa/lambda ratio. I was getting encouraged that the ratio was starting to finally head upwards, then discouraged when the ratio dropped again. So it is rather difficult for me not to look at the kappas.