What is monoclonal gammopathy of renal significance (MGRS)?

Monoclonal gammopathy of renal significance (MGRS) is a term for a group of kidney conditions caused by an abnormal protein in the blood. Certain blood cells make this protein.

MGRS isn't one kidney disease. It includes several types of kidney damage caused by these abnormal proteins. You may see MGRS on a kidney biopsy report. Or you may hear the term while your healthcare team is looking for the cause of a kidney condition.

The term monoclonal gammopathy of renal significance describes what's happening:

• Monoclonal gammopathy means that a group of identical blood cells makes an abnormal protein. It is called a monoclonal protein. It also is called an M protein.
• Renal means related to the kidneys.
• Of significance means that the protein is harming the kidneys and needs medical attention.

Depending on the specific disease, the abnormal protein may collect in different parts of the kidneys or affect the kidneys in other ways. This can make it harder for the kidneys to filter the blood and do their other important jobs.

MGRS includes several kidney diseases. They differ in how monoclonal proteins affect the kidneys and which parts of the kidneys are damaged.

MGRS may be only one of the terms you see in your medical record. These terms may include certain forms of amyloidosis, some types of glomerulonephritis and others. Your healthcare team also may give you the term for the specific kidney disease found on your biopsy.

Your care team can find the specific pattern of kidney damage and determine whether it is related to a monoclonal protein.

Kidney disease can have many causes, so having a monoclonal protein and kidney disease doesn't necessarily mean the two are related. Your healthcare team may do tests to find out whether the monoclonal protein is harming your kidneys

MGRS doesn't have one set of symptoms. That's because it includes several different kidney diseases. In some people, the first clue is found through a blood or urine test rather than something they can feel.

MGRS-related kidney disease may cause protein in the urine, blood in the urine or kidneys that aren't working as well as they should. Kidney issues may develop quickly or slowly.

Without treatment, some MGRS-related kidney diseases can get worse and lead to chronic kidney disease. Or they can lead to kidney failure in some people. Treatment can target the cells making the harmful protein and help prevent further kidney damage.

MGRS is related to both monoclonal gammopathy of undetermined significance (MGUS) and multiple myeloma, but they aren't the same.

MGUS. In MGUS, a small group of plasma cells makes an abnormal protein, but the protein doesn't cause organ damage. Many people with MGUS never develop a serious health condition from it.

But sometimes even a small group of cells can make a protein that damages the kidneys. When the protein causes kidney disease, the condition may fall under the term MGRS. The amount of this protein doesn't have to be large to cause kidney damage.

The term MGRS was developed to make this difference clear. It tells healthcare professionals that the abnormal protein isn't simply present — it's harming the kidneys.

Multiple myeloma. Having MGRS does not mean that you have multiple myeloma or another blood cancer. Both MGRS and multiple myeloma can involve monoclonal proteins and abnormal plasma cells. That's why some of the same tests and treatments may be used.

Even though MGRS isn't cancer, it can still be serious because the abnormal protein can damage the kidneys.

MGRS can be a confusing term, especially when it appears with other unfamiliar terms in a medical report. The most important thing to know is that MGRS means that an abnormal protein is harming the kidneys. MGRS isn't one specific kidney disease.

If MGRS is a possibility, your healthcare team can explain what it means, what tests you may need and what you can do to help protect your kidneys.