Is this M protein a problem for your kidneys too? (Monoclonal Gammopathy of Renal Significance - MGRS) Let's talk about this!

We all know that our kidneys are a very important organ that silently does its job. However, sometimes these kidneys can also become sick silently. Today we are going to talk about a disease that causes kidney disease, which may seem a little complicated when you hear the name, but is easy to understand. This is called MGRS (Monoclonal Gammopathy of Renal Significance) . Although the name is a bit long, don't worry, let's understand it simply.

What is MGRS simply?

Okay, let's look at what MGRS is. Simply put, MGRS is a group of conditions that damage the kidneys. This damage occurs because some of our body's plasma cells , or B cells (these are types of white blood cells), make too many copies of themselves, or clones . Think of it like a photocopy machine making multiple copies of the same sheet of paper.

The plasma cells that form in this way produce a type of antibody called M protein . These M proteins deposit in various organs of our body, especially the kidneys, and begin to damage them.

The important thing is that MGRS is not cancer. However, a small number of people with MGRS can eventually develop cancer, such as multiple myeloma . So it's important to be aware of this.

Are there types of MGRS?

Yes, there are more than a dozen types of MGRS conditions. These are classified according to which part of the kidney the M protein affects. There are three main categories:

1. Glomerular diseases

The most common type of MGRS is glomerulopathies . These damage the tiny blood vessels inside the kidneys. They are like the meshes in a water filter. Some of the other diseases that fall into this category include:

• Renal amyloidosis. This includes types called AL amyloidosis, AH amyloidosis, and AHL amyloidosis.
• Cryoglobulinemic glomerulonephritis (CG).
• Fibrillary glomerulopathy (FGN).
• Immunotactoid glomerulopathy (ITG).
• Glomerular diseases associated with monoclonal proteins. This includes conditions called `light chain` and `heavy chain deposition diseases`.

2. Tubulointerstitial diseases

These diseases affect the tubes (tubules) that carry nutrients and fluids filtered by the kidneys back into the blood, and the tissues around them. Some examples include:

• Light chain Fanconi syndrome (LCFS).
• Light chain proximal tubulopathy (LCPT) without crystals.
• Crystal-storing histiocytosis.

3. Conditions affecting the blood vessels within the kidney (Intra-renal vascular lesions)

These conditions affect the blood vessels in the kidneys. An example is atypical hemolytic uremic syndrome (aHUS) . This is when tiny blood vessels in the kidneys become blocked by blood clots.

How common is MGRS?

MGRS is actually a very rare condition. It is estimated to affect less than 1% of the population. It is especially common in people over the age of 60 .

What are the symptoms of MGRS?

The symptoms of MGRS can vary depending on the type of MGRS you have. Some common symptoms include:

• Feeling very tired (fatigue) .
• Swelling in the lower legs, ankles, or feet. Sometimes the stomach, hands, or face may also swell.
• Nephrotic syndrome occurs. This is characterized by protein excretion in the urine and elevated cholesterol levels in the blood.
• Foamy or soapy urine. This may be a sign of protein in the urine (proteinuria).
• Frequent urination is the need to urinate frequently.
• Blood in the urine (hematuria) or urine that turns pink.
• Nausea and vomiting.
• POEMS syndrome . This is also a rare condition.
• Numbness, tingling, or weakness in the limbs (these are signs of neuropathy).
• Skin discoloration (light or dark spots).
• Difficulty breathing (dyspnea).

What causes MGRS?

The main cause of MGRS is kidney damage caused by the aforementioned M proteins. M proteins are a type of antibody that doesn't work properly, and is produced incorrectly. They are made from damaged clones (copies) of plasma cells, a type of white blood cell, or B cells.

Some people can have these clones of plasma cells making M proteins without harming any organs. This condition is called Monoclonal Gammopathy of Undetermined Significance (MGUS) . However, in people with MGRS, these M proteins build up in the kidneys and damage them.

What is the main cause of MGRS?

Experts still don't know exactly what causes MGRS. Autoimmune disorders , genetic changes , infections, and environmental factors are all thought to contribute to it.

What complications can occur due to MGRS?

