[catkeson]

M-spike rising but kappa-lambda ratio not changing?

by catkeson on Sat Jan 26, 2019 10:37 pm

A family remember recently experienced a relapse 8 months after an autologous stem cell transplant. We are pretty upset about the relapse because he reached a complete response and was almost stringent complete in a bone marrow biopsy just two months before his relapse. We were expecting a long break before progression.

Anyway, the strange thing about his relapse is that the only his M protein is rising. His light chain ratio is only slightly abnormal (about 4.5) and it has remained steady as his M protein has continued to increase to 0.9 g/dl.

I have heard of myeloma that only produces light chains, but I have never heard of myeloma that only produces M protein.

Is there any explanation for why his light chains could be essentially normal while his M protein is increasing?

[Multibilly]

Re: M-spike rising but kappa-lambda ratio not changing?

by Multibilly on Sun Jan 27, 2019 12:07 pm

Hi Catkeson,

It's not a given that one's involved free light chain numbers will move in tandem with one's M-spike (M protein). This phenomenon can sometimes be explained by processes associated with "non­secretory" and "oligosectory" myeloma. If you read this article, you can get a better sense for how these processes work.

Also, keep in mind that changes in M-spikes can lag the changes that one may see in their free light chain numbers. This is because free light chains have a much shorter half life (about 6 hours) than do M-spikes (about 21 days for an IgG M-spike).

In my case as a smoldering patient, you can see in this post that my M-spike has bounced around in a channel over time, while my free light chain ratio and involved free light chain numbers have actually gone down over time.