Dear all in this forum.
I travel for business. My travel location serum protein electrophoresis (SPEP) is showing no M-spike since sixth and seventh cycle. But my U.S. lab gave a reading of 0.7 g/dL.
I have a U.S. lab doing all SPEP and immunofixation electrophoresis (IFE) tests plus free light chain and 24-hour urine every time. But when I travel, I have primarily CBC and SPEP.
If SPEP gives no value for M-spike, IFE is the only way to, the best of my knowledge, detect myeloma - although it is subjective.
My question to the group is: How accurate is the M-spike result from the SPEP once the reading goes down below 1 g/dL (10 g/L)?
Forums
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MMFeb16,15 - Who do you know with myeloma?: Self
- When were you/they diagnosed?: February 16, 2015
- Age at diagnosis: 66
Re: How accurate are M-spike readings less than 1?
MMFeb16,
Scientifically speaking, there is a reason the result is reported with just one decimal position. Whether all labs enforce the standard may be left to the regulatory or other organization that standardizes lab results.
As for your result of 0.7, you can assume you were closer to 0.7 than 0.6 or 0.8. If you tested your blood on a more sensitive test that reported two decimal places, you could expect a report of 0.65 to 0.75 on the same blood sample. Of course there are different lab tests performed on equipment from different equipment manufactures and most must be periodically calibrated by operators, which in itself can lead to inaccuracies. Then there is the case of a flat-out outlier result that is in left field.
I'd feel confident your result is 0.7 from an accredited lab.
Scientifically speaking, there is a reason the result is reported with just one decimal position. Whether all labs enforce the standard may be left to the regulatory or other organization that standardizes lab results.
As for your result of 0.7, you can assume you were closer to 0.7 than 0.6 or 0.8. If you tested your blood on a more sensitive test that reported two decimal places, you could expect a report of 0.65 to 0.75 on the same blood sample. Of course there are different lab tests performed on equipment from different equipment manufactures and most must be periodically calibrated by operators, which in itself can lead to inaccuracies. Then there is the case of a flat-out outlier result that is in left field.
I'd feel confident your result is 0.7 from an accredited lab.
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blueblood - Name: Craig
- Who do you know with myeloma?: Myself
- When were you/they diagnosed?: March 2014
- Age at diagnosis: 54
Re: How accurate are M-spike readings less than 1?
My personal experience is that SPEP measurement results can vary widely between accredited labs, regardless of the magnitude of the M-spike. I have been getting an SPEP performed at both Quest Diagnostics and Labcorp every two months since August, 2015. Each time, my test sample has been drawn less than one week apart between the two labs. However, the difference in my M-spike readings is remarkable.
M-spike (g/dL)
Date Quest Labcorp % Difference
08/2015 3.20 2.10 52%
10/2014 2.90 2.40 21%
12/2015 3.20 2.40 33%
M-spike (g/dL)
Date Quest Labcorp % Difference
08/2015 3.20 2.10 52%
10/2014 2.90 2.40 21%
12/2015 3.20 2.40 33%
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Multibilly - Name: Multibilly
- Who do you know with myeloma?: Me
- When were you/they diagnosed?: Smoldering, Nov, 2012
Re: How accurate are M-spike readings less than 1?
Hi Multibilly,
Wow! Those are big differences! That's another example of why looking at the trend is more important than looking at one number in isolation.
Just curious - do any other measurements for other lab tests that you get from Quest and Labcorp also differ a lot?
Mike
Wow! Those are big differences! That's another example of why looking at the trend is more important than looking at one number in isolation.
Just curious - do any other measurements for other lab tests that you get from Quest and Labcorp also differ a lot?
Mike
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mikeb - Name: mikeb
- Who do you know with myeloma?: self
- When were you/they diagnosed?: 2009 (MGUS at that time)
- Age at diagnosis: 55
Re: How accurate are M-spike readings less than 1?
Hi Mike,
I only get duplicate IgG and SPEP tests done at Quest, so I can't really answer that question.
What prompted me to get a second set of lab tests from a different lab in the first place was when my M-spike from Quest went up to 3.2 g/dL in August 2015 from a previous reading of 2.6 g/dL two months earlier. I simply didn't believe that jump and my Labcorp test results proved my suspicion. When I got my next Quest results in December, the Quest M-spike was higher than my involved IgG immunoglobulin level (which is impossible). So, my faith in Quest's testing accuracy was pretty much ruined at that point. Now I just get a complete set of Labcorp tests and an IgG and SPEP test from Quest and just look at the trends ... and put my faith in Labcorp's absolute numbers.
