[sandra256]

Free light chains & total light chains - difference?

by sandra256 on Tue Apr 07, 2015 12:03 pm

What is the difference between measurements of free light chains and the measurements of total light chains? Are both of these measurements through the blood or the urine?

[Dr. Jason Valent]

Re: Free light chains & total light chains - difference?

by Dr. Jason Valent on Tue Apr 07, 2015 1:16 pm

Excellent question. Free light chains can be measured in the serum and the urine, but ONLY the serum are important.

The free light chain test is done differently than tests that include total light chains.

The measurement of the "total" light chains are the light chains that are still attached with a heavy chain portion of the immunoglobulin. A fully intact immunoglobulin typically consists of two heavy chains and two light chains.

The free light chain test measures only light chains that are no longer attached to a heavy chain portion of the immunoglobulin. The free light chain test is particularly important as some patient's abnormal plasma cells only make the light chain portion of the immunoglobulin and the only way to detect this in the blood is with the serum free light chain test.

Hope this helps.

[sandra256]

Re: Free light chains & total light chains - difference?

by sandra256 on Tue Apr 07, 2015 1:40 pm

Thank you, Dr. Jason, for explaining the difference. It's a bit confusing.

Since the free light chains are the most important, then what would be the reason to test for total light chains?

Thank in advance.

[Dr. Jason Valent]

Re: Free light chains & total light chains - difference?

by Dr. Jason Valent on Wed Apr 08, 2015 3:09 pm

There is not much worth in the total light chains for disease monitoring. If a physician is screening for a plasma cell disorder, sometimes the total levels help but even then, there is limited utility.

[lion13]

Re: Free light chains & total light chains - difference?

by lion13 on Wed Jul 15, 2015 1:45 am

Are some reference values for total light chains within normality? Thanks.

[Cheryl G]

Re: Free light chains & total light chains - difference?

by Cheryl G on Wed Jul 15, 2015 9:46 am

Reference ranges can vary from lab to lab, so you really want to look on your test results to see what they list as the reference range for your specific results.

That said, Dr. Shain mentions the reference range for total light chains, for tests conducted by Quest Laboraties, in this posting:

https://myelomabeacon.org/forum/free-light-chains-reference-values-units-t3225.html#p18244

They're as follows:

Reference Range(s)

Kappa: 74-295 mg/dL
Lambda: 32-156 mg/dL
Kappa/Lambda Ratio: 1.3-2.7