What testing should be done to confirm an MGUS diagnosis?
So monoclonal gammopathy determine significance is a very common condition among people above the age of 50. About 3 to 5% will have that. Basically on a blood test that is a monoclonal protein, but we don't find any other illness, or symptoms related to that monoclonal gammopathy, for example, in multiple myeloma, you have high calcium, renal failure, anemia, bone disease that is not present when you have MGUS. And, if you look at the bone marrow, there are very few plasma cells, less than 10%. In general, I think if I see a patient who was discovered to have monoclonal gammopathy, that is quite small, there is no renal failure, anemia, high calcium, or bone disease. I may just monitor them without any further investigation. I may not do a bone marrow aspirate right away and just see what happens. If I do a bone marrow aspirate, and I find that they have about 3-5% plasma cells, I mean, less than 10%, and no other symptoms, then I don't see any reason to repeat the bone marrow on a routine basis. I think monitoring the patient and clinically to see if there's any symptoms and try to address that. Obviously, you need to make sure you are ruling out rare diseases when the patient has monoclonal gammopathy such as amyloidosis. So clinical history and investigating that is very important.
Should a bone marrow biopsy or imaging be part of the MGUS determination testing?
So it depends on what parameters you're seeing for MGUS. So a lot of MGUS is what we call low-risk MGUS, meaning that the M spike is very small. It's less than 1.5, the ratios, the kappa and lambda ratio is normal and it's usually an IgG subtype. So it has been shown using data from Mayo Clinic where they've studied thousands of patients, that if you had these three features, you know, low volume disease, very small M spike, normal ratio, and it's IgG subtype, getting a bone marrow biopsy or getting imaging is not going to change the diagnosis. You're not going to find a lot of plasma cells. You will confirm that it's MGUS if you do a bone marrow and you're probably not going to find any lytic bone lesions. So for those low-risk patients with MGUS, as long as I examine them and I talk to them, and I make sure they don't have any of those other symptoms that I might attribute to MGUS, I am comfortable with not doing further testing in the sense of bone marrow and imaging, and I usually just like get another set of labs. So for the first time I see somebody, I probably will repeat labs in six months. And then after that it sort of depends. But it becomes less frequent. Now if somebody has one of those risk features of MGUS, you could often don't, but you could miss a diagnosis of something more. So it makes sense to do a bone marrow biopsy and some sort of skeletal imaging. You want to do more than a skeletal survey, because an x-ray can often miss those lesions. So you either get a CT scan of the bones, which is my preference for patients with MGUS or you can get an MRI or PET-CTs as some sort of imaging. And a bone marrow biopsy is indicated for patients who are not low-risk MGUS.
Should a person diagnosed with MGUS have imaging done?
We did a study using the myeloma quality database where we looked at patients, having a myeloma. So it's not a prospective study on MGUS patients presenting and in protein, it's patients that are diagnosed with multiple myeloma. And we looked at patients with M protein levels less than 15 gram, which if it was Polito if it was IgG and ten gram, when it was IgA, they should have a normal kappa/lambda ratio and normal blood samples, meaning no elevation of creatinine, no anemia, nothing of that. And we actually saw that among these patients, we had bone lesions. And even though the results from the bone marrow sampling was a mean value of maybe 12, I think it was 12% infiltration, so they had smoldering. But when you assess these patients with a CT of the skeleton, actually 25% of them had bone lesions. So then the questions, why is it more important to have a CT scan of your skeleton? Because then you are symptomatic myeloma? Or does it mean anything if you are ten, 12 or 14% infiltration in the bone marrow? We do both. But I think if I should choose, then I would choose a CT of the skeleton in these patients with a low protein level.
Should genetic testing be done?
So it's a very good question. We are doing now on research level, next generation sequencing to look at a very deep level. Who are the patients who may progress in their lifetime? Not all MGUS are the same. There's MGUS that would never progress to myeloma. And that's great. They can enjoy life and there's MGUS that may actually progress. And we know that every single patient with myeloma must have had an MGUS in their lifetime, or smoldering myeloma in their lifetime. So let's detect it then and figure it out before they develop myeloma in their future.
HealthTree • July 22, 2024
