C3 Glomerulonephritis: Causes, Diagnosis, and Treatment Options

When your C3 glomerulonephritis, a rare kidney disease caused by uncontrolled activation of the complement system that damages the filtering units of the kidney. It's also known as C3 glomerulopathy, and unlike common kidney problems, it doesn’t stem from diabetes or high blood pressure—it’s an immune system glitch that attacks your own kidneys. This condition shows up in blood and urine tests as protein leakage, red blood cells, and low C3 complement levels. The kidneys start to fail because the body’s defense system, meant to fight infections, turns on itself.

What makes C3 glomerulonephritis tricky is that it looks like other kidney diseases under the microscope. A renal biopsy, a procedure where a small sample of kidney tissue is removed for lab analysis is the only way to confirm it. Doctors look for specific patterns of C3 protein deposits without the usual immune complexes you’d see in lupus or post-infection kidney damage. The complement system, a group of proteins that help clear pathogens and dead cells is the real culprit here—mutations or autoantibodies cause it to stay stuck in "on" mode, slowly destroying the glomeruli.

Treatment isn’t one-size-fits-all. Some people respond to immunosuppressive therapy, medications like corticosteroids or cyclophosphamide that calm the overactive immune response. Others need drugs that directly block complement proteins, like eculizumab or newer oral inhibitors still being tested. Blood pressure control with ACE inhibitors or ARBs is standard—protecting the kidneys means keeping pressure low. But here’s the hard truth: many patients still progress to kidney failure, even with treatment. That’s why early diagnosis matters more than ever.

You won’t find C3 glomerulonephritis in every doctor’s office. It’s rare, often misdiagnosed, and requires specialists who know what to look for. If you’ve been told you have "nephrotic syndrome" or "chronic kidney disease" without a clear cause, ask about a biopsy and complement testing. The posts below cover real-world cases, drug comparisons, and how kidney specialists track this disease over time—giving you the facts you need to ask the right questions and understand your options.