Hello Egran,
Okay, let's step through this.
First of all, your M-spike is relatively low and has been basically constant since your diagnosis. That's obviously a good thing!
Second, your kappa-lambda ratio is outside the normal range. That could have an influence on your risk of progressing to multiple myeloma, although your risk is still very low.
You probably already know this, but the standard model for categorizing MGUS patients into different risk levels for progressing to multiple myeloma is based on a study by the Mayo Clinic. It includes three risk factors:
1. Non-IgG isotype
2. Serum M protein greater than 1.5 g/dL
3. Kappa/lambda or lambda/kappa ratio being skewed, or out of normal range.
For patients with 0 of these major risk factors, the risk of progression at 20 years is 5%. For patients with 1, the risk factor is 21%. For those having 2 of these conditions, it's 37%, and for those meeting all three of those criteria, it's 58%.
(See
this forum posting for more details.)
Your MGUS "isotype" is IgG lambda, and your M-spike is less than 1.5 g/dL. So you don't have either of those two risk factors. However, your kappa-lambda ratio is out of the normal range, so you have that one risk factor, which increases somewhat your probability of progressing to multiple myeloma.
Remember, however, that we're talking probabilities here. Each individual patient is different.
Finally, there is your below-normal IgM level.
IgM is one of your "uninvolved" immunoglobulins. Your "involved" immunoglobulin is IgG. The technical term you sometimes will see for having one or more uninvolved immunoglobulins below the normal reference range is "immunoparesis."
There are some studies that suggest that immunoparesis may increase an MGUS patient's risk of progressing to multiple myeloma. See, for example, this study:
I Turesson et al, "Monoclonal gammopathy of undetermined significance and risk of lymphoid and myeloid malignancies: 728 cases followed up to 30 years in Sweden," Blood, Jan 16, 2014 (link to full text)However, my sense is that this is not a settled issue, and I think one reason it isn't is because immunoparesis often occurs in MGUS patients who also have abnormal kappa-lambda ratios. In this Italian study, for example, two thirds of the MGUS patients who had immunoparesis also had abnormal kappa-lambda ratios.
M Pezzuti et al, "Association Between Immunoparesis and a Skewed Free Light Chain (FLC) Ratio: A New Prognostic Factor Of Progression from MGUS To Multiple Myeloma?", Blood, Nov 15, 2013 (link to abstract)Also, half the MGUS patients in the study had immunoparesis.
So it's not clear to me that you need to be too concerned about the low IgM level in terms of any potential sign it may be of an increased risk of progression.
IgM is, however, important in helping your body fight infections, so you probably need to be a bit more careful about preventing infections going forward.
Also, everything I've just described is just a layman's perspective. I'm not a doctor, so you should discuss these issues with your doctor at one of your next appointments.
I hope this helps. Let us know if you have any additional questions.
