Glomerulonephritis is kidney inflammation that starts in the glomeruli, the tiny filters that clean blood and make urine. When these filters are irritated or damaged, blood and protein leak into the urine, fluid builds up in the body, blood pressure rises, and kidney function drops.
Some forms appear suddenly after an infection. Others develop quietly over months or years and show up first as foamy urine, high blood pressure, or abnormal lab results. The most important step is not guessing the cause from symptoms alone. Glomerulonephritis is a pattern of kidney injury, not one single disease, and the right treatment depends on the exact type.
Table of Contents
- What Glomerulonephritis Means
- Symptoms and Warning Signs
- Main Causes and Types
- How Doctors Test for It
- Treatment Options
- Recovery, Monitoring, and Long-Term Care
- When to Seek Urgent Care
What Glomerulonephritis Means
Glomerulonephritis means inflammation of the kidney’s filtering units. Each kidney contains many tiny filters called glomeruli. These filters keep blood cells and important proteins in the bloodstream while removing extra water, salt, and waste into the urine.
When glomeruli are inflamed, the filter becomes leaky and less efficient. Red blood cells slip into the urine. Protein, especially albumin, leaks out. Salt and fluid stay in the body instead of leaving through urine. Waste products such as creatinine build up when filtering slows.
This is why glomerulonephritis often causes a mix of urine changes, swelling, high blood pressure, and abnormal kidney blood tests. A person does not need to feel kidney pain to have it. In fact, many cases are found because a routine urine test shows blood or protein.
Doctors often describe glomerulonephritis as either acute or chronic. Acute glomerulonephritis comes on quickly, sometimes over days or weeks. Chronic glomerulonephritis lasts longer and often progresses slowly. Some types flare and settle down, while others cause steady damage without obvious symptoms.
Another useful distinction is nephritic versus nephrotic patterns. A nephritic pattern usually features blood in the urine, high blood pressure, reduced kidney function, and sometimes red blood cell casts seen under a microscope. A nephrotic pattern features heavy protein loss, very foamy urine, low blood albumin, and swelling. Many real cases overlap, which is why testing matters.
Protein leakage is one of the most important clues. Small amounts of albumin in urine deserve follow-up because they show filter stress early; a detailed guide to albumin in urine explains why even mild leakage matters for kidney health.
Symptoms and Warning Signs
The classic signs are blood in the urine, foamy urine, swelling, and high blood pressure. The exact mix depends on how fast the inflammation develops and how much filtering capacity is affected.
Urine changes are often the first thing people notice. Blood from glomerulonephritis usually does not look bright red like bleeding from a bladder infection or stone. It often looks tea-colored, cola-colored, smoky, or rusty because the blood has passed through the kidney filters. Some people see no color change at all, but a urine test shows microscopic blood.
Foamy urine points toward protein leakage. A few bubbles after urinating are common and harmless, especially with fast urine flow. Persistent foam that looks like a layer of soap suds, returns repeatedly, or appears with swelling deserves testing. More detail on what counts as concerning is covered in foamy urine and protein.
Swelling often appears around the eyes in the morning and in the ankles or feet later in the day. Rings may feel tight. Shoes may leave deeper marks. Weight can rise quickly from fluid, not fat. In children, parents sometimes notice puffy eyelids before any other symptom.
High blood pressure is common because injured kidneys hold onto salt and water and activate hormone systems that tighten blood vessels. Some people feel headaches, shortness of breath, or chest pressure when blood pressure is very high. Others feel normal even with dangerous readings.
