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After a recent diagnosis of complement 3 glomerulopathy (C3G), it’s natural to feel anxious as you wait for your treatment plan. Doctors usually recommend a combination of lifestyle changes and medications to treat these kidney diseases (also called renal diseases). These treatment options are designed to protect kidney function, support overall kidney health, and regulate the immune system to reduce further damage.
This article covers seven types of treatments doctors use for C3G and how these therapies work. It also discusses clinical trials as an option for treating kidney disease. To learn more about your treatment plan or whether you qualify for a clinical trial, talk to your nephrologist (kidney specialist).
C3G is a set of rare diseases that damage the small filters in the kidneys, known as glomeruli. These tiny blood vessels filter toxins and waste from your blood to make urine. The two types of C3G are C3 glomerulonephritis (C3GN) and dense deposit disease (DDD). If you were diagnosed with C3G before 2013, you may know C3GN and DDD as mesangioproliferative or membranoproliferative glomerulonephritis (MPGN).
C3G gets its name from a complement protein called C3. It is a rare kidney disease that develops when the complement system — part of the immune system that helps fight bacteria and viruses — becomes overactive. Too much C3 then triggers other complement proteins and damages the kidneys.
These proteins form C3-containing deposits (with little or no antibody) that build up in the glomeruli and damage the filters. Over time, this damage can result in chronic kidney disease or even kidney failure if it’s not treated.
Some people with C3G have monoclonal gammopathy. In this condition, the immune system makes abnormal antibodies, or immune system proteins. If you have C3G and monoclonal gammopathy, your doctor may change your treatment plan.
C3G treatments focus on calming the immune system to prevent it from attacking the kidneys. Below are seven ways doctors treat these diseases to improve symptoms and life expectancy with C3G.
C3G is a chronic (long-lasting) disease, which means it usually continues over time rather than going away on its own. However, it’s not the same as chronic kidney disease (CKD). CKD is a broad term for many different long-term kidney problems, while C3G is one specific rare disease that can cause CKD as it damages the kidneys. In other words, all C3G is chronic, but not all chronic kidney disease is C3G.
No matter what type of C3G you have, your doctor will likely recommend making healthy lifestyle changes. The overall goal is to support your kidney health and prevent further damage. Treatment usually includes healthy lifestyle changes and medicines like ACE inhibitors or ARBs. Many people also need additional treatments to control the disease.
Hypertension (high blood pressure) negatively affects many aspects of health. In the kidneys, the extra pressure on blood vessels causes them to narrow. This narrowing limits blood flow to the kidneys and prevents oxygen and nutrients from reaching the organ tissues. Without enough blood flow, your kidneys can no longer work properly.
Doctors treat high blood pressure by:
ACE inhibitors and ARBs also help treat proteinuria, which is extra protein in the urine. Proteinuria is a sign of kidney damage seen in people with C3G.
If you have high cholesterol levels, your doctor may prescribe medication to bring them down. Extra fat or lipids, like cholesterol in your blood, can damage the kidneys. Statins are drugs that help lower your cholesterol levels and also protect against heart disease.
Some people with C3G make autoantibodies. These are immune system proteins that attack the body’s own tissues by mistake and switch on the complement system when it isn’t needed. This ongoing activation harms the kidneys.
Corticosteroids are also called steroids. These lab-made medications help control inflammation from an overactive immune system. They work similarly to the hormone cortisol that’s naturally found in our bodies. Prednisone is a commonly prescribed oral (taken by mouth) corticosteroid that treats inflammatory diseases.
Doctors prescribe prednisone along with immunosuppressant medications to treat moderate to severe C3G. Your doctor may have you take prednisone daily or every other day to see if your kidney function gets better.
Prednisone can cause many side effects, including weight gain, high blood sugar levels, and blurry vision. To avoid these side effects, your doctor will start to lower or taper your dose over time.
