Thank you, Cheryl G
I do know that the kappa/lambda ratio is the kappa flc number divided by the lambda flc number, but it is clearly worth restating that.
What puzzles me is how, if the kappa, lambda flc numbers fall into the respective normal ranges, can the ratio be abnormal?
Answering this question in detail probably comes down to knowing how the normal range for the ratio is established. But I have not been able to find that anywhere.
Intuitively, it seems to me that if the component flc numbers for kappa and gamma light chains include normal light chains as well as those produced by the myeloma cells (as they apparently do) and the ratio can somehow be interpreted in a way that cancels this factor out, then it would make sense for it to give a better measure of the monoclonal flc's than do the kappa and lambda flc numbers by themselves.
And this 'better picture" would also help explain why the ratio itself must be normal for one to have attained a Stringent Complete Response. Even if the kappa and lambda numbers are normal.
So I am curious about the underlying math having to do with the interpretation of the ratio, beyond its simple derivation.
Hi Nancy Shamanna and mrozdav,
Those are good points; thanks for adding them.
Forums
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MrPotatohead - Name: MrPotatohead
- Who do you know with myeloma?: Me
- When were you/they diagnosed?: March, 2015
- Age at diagnosis: 65
Re: Normal kappa & lambda FLC levels, but high ratio
Hi MrPotatohead,
It sounds like you need a more technical explanation, so I'll take a crack at it.
In people who do not have a monoclonal gammopathy -- or who have had one, but are now in a deep remission -- the kappa and lambda free light chain levels go up and down together. They are highly correlated (have a high covariance).
In these people, you do not often see a high -- but within range -- kappa level at the same time you see a low -- but within range -- lambda level. You either see high kappa AND lambda levels, or you see low kappa and lambda levels.
Because this is the case, the "normal" range for the kappa/lambda ratio is much smaller than would be the case if the kappa and lambda levels varied independently of one another in healthy people.
Hope that helps explain things a bit.
It sounds like you need a more technical explanation, so I'll take a crack at it.
In people who do not have a monoclonal gammopathy -- or who have had one, but are now in a deep remission -- the kappa and lambda free light chain levels go up and down together. They are highly correlated (have a high covariance).
In these people, you do not often see a high -- but within range -- kappa level at the same time you see a low -- but within range -- lambda level. You either see high kappa AND lambda levels, or you see low kappa and lambda levels.
Because this is the case, the "normal" range for the kappa/lambda ratio is much smaller than would be the case if the kappa and lambda levels varied independently of one another in healthy people.
Hope that helps explain things a bit.
Re: Normal kappa & lambda FLC levels, but high ratio
Dear Cheryl G,
That does clear things up for me quite a bit! Thank you so much.
It would make sense for factors that are normally correlated to be jointly evaluated using a comparative computation, like a ratio. The lack of correlation, within a given range, could then be a measure of abnormality.
I appreciate your help very much.
That does clear things up for me quite a bit! Thank you so much.
It would make sense for factors that are normally correlated to be jointly evaluated using a comparative computation, like a ratio. The lack of correlation, within a given range, could then be a measure of abnormality.
I appreciate your help very much.
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MrPotatohead - Name: MrPotatohead
- Who do you know with myeloma?: Me
- When were you/they diagnosed?: March, 2015
- Age at diagnosis: 65
Re: Normal kappa & lambda FLC levels, but high ratio
Hi folks,
I seem to have somewhat normal lambda and kappa numbers, but my free light chain ratio has gone from 35 to 65 and has been climbing for the last 6 months along with increasing levels of bone pain in my ribs, lower back, and hip. At first I thought it was just muscle loss / weakness / fatigue from taking dexamethasone for 3 years, but now it is apparent to me, that I’ve gone into a relapse after completing 20 cycles (about 1.5 years) of Ninlaro with dexamethasone.
This week, my oncologist is changing my treatment to Darzalex, Velcade, and dexamethasone,
so I expect the bone pain will subside in a month or so and I will be able to stand and walk again with less pain.
Bob D
I seem to have somewhat normal lambda and kappa numbers, but my free light chain ratio has gone from 35 to 65 and has been climbing for the last 6 months along with increasing levels of bone pain in my ribs, lower back, and hip. At first I thought it was just muscle loss / weakness / fatigue from taking dexamethasone for 3 years, but now it is apparent to me, that I’ve gone into a relapse after completing 20 cycles (about 1.5 years) of Ninlaro with dexamethasone.
This week, my oncologist is changing my treatment to Darzalex, Velcade, and dexamethasone,
so I expect the bone pain will subside in a month or so and I will be able to stand and walk again with less pain.
Bob D
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Bob_D - Name: Bob_D
- Who do you know with myeloma?: me
- When were you/they diagnosed?: March 2015
- Age at diagnosis: 59
14 posts
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