Also called C3G, this rare kidney disease often affects children and young adults, but it can happen at any age. It has major impact on a person’s health and life.
C3G has two forms: dense deposit disease (DDD) and C3 glomerulonephritis (C3GN). Either form can be caused by genetic issues that may or may not be inherited, or by health complications that happen during life. In both, there are problems with the complement system that helps fight infections in your body.
What Causes It?
Small filters in your kidneys called glomeruli clean your blood and help keep you healthy. In DDD and C3GN, damaged glomeruli allow proteins, along with red and white blood cells, to get into your urine. This messes with your kidney function. Over time, this damage can lead to kidney failure.
Some studies show DDD may affect younger people more than C3GN does.
Symptoms
Each person with C3G may have different symptoms, so it’s important to know all possible signs. They include:
Proteinuria. This is when there’s too much protein in your urine. It might be cloudy, foamy, or dark. In severe cases of proteinuria (nephrotic syndrome), you might have symptoms in other parts of your body such as edema (see below).
Hematuria. This happens when your glomeruli are damaged and spill red blood cells into your urine. It might look red, pink, or brown.
Gout. Uric acid is a waste product in your blood. When it builds up in your joints, it can be painful. This can happen when your kidneys don’t take out enough uric acid from your blood. The acid can then build up, and that might affect your joints.
Edema. This swelling tends to happen in your feet, hands, and ankles, or around your eyes. It can happen when your kidneys don’t work well and you get a buildup of fluid.
Oliguria. This can happen when you don’t pee enough. With advanced C3G, your kidneys can’t create a normal amount of pee.
High blood pressure. If your kidneys don’t work right, fluid can build up and lead to high pressure in your arteries.
Fatigue. Since your body can’t filter out waste well when you have C3G, waste can build up in your blood. This can affect your brain and make you sleepy. You might also have a hard time with focus or alertness. Kidney disease can also lead to anemia (low blood count), which can also make you tired.
Infections. Your complement system fights bacteria and viruses. But since it doesn’t work right with C3G, your body might not be able to overcome infections as well. This can cause you to get sick more often.
Kidney failure. BothDDD and C3GN can keep your kidneys from working. If your kidneys fail, waste products left in your blood can make you unhealthy. If your condition becomes severe, you might need dialysis or a kidney transplant.
Along with these signs of C3G, other symptoms of kidney failure include nausea, vomiting, lack of appetite, trouble sleeping, dry and itchy skin, a metallic taste in your mouth, and muscle cramps (especially at night).
Acquired partial lipodystrophy. This happens when fat is stored irregularly under your skin. With C3G, you might have some areas on your body that are thin from lack of fatty tissue. That’s because your complement system can destroy your fat cells. But other parts of your body might look larger. That’s because they’ve stored more fat.
Eye problems. These can come from a buildup of deposits of proteins and fats (also called drusen) in light-sensitive parts at the back of your eye (the retina). These can cause you to have vision problems, especially later in life.
Getting a Diagnosis
Your doctor will use a kidney biopsy to see if you have C3G. It’s the only way to get a correct diagnosis. In this procedure, they’ll remove a small piece of your kidney to examine in a lab. You may also have genetic testing, or blood and urine tests.
Questions for Your Doctor
You may want to ask your doctor some questions to learn more about your condition. Those might include:
- How did I develop C3G?
- Which type of C3G do I have?
- What are the best ways I can control my health with this condition?
- What are my treatment options?
- What can I expect in the future with this disease?
Path to Treatment
There’s no single best treatment for C3G, and research into new therapies is ongoing. But there are some that might help you feel better.
For example, treatments that focus on your blood pressure control and proteinuria may slow down the progression of C3G. That’s because they may help reduce the amount of protein spilling into your urine. They include:
- Angiotensin-converting enzyme (ACE) inhibitors
- Angiotensin II type-1 receptor blockers (ARBs)
And if you have hyperlipidemia (when your cholesterol is too high), drugs used to lower your cholesterol may also help reduce problems in other parts of your body. Research shows they may slow down the rate of your C3G getting worse.
Another option may be a combo of glucocorticoids and mycophenolate mofetil (MMF). These are drugs that suppress your immune system. Studies show they may help prevent relapses of C3G in some people.
Also, an anti-complement drug called eculizumab (Soliris) might help lower your proteinuria and slow down your progression of C3G.
New therapies being studied for treatment of C3G include the drug iptacopan (LNP023). The FDA gave this drug a Breakthrough Therapy Designation and a Rare Pediatric Disease Designation. That means research into its effectiveness for C3G will be fast-tracked.
Taking Care of Yourself
In addition to your medical treatment, it’s important that you look after yourself if you have C3G. To do so, make sure you:
Eat a healthy diet. Fill your meals with fruits, vegetables, starchy and whole-grain foods, and foods with low saturated fats, salts, and sugars. Keep some dairy and other sources of protein (like fish, beans, or meat) in your diet as well.
Your doctor may have you limit your potassium, sodium, or phosphate.
A well-balanced diet can help you avoid other issues alongside your C3G.
Stay on top of your health. Even if you feel great, it’s important that you stick to your routine and take all your meds. Always tell your doctor if you have any concerns or strange symptoms. If you take other drugs or supplements, tell your doctor to make sure they don’t interact with your C3G treatment.
Exercise. Proper physical activity will help you sleep, boost your energy, keep your bones strong, and help you ward off depression. Exercise also lowers your risk of heart disease and other complications.
If you’re on dialysis, you may not be able to exercise as much. Ask your doctor about the best exercise plan for you.
Stop smoking. This will improve your overall health. Ask your doctor if you need help quitting.
Limit alcohol. Ask your doctor if it’s OK to drink in moderation. Let them know If you need help cutting back or stopping.
What to Expect
After your C3G diagnosis, your care team will help you find the best treatment plan. You might be able to join a clinical trial. But those might be hard to find since this is a rare disease.
In severe cases, you might eventually have dialysis or a kidney transplant. But there’s a high chance of C3G coming back after a transplant. Talk to your doctor about the best options for you.
How C3G Can Change Over Time
Your symptoms may get worse. About half of people with C3G eventually get end-stage renal disease, or ESRD. This often happens within 10 years of your diagnosis.
ESRD, which is life-threatening, means your kidneys can’t filter fluids and waste from your body well enough.
Where to Find Support
To find support, look into the National Organization for Rare Disorders (NORD) (rarediseases.org) or Disease Info Search (diseaseinfosearch.org). There’s also an online support community for those living with C3G. It’s provided through the National Kidney Foundation.
To learn more about your possible risk for C3G, ask your doctor about genetic testing.
Meet the Care Team
With C3G, your team will likely include your primary doctor plus a nephrologist (a doctor who specializes in kidney problems), a hematologist (a doctor who works with blood diseases), a transfusion medicine team (who’ll test your blood), a pathologist (a doctor who examines tissue samples), and a laboratory medicine team.