What is glomerulonephritis?
Inside your kidneys are millions of microscopic filters called glomeruli. They do the actual work of cleaning your blood — letting waste and extra fluid pass into the urine while keeping the things your body needs, like blood cells and protein, in the bloodstream. Glomerulonephritis means these filters have become inflamed or damaged, so they leak what they should keep in and clean the blood less effectively.
“Glomerular disease” is the broader term for any condition affecting these filters, whether or not active inflammation is the main driver. Some forms come on suddenly (acute); others develop slowly and quietly over years (chronic). And there are many specific types — they can look similar on the surface but are treated very differently, which is why getting the diagnosis exactly right matters more here than in almost any other kidney condition.
Because glomerular disease damages the filters, it’s also one of the causes of chronic kidney disease. The aim of treatment is to calm the injury and preserve kidney function — ideally well before any damage becomes permanent.
What are the symptoms?
The two hallmark signs are blood and protein in the urine — the filters leaking what they normally hold back. You might notice:
- Blood in the urine — pink, red, or cola-colored (or invisible, found only on a test)
- Foamy or bubbly urine, a sign of protein leaking
- Swelling in the face, around the eyes, or in the hands, feet, and abdomen
- High blood pressure, sometimes new or suddenly harder to control
- Less urine than usual, or feeling generally unwell, tired, or short of breath
Some forms announce themselves clearly — a child whose urine turns brown after a sore throat, for example. Others are silent and found only when a routine test turns up blood or protein. Because these signs overlap with many other conditions, careful evaluation is essential rather than guesswork.
Blood and protein in the urine together is the classic fingerprint of a glomerular problem. On its own it isn’t a diagnosis — but it’s a clear signal to look closer.
Nephritic vs. nephrotic: two patterns of injury
Doctors often describe glomerular disease by which of two patterns it produces. The distinction guides how urgently to act and which diagnoses to consider — and it’s a question patients ask constantly, so it’s worth understanding.
| Pattern | What stands out | Often points to |
|---|---|---|
| Nephritic | More blood in the urine (often cola-colored), high blood pressure, a modest amount of protein, sometimes reduced filtering | IgA nephropathy, post-infectious GN, lupus nephritis, vasculitis |
| Nephrotic | Heavy protein loss, very foamy urine, low blood protein, marked swelling (legs, face, around the eyes) | Minimal change disease, FSGS, membranous nephropathy |
In short, the nephritic pattern leans toward inflammation and bleeding, while the nephrotic pattern leans toward heavy protein loss and swelling. Plenty of diseases can cause either pattern — and some cause a mix — which is one more reason that the precise diagnosis, often confirmed by a biopsy, drives the whole treatment plan.
What causes it?
Causes vary widely, and they fall into a few broad groups:
- Immune-driven. The most common thread. The immune system mistakenly attacks the kidney’s filters, as in IgA nephropathy, lupus nephritis, and certain forms of vasculitis.
- Post-infectious. Some forms follow an infection — classically a strep throat or skin infection in children, but also infections of the heart valves, hepatitis, or HIV.
- Part of a systemic disease. Conditions like lupus or diabetes affect the kidneys alongside the rest of the body.
- Inherited. A few forms, such as Alport syndrome, run in families.
- Unknown. In some cases the trigger is never fully identified, and treatment focuses on the injury itself.
Pinning down which category — and which specific disease — you have is the foundation of effective treatment, because the right approach for one cause can be the wrong approach for another.
The common types, briefly
If you’ve been given a specific diagnosis, it helps to see where it fits. Among the most common:
IgA nephropathy
Also called Berger disease — the most common glomerular disease worldwide. A protein called IgA builds up in the filters. It’s the focus of the recent treatment progress below.
Lupus nephritis
Kidney inflammation caused by lupus, an autoimmune disease. Managing it goes hand in hand with managing the lupus itself.
FSGS
Focal segmental glomerulosclerosis — scarring in parts of the filters, and a frequent cause of heavy protein loss (nephrotic-pattern disease).
Membranous nephropathy
Thickening of the filter membrane, often immune-driven, that leads to protein in the urine. Many cases are linked to a specific antibody now used in diagnosis.
Minimal change disease
A leading cause of nephrotic syndrome in children. The filters look nearly normal under a regular microscope yet leak protein heavily — and often respond well to treatment.
