Hi forum friends,
I am wondering about how to get a sense of the level of healthy IGG once M-spike is taken into account. I have seen posts that say
Healthy IGG = (Measured IGG) - (M-spike)
When I mentioned this to the research fellow at my myeloma center, I was met with a chuckle and an “It’s much more complicated than that.” Can anyone provide the information on how this calculation is done, or where I can find information about it? If it is too complicated to spell out here, are there any resources that state the equation I wrote out above is a reliable rough estimate of healthy IGG levels?
Thank you.
ML
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Re: Calculating healthy levels of involved immunoglobulin
Hi MyeLens,
Hmmm. My local hematologist indicated to me that this is how he judges the the level of the healthy (polyclonal) level of an involved immunoglobulin in a myeloma patient. But while my local hematologist is great, he is also not a myeloma specialist.
Assuming your myeloma is of the IgG isotype variety (i.e. you have only an IgG M-spike as confirmed by immunofixation, and not an IgA or IgM m-spike), I don't know how else one would measure it. I also have never seen an article that discusses how one might measure it.
Note that the above method may not be as accurate for patients with an IgA istotype since IgA M-spike values measured via an SPEP can sometimes be untrustworthy.
I have had two lab tests where my total IgG level was less than my IgG M-spike. I have always written these kinds of findings off to lab error since I thought these kinds of results were impossible (i.e., how could one have a negative value for the healthy IgG level?). But maybe there is actually more to measuring the healthy IgG level in myeloma patients than the simple formula you mentioned?
Hmmm. My local hematologist indicated to me that this is how he judges the the level of the healthy (polyclonal) level of an involved immunoglobulin in a myeloma patient. But while my local hematologist is great, he is also not a myeloma specialist.
Assuming your myeloma is of the IgG isotype variety (i.e. you have only an IgG M-spike as confirmed by immunofixation, and not an IgA or IgM m-spike), I don't know how else one would measure it. I also have never seen an article that discusses how one might measure it.
Note that the above method may not be as accurate for patients with an IgA istotype since IgA M-spike values measured via an SPEP can sometimes be untrustworthy.
I have had two lab tests where my total IgG level was less than my IgG M-spike. I have always written these kinds of findings off to lab error since I thought these kinds of results were impossible (i.e., how could one have a negative value for the healthy IgG level?). But maybe there is actually more to measuring the healthy IgG level in myeloma patients than the simple formula you mentioned?
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Multibilly - Name: Multibilly
- Who do you know with myeloma?: Me
- When were you/they diagnosed?: Smoldering, Nov, 2012
Re: Calculating healthy levels of involved immunoglobulin
Thank you, Multibillly. I plan to ask about this again at my next appointment, and I will post if I get a response that I can adequately convey. From what I have read, suppression of the involved immunoglobulin seems to be another important factor, so I want to make sure I fully understand.
Re: Calculating healthy levels of involved immunoglobulin
Hi MyeLens and Multibilly,
Dr. Jason Valent discussed this subject in this post here in the forum. He states the healthy IgG can be calculated as follows: Total IgG Level less M-spike equals Healthy IgG.
For example, IgG level of 2500 (2.5 g/dL) and M-spike of 1.5 g/dL (1500 mg/dL) equals Healthy IgG of 1000 mg/dL.
Dr. Jason Valent discussed this subject in this post here in the forum. He states the healthy IgG can be calculated as follows: Total IgG Level less M-spike equals Healthy IgG.
For example, IgG level of 2500 (2.5 g/dL) and M-spike of 1.5 g/dL (1500 mg/dL) equals Healthy IgG of 1000 mg/dL.
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smarty - Name: Marti
- Who do you know with myeloma?: myself Smoldering Myeloma
- When were you/they diagnosed?: May 1, 2015
- Age at diagnosis: 76
Re: Calculating healthy levels of involved immunoglobulin
Thank you Smarty. I appreciate the link to the post by Dr. Valent.
So, using the equation we both posted, an IgG of 2500 mg/dL minus an M-spike of 2.4 (2400 mg/dL) equals a healthy IgG of 100 mg/dL.
So, using the equation we both posted, an IgG of 2500 mg/dL minus an M-spike of 2.4 (2400 mg/dL) equals a healthy IgG of 100 mg/dL.
Re: Calculating healthy levels of involved immunoglobulin
MyeLens,
If your healthy IgG is quite low and you start to catch bugs frequently and/or develop persistent infections, your doctor may consider administering IgG therapy. There are quite a few folks on this forum that receive IgG injections to help boost their IgG levels.
But I would also go back and look at your earlier lab results and see if your healty IgG level was as suppressed as it is now. I have found that lab results can be wrong more times than you might think would be normal.
If your healthy IgG is quite low and you start to catch bugs frequently and/or develop persistent infections, your doctor may consider administering IgG therapy. There are quite a few folks on this forum that receive IgG injections to help boost their IgG levels.
But I would also go back and look at your earlier lab results and see if your healty IgG level was as suppressed as it is now. I have found that lab results can be wrong more times than you might think would be normal.
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Multibilly - Name: Multibilly
- Who do you know with myeloma?: Me
- When were you/they diagnosed?: Smoldering, Nov, 2012
Re: Calculating healthy levels of involved immunoglobulin
I am quite sure the formula is correct as long as it is used carefully. I also think it will be difficult to find a reference discussing the formula in a publication or anything similar because it's so basic.
To ensure the formula is used correctly, it might be best to rewrite it as:
Healthy IgX = (Total IgX) - (M-spike of type IgX)
where "X" is the immunoglobulin isotype, so either "G," "A", "M", "D", or "E", meaning IgG, IgA, IgM, IgD, or IgE, respectively.
One possible criticism of the formula is that it won't hold if a patient has an M-spike consisting of more than one type of immunoglobulin, say IgG and IgA. That is not unheard of. So you have to subtract off from the (Total IgX) only the part of the M-spike that is the same kind of immunoglobulin.
The other issue is that different methods are used for estimating the total immunoglobulin level and M-spike level, and the methods are not coordinated to ensure that the measured M-spike is always less than the total immunoglobulin level. So the formula can estimate negative "healthy" (polyclonal) immunoglobulin levels, particularly in patients with suppressed involved immunoglobulin levels. That doesn't mean the formula is wrong; it just means the estimate it generates is not as precise as one might like.
To ensure the formula is used correctly, it might be best to rewrite it as:
Healthy IgX = (Total IgX) - (M-spike of type IgX)
where "X" is the immunoglobulin isotype, so either "G," "A", "M", "D", or "E", meaning IgG, IgA, IgM, IgD, or IgE, respectively.
One possible criticism of the formula is that it won't hold if a patient has an M-spike consisting of more than one type of immunoglobulin, say IgG and IgA. That is not unheard of. So you have to subtract off from the (Total IgX) only the part of the M-spike that is the same kind of immunoglobulin.
The other issue is that different methods are used for estimating the total immunoglobulin level and M-spike level, and the methods are not coordinated to ensure that the measured M-spike is always less than the total immunoglobulin level. So the formula can estimate negative "healthy" (polyclonal) immunoglobulin levels, particularly in patients with suppressed involved immunoglobulin levels. That doesn't mean the formula is wrong; it just means the estimate it generates is not as precise as one might like.
Re: Calculating healthy levels of involved immunoglobulin
Thank you, Multibilly and Cheryl, for your helpful responses.
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