These plasma cell clones and MGRS can cause serious complications due to kidney damage. Some of these include:

• Chronic kidney disease (CKD) .
• End-stage renal (kidney) disease .
• Kidney failure .
• Development into other diseases. In some people, the number of plasma cell clones increases so much that it can develop into a type of white blood cell cancer called multiple myeloma (MM) . MGRS can also develop into other cancers, such as Waldenström macroglobulinemia , chronic lymphocytic leukemia (CLL) , or B-cell lymphoma .

How is MGRS diagnosed?

A doctor can confirm MGRS by doing a kidney biopsy . This involves taking a small piece of tissue from your kidney and testing it for M protein. They may also test samples of your blood, urine, or bone marrow.

Is there a treatment for MGRS?

Yes, there are treatments for MGRS. Doctors treat it with drugs similar to chemotherapy for cancer. These drugs either kill the problem cells or stop them from making more copies. Other drugs can help reduce swelling. The main goal of treatment is to keep your kidneys working and stop them from getting damaged.

In some cases of MGRS, doctors may also perform a stem cell transplant . This replaces your damaged cells with healthy cells. If your kidneys are severely damaged, you may also need dialysis or a kidney transplant .

Specific medications and treatments used for MGRS

The type of medication you are given will depend on the type of MGRS you have. Here are some treatment options:

• Monoclonal antibodies - e.g. rituximab, daratumumab.
• Proteasome inhibitors - e.g. bortezomib, carfilzomib, ixazomib.
• Immunomodulatory drugs - e.g. thalidomide, lenalidomide, pomalidomide.
• Alkylating agents - e.g. cyclophosphamide, bendamustine, melphalan.
• Corticosteroids - e.g. prednisone, dexamethasone.
• Autologous stem cell transplant.

What are the side effects of the treatment?

Treatments like chemotherapy can cause many unpleasant side effects, sometimes even organ damage. That's why doctors choose treatments very carefully to get the most benefit from them and reduce the risk of serious side effects. Some of the side effects you may experience include:

• Anemia ( blood deficiency).
• Bleeding.
• Constipation.
• Diarrhea.
• Tired.
• Increased risk of viral, bacterial and fungal infections.
• The food is tasteless.
• Nausea and vomiting.

Can MGRS be prevented?

Because we don't know exactly what causes MGRS, there is currently no specific way to prevent it.

What can you expect if you have MGRS?

Although MGRS is a treatable condition, it usually does not completely go away. It can recur after treatment. If your kidneys are severely damaged, you may need a kidney transplant.

About 18% of people with MGRS will later develop a cancer called multiple myeloma. Therefore, your doctor will monitor you regularly with blood and urine samples, as this can be detected early if it occurs.

How long can you live with MGRS?

How long you can live with MGRS depends on the type of MGRS you have, its severity, and how you respond to treatment. People with less kidney damage have a better outlook than people with more severe damage. For example, in one study, people with amyloidosis associated with MGRS lived an average of about 10 years after diagnosis. But people without amyloidosis lived much longer. Also, people who respond well to treatment have the best outcomes.

How do I take care of myself?

Be sure to follow any recommendations your doctor gives you for taking care of your kidney health at home. This may include limiting things like alcohol, and controlling risk factors for kidney disease, such as high blood pressure and diabetes. While these things can't directly treat MGRS, they can help reduce the risk of further kidney damage. Your doctor can also help you manage the side effects of treatment.

When should I see a doctor?

If you have symptoms of a kidney problem, such as swelling, foamy or pink urine, frequent urination, or very little urination, be sure to see a doctor.

What questions should I ask my doctor?

It may be helpful to ask your doctor these questions:

• What treatments are available for the type of MGRS I have?
• What can I do to prevent kidney damage?
• What new or worsening symptoms should I watch for?

Finally, the most important thing (Take-Home Message)

MGRS is a serious condition that can damage the kidneys in a way that can be life-threatening. But remember, not everyone with MGRS will develop cancer. Your doctor will monitor you regularly and take steps to identify and treat any new problems as soon as possible . New treatments have now made it possible to improve your quality of life and reduce your risk of serious illnesses. So don't be afraid, follow your doctor's advice, and face this condition.

` MGRS, Monoclonal Gammopathy of Renal Significance, Kidney Disease, M Proteins, Plasma Cells, Kidney Biopsy, Nephrotic Syndrome, Multiple Myeloma