Fatigue, nausea, loss of appetite, and reduced urination suggest kidney function has dropped. These symptoms are not specific, but they become more concerning when they appear with dark urine, swelling, or abnormal lab results.
| Sign | What it often means | What to do next |
|---|---|---|
| Tea, cola, or rusty urine | Blood coming from the kidney filters | Get urinalysis and kidney blood tests promptly |
| Persistent foamy urine | Protein leaking into urine | Ask for urine albumin-creatinine or protein-creatinine testing |
| Puffy eyes or swollen ankles | Salt and fluid retention, sometimes low blood albumin | Check blood pressure, kidney function, and urine protein |
| High blood pressure | Kidney inflammation affecting fluid and hormone balance | Arrange medical evaluation, especially with urine changes |
| Very low urine output | Possible acute kidney injury | Seek urgent care |
Glomerulonephritis is different from a typical UTI. UTIs usually cause burning, urgency, frequent small urination, and sometimes lower belly pain. Glomerulonephritis more often causes blood or protein in urine without burning. A person can have both, but a positive urine blood result should not automatically be blamed on infection without looking at protein, kidney function, and urine microscopy. For a broader comparison of urine blood causes, see blood in urine warning signs.
Main Causes and Types
Glomerulonephritis happens when the immune system, an infection, an inherited condition, or another disease injures the glomeruli. The immune system is involved in many cases, but that does not mean every case is “autoimmune” in the same way.
IgA nephropathy
IgA nephropathy is one of the most common glomerular diseases worldwide. IgA is an immune protein that normally helps protect mucous membranes, such as the nose, throat, and gut. In IgA nephropathy, abnormal IgA deposits collect in the kidney filters and trigger inflammation.
A common clue is blood in the urine during or shortly after a cold, sore throat, or stomach infection. Some people have repeated episodes of cola-colored urine. Others never see visible blood and are diagnosed after routine urine testing shows microscopic blood and protein. The amount of protein in urine and the trend in kidney function strongly influence treatment decisions. A full topic page on IgA nephropathy covers this condition in more detail.
Postinfectious glomerulonephritis
Postinfectious glomerulonephritis appears after an infection triggers immune activity that affects the kidneys. The classic example follows strep throat or a skin infection, especially in children, but other bacterial, viral, and deep-seated infections also trigger it.
The timing helps. Kidney symptoms often start one to several weeks after the infection, not usually during the first day of a sore throat. A child may recover from a skin infection, then develop puffy eyes, dark urine, and high blood pressure. Treatment focuses on controlling blood pressure and fluid while treating any active infection.
Lupus nephritis
Lupus nephritis occurs when systemic lupus erythematosus affects the kidneys. Lupus is an autoimmune disease that involves many body systems, including skin, joints, blood cells, and kidneys. Kidney involvement sometimes appears without dramatic kidney symptoms, which is why people with lupus need regular urine and blood monitoring.
The urine may show blood, protein, or both. Treatment depends heavily on biopsy class because some patterns need intensive immune treatment, while others need supportive kidney protection and monitoring. More practical detail is available in lupus nephritis testing and treatment.
ANCA-associated vasculitis and anti-GBM disease
ANCA-associated vasculitis is an autoimmune blood vessel inflammation that often affects the kidneys and sometimes the lungs, sinuses, nerves, or skin. Kidney involvement can move quickly. Warning signs include rapidly rising creatinine, blood and protein in urine, cough with blood, shortness of breath, sinus disease, rash, or nerve symptoms.
Anti-GBM disease is less common but often more urgent. In this condition, antibodies attack a structure in the kidney filter called the glomerular basement membrane. Some people also develop lung bleeding. Rapid diagnosis matters because treatment is most effective before severe scarring develops.
Inherited and chronic causes
Some glomerular problems run in families. Alport syndrome is an inherited condition that affects collagen in the kidney filter and may also involve hearing and eye findings. Thin basement membrane disease often causes persistent microscopic blood in urine and is usually milder, though family history still matters.
Other conditions associated with glomerular disease include hepatitis B, hepatitis C, HIV, endocarditis, certain cancers, and medication-related immune reactions. Diabetes and high blood pressure also damage kidney filters, though doctors usually describe those as diabetic kidney disease or hypertensive kidney disease rather than classic glomerulonephritis.
How Doctors Test for It
Testing starts with urine and blood, then narrows the cause with immune tests and sometimes a kidney biopsy. Symptoms alone cannot separate IgA nephropathy from lupus nephritis, postinfectious disease, ANCA vasculitis, or anti-GBM disease.