Since you asked, I will probably get a duplicate set of all the tests from Quest next time I get tested (my Quest labs don't cost me anything on my insurance plan, but my Labcorp tests do incur out of pocket costs). I will let you know what I find out. My hematologist was going to raise these lab measurement issues with Quest, but I don't think he has had the time to do so yet.
I only get duplicate IgG and SPEP tests done at Quest, so I can't really answer that question.
What prompted me to get a second set of lab tests from a different lab in the first place was when my M-spike from Quest went up to 3.2 g/dL in August 2015 from a previous reading of 2.6 g/dL two months earlier. I simply didn't believe that jump and my Labcorp test results proved my suspicion. When I got my next Quest results in December, the Quest M-spike was higher than my involved IgG immunoglobulin level (which is impossible). So, my faith in Quest's testing accuracy was pretty much ruined at that point. Now I just get a complete set of Labcorp tests and an IgG and SPEP test from Quest and just look at the trends ... and put my faith in Labcorp's absolute numbers.
Since you asked, I will probably get a duplicate set of all the tests from Quest next time I get tested (my Quest labs don't cost me anything on my insurance plan, but my Labcorp tests do incur out of pocket costs). I will let you know what I find out. My hematologist was going to raise these lab measurement issues with Quest, but I don't think he has had the time to do so yet.
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Multibilly - Name: Multibilly
- Who do you know with myeloma?: Me
- When were you/they diagnosed?: Smoldering, Nov, 2012
Re: How accurate are M-spike readings less than 1?
This is an issue that I have kicked around in my mind quite a bit. The lack of faith in the precision of these readings was reinforced for me when I was discussing with my oncologist the relatively high level of my presumably secondary MGUS M-spike. In the course of relating how he had never seen a secondary MGUS M-spike as high as mine, he mentioned that the in-house lab had modified its testing a few years back, which now results in consistently higher readings.
It does make you acutely aware that we should not rely on just a single test result to make important treatment decisions.
It does make you acutely aware that we should not rely on just a single test result to make important treatment decisions.
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goldmine848 - Name: Andrew
- When were you/they diagnosed?: June 2013
- Age at diagnosis: 60
Re: How accurate are M-spike readings less than 1?
For me the, the serum free light chain (sFLC) test is the one that I watch the closest. My oncologist changed labs a year ago and immediately I noticed a difference. I have always had a very low M spike of 0.3 g/dL or lower, so I don't put much stock in that test. However, when the sFLC starts showing a consistent trend, that gets my attention.
The trend over the course of a number of tests is what should be focused on. If you are using two labs and you see a consistent trend in both labs, then you can be pretty confident that something good or bad is occurring. I never put stock in any single test. These tests are, in large, a count that are aggregate-type measurements. They are not like a precise engineering measurement.
The trend over the course of a number of tests is what should be focused on. If you are using two labs and you see a consistent trend in both labs, then you can be pretty confident that something good or bad is occurring. I never put stock in any single test. These tests are, in large, a count that are aggregate-type measurements. They are not like a precise engineering measurement.
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Ron Harvot - Name: Ron Harvot
- Who do you know with myeloma?: Myself
- When were you/they diagnosed?: Feb 2009
- Age at diagnosis: 56
Re: How accurate are M-spike readings less than 1?
Blueblood and other in this forum:
I had three labs in the beginning. Two in the USA and one overseas where I travel most of the time. All three gives different M spike results. Now I have two labs - one where my main hematologist is, and the other where my overseas hematologist is. Always the U.S. lab is 0.5 higher compared to the overseas lab.
I am still overseas. Today I had my CBP and SEP result after ten cycles of Revlimid and dex. For the first time, all my blood parameters are normal. No M spike. My hematologist ordered for immunoelectrophoresis and light chain after eleventh cycle.
I read somewhere that M spike below one is not as reliable as above one.
Thank you.
I had three labs in the beginning. Two in the USA and one overseas where I travel most of the time. All three gives different M spike results. Now I have two labs - one where my main hematologist is, and the other where my overseas hematologist is. Always the U.S. lab is 0.5 higher compared to the overseas lab.
