When your C3 glomerulonephritis, a rare kidney disease caused by uncontrolled activation of the complement system that damages the filtering units of the kidneys. Also known as C3 GN, it doesn't come from infections or diabetes—it happens when your body's own immune system attacks your kidneys without warning. Unlike more common kidney problems, C3 glomerulonephritis isn't triggered by high blood sugar or long-term high blood pressure. Instead, it's rooted in the complement system, a group of proteins in the blood that normally fight off germs but can turn against the body in this disease. This system goes haywire, leaving behind deposits of a protein called C3 in the kidney filters, which slowly clogs them up and leads to blood and protein leaking into urine.
People with C3 glomerulonephritis often don’t feel sick at first. The first sign? Blood in the urine—sometimes visible, sometimes only found in a lab test. Swelling in the legs, high blood pressure, and declining kidney function follow over time. Diagnosis isn’t simple. You need a renal biopsy, a small tissue sample taken from the kidney to look for the telltale C3 deposits under a microscope. Blood tests show low levels of C3 protein, but normal levels of other complement proteins like C4, which helps doctors rule out other diseases. There’s no single blood test that confirms it—you need the biopsy, plus a pattern of symptoms and lab results to put the pieces together.
Treatment is tricky because there’s no cure. Doctors try to slow down the damage using immunosuppressants, drugs that calm the overactive immune system, like corticosteroids, cyclophosphamide, or rituximab. Some patients get blood pressure meds like ACE inhibitors to protect the kidneys and reduce protein loss. Newer drugs targeting the complement system directly—like eculizumab or avacopan—are being tested, but they’re expensive and not yet standard. What works for one person might not work for another. That’s why tracking your kidney function over time, watching your urine, and staying in close contact with your nephrologist matters more than any single drug.
The posts below cover real cases, treatment challenges, and how other kidney conditions compare. You’ll find insights on managing side effects from immunosuppressants, understanding lab results, and what to ask your doctor when treatment isn’t working. No fluff. Just what you need to know to navigate this condition with more confidence.
Glomerulonephritis is an immune attack on the kidney's filtering units, causing protein or blood in urine, high blood pressure, and fatigue. Learn the types, treatments, and why early diagnosis matters.