Post-infectious GN
Follows an infection such as strep throat, especially in children. It frequently resolves on its own with supportive care as the body recovers.
Each of these is approached differently, which is exactly why getting the precise diagnosis matters so much.
Why diagnosis — and often a biopsy — matters
Because so many glomerular diseases share symptoms but need different treatments, getting the diagnosis right is the single most important step. Evaluation usually builds in layers:
- Urine tests to measure blood and protein, and to look at the cells and casts under a microscope.
- Blood tests for kidney function (eGFR), and often specific antibodies that point to a particular disease — for example, markers of lupus or membranous nephropathy.
- Imaging, usually an ultrasound, to look at the kidneys’ size and structure.
- A kidney biopsy in many cases — a small tissue sample, typically taken with a needle under local anesthesia and ultrasound guidance, then examined under a microscope.
A biopsy can feel intimidating, but it’s often what turns guesswork into precise, effective treatment. It can reveal the exact type of disease, how active the inflammation is, and how much scarring has already occurred — information that directly shapes which medications to use and how aggressively. Your doctor will explain whether you need one and what it involves.
A field that’s changing fast — for the better
Here’s something most patients haven’t heard: glomerular disease — and IgA nephropathy in particular — is in the middle of a genuine treatment revolution. For decades, options were limited to general kidney protection and broad immune-suppressing drugs with significant side effects. That has changed dramatically.
In just the last few years, the first medications developed specifically for IgA nephropathy have been approved, with several more advancing through clinical trials. The national guidelines (KDIGO) were updated in 2025 to keep pace, and they reflect a real shift in thinking:
Start together, not in sequence
Newer guidance favors beginning kidney-protective and disease-specific treatment at the same time for higher-risk patients, rather than trying one, waiting, then adding the next.
Targeted-release budesonide
A form of steroid released in the part of the gut where IgA nephropathy is thought to begin, aiming the treatment at the source while limiting body-wide side effects.
Sparsentan
A dual receptor blocker shown to lower protein in the urine more than older blood-pressure medication alone, helping protect filtering over time.
SGLT2 inhibitors
Originally diabetes drugs, now used to slow kidney decline in many glomerular diseases — benefit that holds up whether or not a person has diabetes.
What this means for patients is real hope: more targeted treatments, aimed at the actual mechanism of the disease, with the goal of protecting kidney function before damage becomes permanent.
It also means that where you’re treated matters. A practice connected to current research can offer access to the newest approaches, including clinical studies. Through the Georgia Nephrology Research Institute, our patients can reach that kind of care.
Want a precise diagnosis and access to the newest glomerular treatments?
Request an AppointmentHow is it treated?
Treatment depends entirely on the type, cause, and activity of the disease — but most plans combine two layers: protecting the kidney generally, and targeting the specific disease. Depending on your diagnosis, that may include:
- Kidney-protective foundation — careful blood pressure control (often with an ACE inhibitor or ARB), medications that reduce protein loss, and increasingly SGLT2 inhibitors to slow decline.
- Disease-specific therapy — for active immune-driven disease, this can mean immune-modulating medication or, for IgA nephropathy, one of the newer targeted treatments above. For lupus nephritis, it’s coordinated with treating the lupus.
- Managing the consequences — controlling swelling, blood pressure, and cholesterol, and watching for clotting risk when protein loss is heavy.
- Access to newer therapies and clinical trials for eligible patients.
The aim throughout is to calm the inflammation and preserve as much kidney function as possible — ideally before lasting damage occurs. For the care we provide around these conditions, see our glomerular disease care service.
When should you see a nephrologist?
Glomerular disease is one of the clearest reasons to involve a kidney specialist early, because the right diagnosis and treatment are genuinely specialized. Consider it when:
- A test has shown blood and protein in your urine together
- You have unexplained swelling in the legs, face, or around the eyes
- You’ve developed high blood pressure that’s new or suddenly hard to control
- You’ve been given a specific glomerular diagnosis and want expert, current treatment
- Your kidney function has dropped quickly — this can be urgent and shouldn’t wait
A few aggressive forms can damage the kidneys over days to weeks, so a fast decline in function, or significant blood and protein in the urine, deserves prompt attention. More often there’s time to act — and acting early, with a precise diagnosis, is what gives these conditions their best outcomes.