Immunosuppressants work by calming the immune system. Doctors sometimes use immunosuppressants to treat C3G because they can stop autoantibodies from attacking the kidneys. Examples of immunosuppressive medications for C3GN and DDD include:
Doctors typically prescribe mycophenolate mofetil with prednisone for C3G. Common side effects of MMF include nausea, vomiting, loss of appetite, and sleep problems.
Another treatment option for C3G is monoclonal antibodies. Doctors typically prescribe these medications to people when mycophenolate mofetil and prednisone don’t work. Monoclonal antibodies are protein drugs (immunoglobulins) that block a specific part of the immune system.
Eculizumab (Soliris) and ravulizumab (Ultomiris) are medicines that block part of the immune system called complement protein C5. They are given by intravenous infusions (into a vein). These drugs are not officially approved by the FDA for C3G, but doctors sometimes use them off-label or in clinical studies when other treatments don’t work.
Rituximab is another antibody medicine that lowers certain immune cells called B cells. Some doctors may try rituximab for C3G, but it is also not FDA-approved for this disease, and research results have been mixed.
If you have moderate to severe C3G and taking mycophenolate mofetil plus prednisone hasn’t worked for you, your doctor may order a plasma infusion. Plasma is the liquid part of blood that contains proteins. A plasma infusion is given to people with factor H defects to replace the missing protein. Factor H defects are genetic conditions in which the body doesn’t have a protein that’s needed to control the immune system properly, which can lead to kidney problems and a higher risk of infections.
Doctors may also use plasma exchange to filter autoantibodies from the blood. A machine then pumps the filtered blood back into the person’s vein. The National Kidney Foundation notes that plasma infusion and plasma exchange are difficult treatments and may not work for everyone.
Doctors and researchers are always looking for new and better ways to treat glomerular diseases like C3G. In recent years, drugs called complement inhibitors, which block specific parts of the complement system, have been increasingly studied as a possible way to treat a variety of diseases, including those that affect the kidneys.
In March 2025, the U.S. Food and Drug Administration (FDA) approved the medicine iptacopan (Fabhalta) for adults with C3G to help lower protein in the urine. This was the first FDA-approved drug for C3G. It is also approved for the rare kidney disease immunoglobulin A nephropathy (IgAN) and for a rare blood disorder called paroxysmal nocturnal hemoglobinuria.
A few months later, in July 2025, the FDA also approved pegcetacoplan (Empaveli) for people 12 years and older with C3G or a related kidney disease called primary IC-MPGN. Pegcetacoplan also works by blocking part of the complement system and helps lower protein in the urine.
Results of a 2024 phase 3 clinical trial (late-stage research) found that participants receiving both oral iptacopan and supportive care experienced lasting benefits over 12 months. These included a significant reduction in proteinuria, seen as early as 14 days after starting treatment, and an improved glomerular filtration rate (eGFR), a measure of how well the kidneys filter waste from the blood.
Iptacopan blocks complement factor B to stop the complement system from attacking the kidneys. Other complement inhibitors being studied in clinical trials work differently, but also affect the complement system.
Some people with C3G have so much kidney damage that they develop end-stage kidney disease (kidney failure). This means their kidneys no longer work well enough to keep them healthy. In most cases, the damaged kidneys are not removed.
Kidney transplants may not work for everyone with C3G. Recurrence (return of disease) happens in 55 percent to 86 percent of people with C3G after kidney transplantation, typically soon after the transplant. Recurrence can harm the transplanted kidney and is the second most common cause of graft loss, following rejection.
C3G can also damage the newly transplanted kidney because the body continues to make complement proteins that attack healthy kidney tissue. It’s important to stick with your C3G treatment plan to prevent further damage.
On MyKidneyDiseaseTeam, people share their experiences with kidney disease, get advice, and find support from others who understand.
What treatments has your doctor prescribed for C3 glomerulopathy? Let others know in the comments below.
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My story pretty much fits into the the article above. Many years prior to my C3GN diagnosis. I'm 68, don't smoke and drink have been a vegatarian for almost 10 years. I had some heart stents inserted… read more
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