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Updated on December 26, 2025
Complement 3 glomerulopathy (C3G) and immune complex membranoproliferative glomerulonephritis (IC-MPGN) are complement-mediated renal diseases, kidney diseases caused by abnormal functioning of the complement system.
The complement system is made up of dozens of different proteins that circulate in the body. These proteins activate when they encounter something that needs attention from the immune system, such as a disease-causing germ or an infected cell. Activated complement proteins trigger the activation of other parts of the immune system, like white blood cells, inflammatory proteins, and other substances that help get rid of infections and damaged cells.
While distinct and different conditions, both C3G and IC-MPGN cause protein deposits to accumulate in the kidneys. These deposits clog the glomeruli, the delicate filtering structures within the kidneys. This leads to inflammation, damage, and a loss of kidney function. Both C3G and IC-MPGN lead to kidney failure in a significant number of cases.
Treatment for C3G and IC-MPGN
There is no cure for either C3G or IC-MPGN, but there are treatments. Treatment focuses on disease management, including slowing the progression of kidney damage and preventing complications. While distinct conditions, C3G and IC-MPGN overlap in how they are managed. A treatment plan can include:
- Medications to help control blood pressure, cholesterol, and protein in the urine (proteinuria)
- Medications that act on the immune system, including corticosteroids and newer medications called complement inhibitors.
- Treatment of underlying health conditions (infections and autoimmune diseases are associated with IC-MPGN)
- Changes to nutrition and lifestyle to help prevent damage to the kidneys, such as reducing sodium and protein intake and staying active
Treatment will vary from person to person and depend on which condition a person has and other factors, like symptoms and kidney function. Your best source of information will always be a healthcare provider.
Monitoring is an essential part of treatment
Regular tests to monitor for kidney function and other markers of health are an essential part of treatment for all types of kidney disease. Monitoring can help you and your healthcare provider understand how these conditions are responding to treatment.
If you are living with C3G, IC-MPGN, or a similar kidney disease, it’s important to understand why certain tests are ordered and what the results mean.
Some tests used to guide treatment for C3G and IC-MPGN include:
Urine tests
This is a urine test that measures the amount of protein, albumin (a type of protein), and blood in the urine. Normally these substances are not found in the urine or are found in minuscule amounts. Higher amounts are a sign of declining kidney function.
Glomerular filtration rate (GFR)
This is a measurement of how much blood the kidneys are filtering per hour. Most often this is measured with what is called an “estimated GFR,” which is calculated by measuring the amount of creatinine in the blood and/or urine. Creatinine is a waste product created when the body digests proteins and is normally excreted in the urine.
Blood pressure
This is a measurement of the force that blood exerts on the walls of blood vessels as it moves through the body. This is measured with a blood pressure cuff. High blood pressure is a potential complication of kidney disease, and it can cause damage to the heart, blood vessels, and brain if not controlled.
Cholesterol
Also called a lipid panel, this is a blood test that measures cholesterols and other fats circulating in the blood. Elevated levels are a potential complication of kidney disease, can contribute to kidney disease, and also contribute to cardiovascular disease and other health problems.
Blood glucose
Blood glucose levels are another number to monitor and discuss with a healthcare provider. Also known as blood sugar, glucose is the body’s main source of energy. Levels that are too high (hyperglycemia) are a symptom of diabetes and prediabetes, two of the most common health conditions in the United States. These conditions are associated with another type of kidney disease called diabetic kidney disease (DKD) and are also associated with dysregulation of the complement system.
