Can someone please confirm that my understanding is correct, or tell me what I've got wrong?
Assume a completely normal serum protein electrophoresis; no M spike detected.
Assume also a a completely normal serum free light chain assay; kappa and lambda normal, both in quantity and in ratio.
Am I right to say that urine protein electrophoresis (UPEP), which looks for the same light chains as the serum free light chain (sFLC) assay, but is less sensitive, cannot (absent lab error on either the sFLC or the UPEP) detect anything that the sFLC does / has not? Is that not why some myeloma specialists have dispensed with UPEP entirely in favor of SPEP + sFLC as the initial screening panel, and why sFLC is now generally preferred to UPEP to track progression of light chain and oligosecretory myeloma?
I think there may be an exception to the above for light chain amyloidosis (which maybe someone can explain to me), but do I otherwise have this straight?
Thanks for any replies.
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Re: Serum free light chain test vs. urine electrophoresis
Hi ThePride,
You would think that your understanding of the situation would be correct. However, I've come across at least a couple of posts on this forum where a Bence-Jones M-spike is detected on a 24 hour UPEP, yet the serum immunofixation and serum free light chain values have come back as normal. I've never understood how this can be possible.
You would think that your understanding of the situation would be correct. However, I've come across at least a couple of posts on this forum where a Bence-Jones M-spike is detected on a 24 hour UPEP, yet the serum immunofixation and serum free light chain values have come back as normal. I've never understood how this can be possible.
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Multibilly - Name: Multibilly
- Who do you know with myeloma?: Me
- When were you/they diagnosed?: Smoldering, Nov, 2012
Re: Serum free light chain test vs. urine electrophoresis
Not the response I was hoping for (as you probably inferred!), but appreciated regardless. Thanks.
Re: Serum free light chain test vs. urine electrophoresis
Maybe you might want to factor in Dr. Hoffman's advice provided in this post?
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Multibilly - Name: Multibilly
- Who do you know with myeloma?: Me
- When were you/they diagnosed?: Smoldering, Nov, 2012
Re: Serum free light chain test vs. urine electrophoresis
After your first comment I found some of the posts you referenced, but missed this one. So thank you.
As it happens, I don't yet have the UPEP results. To make a long story short, this is the second time I've been through testing for "something" on the MGUS-myeloma spectrum. The first time, performed at a major cancer center with a myeloma department, ended with the conclusion that "perhaps" or "perhaps not" there was something going on, but if so, it was still so nascent that it wouldn't even warrant an MGUS diagnosis. I won't bore you with all the testing, except to say that the only thing that even raised the "perhaps" part of the above was mildly elevated creatinine (1.4), slight anemia (12.9), and a UPEP that showed "a slight restriction in the gamma region possibly indicating the presence of a monoclonal protein." Everything else, including serum free light chain results, A-OK.
This time, my GP decided to screen (good for her; very thorough) because of the return of the very slight and unexplained anemia (now 13.4; have had more GI workups to look for bleeds than I can count, etc., without any explanatory finding); creatinine has actually improved and is stable. She told me she ordered SPEP and UPEP, but it turns out (as I indicated in my original post) that the SPEP order also included the free light chain assay. I was thus surprised that she considered it important to wait for UPEP to rule out, given the "clean" SPEP and sFLC results, but the posts you've pointed to, my own prior history, and the fact that my father developed active myeloma (though very late in life, and he died of something else) of course raise the possibility that there is lurking MGUS (or another plasma cell disorder) that is still just not producing enough monoclonal protein to be reliably detected / quantified, or that light chain amyloidosis (which I understand may be suggested by urine albuminaria even where sFLC is normal and UPEP is ambiguous or inconclusive) is a possibility, although an exceedingly unlikely one given that I have no amyloidosis-like symptoms and the overall rarity of the disease.
Still, as you know much better than I, it's hard to be completely rational and not worry in these situations. So I'll wait, and that's that.
Like many others who visit these forums, I value your posts, responsiveness, and input. Thank you.
As it happens, I don't yet have the UPEP results. To make a long story short, this is the second time I've been through testing for "something" on the MGUS-myeloma spectrum. The first time, performed at a major cancer center with a myeloma department, ended with the conclusion that "perhaps" or "perhaps not" there was something going on, but if so, it was still so nascent that it wouldn't even warrant an MGUS diagnosis. I won't bore you with all the testing, except to say that the only thing that even raised the "perhaps" part of the above was mildly elevated creatinine (1.4), slight anemia (12.9), and a UPEP that showed "a slight restriction in the gamma region possibly indicating the presence of a monoclonal protein." Everything else, including serum free light chain results, A-OK.
This time, my GP decided to screen (good for her; very thorough) because of the return of the very slight and unexplained anemia (now 13.4; have had more GI workups to look for bleeds than I can count, etc., without any explanatory finding); creatinine has actually improved and is stable. She told me she ordered SPEP and UPEP, but it turns out (as I indicated in my original post) that the SPEP order also included the free light chain assay. I was thus surprised that she considered it important to wait for UPEP to rule out, given the "clean" SPEP and sFLC results, but the posts you've pointed to, my own prior history, and the fact that my father developed active myeloma (though very late in life, and he died of something else) of course raise the possibility that there is lurking MGUS (or another plasma cell disorder) that is still just not producing enough monoclonal protein to be reliably detected / quantified, or that light chain amyloidosis (which I understand may be suggested by urine albuminaria even where sFLC is normal and UPEP is ambiguous or inconclusive) is a possibility, although an exceedingly unlikely one given that I have no amyloidosis-like symptoms and the overall rarity of the disease.
Still, as you know much better than I, it's hard to be completely rational and not worry in these situations. So I'll wait, and that's that.
Like many others who visit these forums, I value your posts, responsiveness, and input. Thank you.
5 posts
• Page 1 of 1