Blood and urine tests to track kidney function, protein levels, and complement activity over time. For more information on how to monitor your kidney health, click here.
Your Diagnosis and Care Journey - Step by Step
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Receiving a diagnosis of Complement 3 Glomerulopathy (C3G) or primary Immune Complex-Mediated Membranoproliferative Glomerulonephritis (IC-MPGN) can be a lot to navigate. It may take time to fully understand what these conditions mean and how to live with them.
While everyone’s experience is different, many people go through similar stages, from noticing early symptoms to working closely with their healthcare team to develop a personalised care plan. Knowing what to expect along the way can help you feel more prepared and less alone.1
2026-02-12
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Identifying Early Signs and Symptoms
For some people, the first signs are subtle. You might notice:
- Feeling more tired or having lower energy than usual
- Swelling around the ankles, legs, hands, or eyes, which can be a sign that the body is retaining fluid
- Changes in urine, such as it looking darker or foamier than usual, or changes in how often you need to go to the toilet
- A reduced appetite or a general feeling of being unwell can also be an early sign that your kidneys may not be working as they should2
Katharina, who lives with C3G, describes what she noticed early on: ‘I was having this fatigue, which wasn’t usual for me. I was very tired and had frequent headaches and then just started to see that day by day my calves were getting swollen. As it was getting worse my parents decided to get it checked, all the [further] checks led to a diagnosis’
It's important to remember these symptoms can have many possible causes, the next step is usually testing so you and your healthcare team can understand what is going on and to guide the next steps in your care.
Initial Testing and Referral
When symptoms or changes in urine are noticed – sometimes even during a routine check-up – a doctor or nurse may suggest some initial tests to check how the kidneys are working. These may include:
- Urine tests: A simple dipstick or laboratory test can look for protein or blood in the urine3
- Blood tests: These measure substances such as creatinine and calculate the estimated glomerular filtration rate (eGFR), which shows how well your kidneys are filtering your blood3
If results show anything unusual, your doctor will usually refer you to a kidney specialist (nephrologist) for further assessment and support.
Getting a Clearer Picture
When you see a nephrologist, they may suggest further tests to help clarify what is happening in the kidneys. This might include:
Understanding your Diagnosis
When the results are ready, your nephrologist will talk you through what they mean for you, and whether they are consistent with C3G or primary IC-MPGN,
Both of these are rare forms of glomerulonephritis, a condition that involves inflammation or damage to the glomeruli – the tiny filtering units inside the kidney:2
- C3G: This occurs when part of the immune system (the complement pathway) becomes overactive, leading to a build-up of a protein called C3 in the kidney’s filters
- Primary IC-MPGN: This involves the build-up of immune complexes (clusters of immune proteins) in the glomeruli, which can contribute to inflammation and affect how the kidneys work
Hearing these names for the first time can feel confusing, so it’s okay to ask your healthcare team to explain it again in simpler language and help you understand what this means for your care.
These tests can feel worrying, but they are a routine and important part of confirming a diagnosis of a glomerular condition. Your healthcare team carries out these assessments regularly and will be able to explain what will happen and how you can prepare.
Ongoing Follow-Up
For many people, once your care plan has been agreed the next stage is ongoing follow-ups. You will have regular appointments with your nephrologist to check how your kidneys are doing and whether any part of your plan needs to be adjusted. These visits typically include blood and urine tests, checks of your blood pressure and weight, and sometimes discussion around lifestyle or wellbeing.3
Each appointment is an opportunity to ask questions, share how you have been feeling, and raise any new concerns.
Between visits, some people find it helpful to keep a simple symptom diary. You might note any changes in your energy levels, appetite, swelling, or urine. Over time, this record can help you and your healthcare team spot patterns and better understand how your condition is affecting you.
It’s important to remember that you don’t have to navigate this journey alone. Support is available, and over time, many people find ways to adapt, build resilience, and continue to live full and meaningful lives.
Support with nutrition, salt intake, hydration, and other approaches that may help with maintaining your health. For more information how diet and nutrition, click here.
Access to renal nurses, dietitians, counsellors, or social workers who can offer guidance for both physical and emotional wellbeing.
This stage usually focuses on shared decision-making. You and your healthcare team will work together to identify realistic goals, discuss your preferences, and make decisions based on clear, reliable information. You may have an open and thoughtful conversation about what matters most to you, so that your care plan reflects not only medical guidance, but also your personal wishes and priorities.
1 NephCure Kidney International (2024). C3 Glomerulopathy. https://nephcure.org/c3-glomerulopathy/
2 National Kidney Foundation. Complement 3 Glomerulopathy (C3G) (2024). https://www.kidney.org/kidney-topics/complement-3-glomerulopathy-c3g
3 KDIGO (2021). Clinical Practice Guideline for the Evaluation and Management of Glomerular Diseases (2021). https://kdigo.org/wp-content/uploads/2017/02/KDIGO-2021-Glomerular-Diseases-Guideline_English_LN-2024-Update.pdf