I am still overseas. Today I had my CBP and SEP result after ten cycles of Revlimid and dex. For the first time, all my blood parameters are normal. No M spike. My hematologist ordered for immunoelectrophoresis and light chain after eleventh cycle.
I read somewhere that M spike below one is not as reliable as above one.
Thank you.
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MMFeb16,15 - Who do you know with myeloma?: Self
- When were you/they diagnosed?: February 16, 2015
- Age at diagnosis: 66
Re: How accurate are M-spike readings less than 1?
I think people may be getting confused because the 1 g/dL cutoff is one of the criteria used by myeloma specialists to define what is known as "measurable disease".
Historically, myeloma specialists have calculated response rates to treatment only for patients who have had "measurable disease", which has been defined using these criteria:
My point is that I don't think anything magic happens when M-spike (or free light chain) levels get down below their "measurable" cutoff. Particularly in the case of the M-spike test, the test still has the same variability that it has when the M-spike levels are higher.
Yes, that variability matters more, in some ways, when M-spike levels are low. Accuracy that is equal to, say, plus or minus 0.3 g/dL is a "big" number when the M-spike reading is 0.5 g/dL. But the plus-or-minus amount isn't really different than what it is when the M-spike readings are higher.
I'm think that, if an M-spike comes back as 0.4 g/dL from the same lab which, a few months ago, said the M-spike was 2.4 g/dL, then the 0.4 estimate is just as accurate as the 2.4 estimate, in terms of the plus-or-minus "X" g/dL amount (whatever X may be).
Still, as everyone says, look at trends and at other lab results to make sure a given lab result makes sense. Also, things can definitely be different if you change labs. (Great info from Multibilly above, by the way. Thanks for that.)
For those who are interested, the cutoffs I listed up above for measurable disease are from this table, which comes from this discussion of myeloma response rate definitions:
BGM Durie et al, "International uniform response criteria for multiple myeloma," Leukemia, July 2006 (full text of article)
Historically, myeloma specialists have calculated response rates to treatment only for patients who have had "measurable disease", which has been defined using these criteria:
- Serum M-protein greater than or equal to 1 g/dl (10 g/L)
- Urine M-protein greater than or equal to 200 mg/24 h
- Involved serum free light chain level greater than or equal to 10 mg/dl (100 mg/L)
My point is that I don't think anything magic happens when M-spike (or free light chain) levels get down below their "measurable" cutoff. Particularly in the case of the M-spike test, the test still has the same variability that it has when the M-spike levels are higher.
Yes, that variability matters more, in some ways, when M-spike levels are low. Accuracy that is equal to, say, plus or minus 0.3 g/dL is a "big" number when the M-spike reading is 0.5 g/dL. But the plus-or-minus amount isn't really different than what it is when the M-spike readings are higher.
I'm think that, if an M-spike comes back as 0.4 g/dL from the same lab which, a few months ago, said the M-spike was 2.4 g/dL, then the 0.4 estimate is just as accurate as the 2.4 estimate, in terms of the plus-or-minus "X" g/dL amount (whatever X may be).
Still, as everyone says, look at trends and at other lab results to make sure a given lab result makes sense. Also, things can definitely be different if you change labs. (Great info from Multibilly above, by the way. Thanks for that.)
For those who are interested, the cutoffs I listed up above for measurable disease are from this table, which comes from this discussion of myeloma response rate definitions:
BGM Durie et al, "International uniform response criteria for multiple myeloma," Leukemia, July 2006 (full text of article)
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JimNY
Re: How accurate are M-spike readings less than 1?
The trends at both the labs are consistent in my case. A twenty percent difference in M-spike value is also pretty much consistent.
I am giving more weight to main hematologist and main lab in the USA. And after no M-spike and a reading of 0.7 at the USA lab, I am also giving more attention to light chain and Immunoelectrophoresis test result.
Any suggestion?
I am giving more weight to main hematologist and main lab in the USA. And after no M-spike and a reading of 0.7 at the USA lab, I am also giving more attention to light chain and Immunoelectrophoresis test result.
Any suggestion?
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MMFeb16,15 - Who do you know with myeloma?: Self
- When were you/they diagnosed?: February 16, 2015
- Age at diagnosis: 66
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