FAQs
Have questions? You’re not alone.
Living with a rare kidney disease like C3G or primary IC-MPGN can feel overwhelming, but understanding what to expect can help you feel more confident and informed. See frequently asked questions and answers about living with C3G or primary IC-MPGN.
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Diagnosis
What tests are typically run to help diagnose C3G or primary IC-MPGN and monitor my kidney health?
Common tests that measure kidney function and potential damage:
uPCR (urine protein-to-creatinine ratio) – Measures how much protein and creatinine are in your urine. High protein levels (proteinuria) can signal kidney damage.
eGFR (estimated glomerular filtration rate) – Assesses how well your kidneys are filtering waste from the blood. Lower values can indicate reduced kidney function.
Genetic testing – Helps identify inherited mutations that may predispose you to complement system overactivation.
Immunological testing – Measures the activity of the complement system.
Diagnostic test:
Kidney biopsy with C3 staining – Looks for C3 fragment buildup (a hallmark of C3G) and/or immunoglobulin deposits (a hallmark of primary IC-MPGN).
How is a C3G or primary IC-MPGN diagnosis confirmed?
A kidney biopsy is needed for definitive diagnosis. The sample is stained and analyzed under a microscope to confirm the presence of C3 fragments and immunoglobulins, and help determine the type of kidney disease.
What are normal lab value ranges for uPCR and eGFR?
The normal ranges for lab values are:
- uPCR less than 150 mg/g
- uPCR (urine protein-to-creatinine ratio) is a test used to measure how much protein is in your urine. Higher levels may indicate proteinuria, which could mean your kidneys are not filtering properly
- eGFR between 90 and 120 mL/min/1.73 m2
- eGFR (estimated glomerular filtration rate) is a test used to determine how well your kidneys are filtering creatinine, a waste product in the blood. If your kidneys filter less creatinine, it can signal declining kidney function
Please keep in mind these are generalized lab values. Lab value ranges, including healthy ranges, can vary based on the lab processing the test. Healthy ranges may also differ from person to person. Always ask your doctor to interpret your specific results.
How often will I need to have blood and urine tests?
Your care team may recommend urine and blood tests (uPCR and eGFR) every few weeks to every few months, depending on your condition and treatment plan.
What happens after a C3G or primary IC-MPGN diagnosis?
You and your nephrologist will work together to build a care plan that fits your needs. With C3G or primary IC-MPGN, kidney damage can worsen over time and may lead to kidney failure, defined as an eGFR below 15 mL/min/1.73 m2. According to the National Kidney Foundation, dialysis may be needed if your kidney function falls below this level. At that point, treatment options may include dialysis or a kidney transplant. Your doctor may also discuss long-term options, like prescription medication or a transplant, although it’s important to know that a transplant isn’t a cure. Up to 60% of C3G or primary IC-MPGN patients who receive a kidney transplant may eventually lose their transplanted kidney.
Transplant
Will C3G or primary IC-MPGN return in my transplanted kidney?
There is a possibility that C3G or primary IC-MPGN can return after a kidney transplant. That’s because these diseases are not caused by problems in the kidney itself, but by an underlying issue in the immune system: complement system overactivation.
In many cases, this is driven by autoantibodies that cause the complement system to stay overactivated. Since a kidney transplant cannot treat the underlying cause of C3G and primary IC-MPGN, these diseases can continue to damage the new kidney in the same way they affected your original kidney.
Learn how these diseases can impact those with kidney transplants >
Can a kidney transplant cure C3G or primary IC-MPGN?
A kidney transplant can restore kidney function, but it is not known to be a cure for C3G or primary IC-MPGN. That’s because these diseases are driven by the complement system overactivation. A kidney transplant cannot address this underlying cause.
As a result, these diseases often return in the transplanted kidney. Up to 60% of C3G or primary IC-MPGN patients who receive a kidney transplant may eventually lose their transplanted kidney.
Management approaches
What current management approaches are available for C3G or primary IC-MPGN?
Most current treatments focus on managing symptoms and trying to preserve kidney function rather than addressing the cause. Here are some options your doctor may discuss:
ACE inhibitors and ARBs help lower blood pressure and reduce the amount of protein in your urine; both can help protect your kidneys over time.
Immunosuppressive medications can reduce inflammation caused by an overactivated complement system. They are sometimes used after a kidney transplant to help prevent transplant rejection.
Plasma therapy or plasma exchange removes harmful proteins or antibodies from the blood and are used with immunosuppressive therapy. Data to support this treatment approach are lacking.
Complement inhibitors vary and target different proteins or pathways in the complement system, which is part of the immune system.
Lifestyle
Why is mental well-being important in C3G and primary IC-MPGN?
Managing a rare disease can feel overwhelming. Anxiety, depression, and fatigue are common. Mental health care is an important part of your overall treatment plan.
Please talk to your doctor or a mental health professional if you have concerns about your mental well-being.
Will I need to change my diet after being diagnosed with C3G or primary IC-MPGN?
If C3G or primary IC-MPGN is a part of your life, proper nutrition is an important part of supporting your kidneys. These resources can help you support your kidneys without sacrificing flavor!
The American Association of Kidney Patients publishes a nutrition counter with sodium, potassium, and phosphate levels in hundreds of foods.
The American Kidney Fund® Kidney Kitchen® features recipes for all stages of kidney disease.
The National Kidney Foundation offers the NKF Nutrition Coach website with information on kidney-friendly eating.
Community and support
What support groups are available to connect with others who have C3G or primary IC-MPGN?
Talking with others who understand your experience can reduce feelings of isolation and offer practical advice. Many groups meet online or in person.
How can I advocate for myself or a loved one?
- Ask questions at appointments
- Keep a health journal or symptom tracker
- Bring someone with you to visits
What resources are available to help me speak to my doctor about my C3G or primary IC-MPGN?
Talking to your doctor about a rare disease like C3G or primary IC-MPGN can feel overwhelming but there are resources that can help.
You can access tools designed to help guide your next appointment, including a doctor discussion guide that can help you organize your symptoms, questions, and treatment goals.
Download the doctor discussion guide
Explore more tools and support options >
These resources can help you feel more prepared and empowered to take the next step in your treatment journey.
