Thread by @VincentRK

MGRS (Monoclonal Gammopathy of Renal Significance), MGDS (Dermatologic Significance), MGCS (Clinical Significance) etc are NOT names of diseases.

They are concepts: That a monoclonal gammopathy can cause medical problems besides progression to malignancy.

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It's akin to saying someone has a bone marrow disorder as a cause for anemia.

Unless you know the specific disease, you cannot approach therapy or prognosis. Just attributing a kidney problem to a monoclonal protein is not enough for deciding therapy or counseling.

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So you need to need to both know the specific pathology AND be confident that the pathology is causally related to the monoclonal protein and not a coincidental association.

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For example if you think someone has monoclonal gammopathy causing renal damage, you have to first make the specific diagnosis: light chain deposition disease, C3 glomerulonephritis, Proliferative glomerulonephritis with monoclonal immunoglobulin deposits, Fanconi's, etc.

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Next step would be to exclude other causes and have enough evidence that a clonal process is causing the damage. Eg., glomerular deposits that are kappa and not lambda.

Just saying "MGRS" is a equal to a colloquially saying someone has a bone marrow process causing anemia.
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Monoclonal proteins are found in 5% of the general population over age 50. So in every disease if you go looking, 5% of people will have an M protein. Most are coincidental.

The onus is on us to do the right work up as needed to ensure that the association is causal.

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Over 150 diseases have been "associated" with a monoclonal protein. Most are coincidental.

There are real associations. Terms like MGRS, MGCS are to remind people to consider the real association when clinical features fit the likelihood of the M protein being the culprit.
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But they are not names of diseases. Even if proteinuria is causally related to the monoclonal protein you still need to know the pathology: is it proliferative GN, light chain deposition etc. Otherwise you cannot treat or counsel.
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For conditions like peripheral neuropathy consider that there are 100s of causes of neuropathy, of which MGUS is one. And it's usually not the problem. And even if it is, trying to eradicate it (treatment) may be worse than the clinical problem.

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With people ordering protein electrophoresis and light chains a lot we find a lot of coincidental associations. There is risk of inappropriate treatment.

So don't write MGRS as diagnosis without stating the name of the renal pathology & why u are sure it is a clonal process
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