A urinalysis checks for blood, protein, white blood cells, and casts. Casts are tiny tube-shaped particles formed inside kidney tubules. Red blood cell casts strongly suggest bleeding from inside the kidney rather than from the bladder, prostate, urethra, or menstruation.
Urine protein testing measures how much protein is leaking. A dipstick gives a rough estimate, but doctors usually confirm with an albumin-creatinine ratio or protein-creatinine ratio from a spot urine sample. Some cases need a 24-hour urine collection. Persistent or heavy protein leakage affects both diagnosis and treatment intensity; a practical overview of protein in urine explains the key test differences.
Blood tests show how well the kidneys are filtering. Creatinine is used to estimate eGFR, or estimated glomerular filtration rate. A rising creatinine over days or weeks is more urgent than a stable mildly abnormal result. BUN, electrolytes, bicarbonate, albumin, cholesterol, and blood counts give additional clues about fluid balance, kidney performance, inflammation, and protein loss. If creatinine terminology is confusing, BUN and creatinine testing breaks down what these labs mean.
Doctors then order targeted tests based on the story and urine findings. These often include complement levels, ANA, anti-dsDNA, ANCA, anti-GBM antibodies, hepatitis B and C tests, HIV testing, strep antibody tests, and sometimes blood cultures if a deep infection is possible.
Kidney ultrasound is often used to check kidney size, blockage, cysts, stones, and structural problems. Ultrasound does not diagnose most types of glomerulonephritis, but it helps rule out other causes of kidney dysfunction and guides biopsy planning.
A kidney biopsy is often the test that gives the most specific answer. During a biopsy, a doctor uses imaging guidance to remove a tiny piece of kidney tissue with a needle. A pathologist studies the sample under different microscopes and looks for immune deposits, scarring, crescents, and patterns that identify the disease type. Biopsy results help doctors choose between observation, blood pressure treatment, steroids, stronger immune therapy, or urgent hospital treatment. The procedure, risks, and result terms are explained in more depth in kidney biopsy results.
Not every person needs a biopsy. A child with a classic post-strep pattern that improves quickly may be monitored without one. Someone with mild stable urine findings and normal kidney function may also be followed closely. A biopsy becomes more likely when kidney function worsens, protein levels are high, urine findings persist, autoimmune blood tests are positive, or the diagnosis is unclear.
Treatment Options
Treatment has two goals: protect the kidneys from ongoing damage and treat the specific cause of inflammation. The plan changes based on diagnosis, severity, kidney function, protein level, blood pressure, age, infection risk, pregnancy status, and biopsy findings.
Supportive kidney protection
Nearly every treatment plan includes supportive care. This is not “minor” treatment; it is the foundation that lowers pressure inside the kidney filters and reduces long-term scarring.
Blood pressure control is central. Many people need a target lower than the usual office threshold because protein leakage and kidney inflammation raise future kidney risk. ACE inhibitors or ARBs are commonly used when protein is present because they lower blood pressure and reduce protein leakage through the glomeruli. These medicines require potassium and creatinine monitoring after starting or changing the dose. The relationship between pressure and kidney damage is explained further in high blood pressure and kidney disease.
Salt restriction helps swelling and blood pressure. A practical target is avoiding heavily salted packaged foods, restaurant soups, processed meats, salty snacks, and large portions of cheese or sauces. Severe swelling sometimes requires a diuretic, often called a water pill, to remove extra fluid.
Protein intake should be reasonable, not extreme. Very high-protein diets increase the filtering workload in people with kidney disease. On the other hand, overly strict protein restriction without guidance leads to poor nutrition, especially when urine protein losses are heavy. A kidney dietitian is useful when proteinuria, reduced eGFR, swelling, high potassium, or high phosphorus complicates meal planning.
SGLT2 inhibitors are now part of kidney-protective care for many people with chronic kidney disease and albuminuria, with or without diabetes, when eGFR and clinical factors fit. They are not a substitute for treating active immune inflammation, but they lower long-term kidney risk in selected patients.
Treating the trigger or immune disease
Postinfectious glomerulonephritis treatment focuses on treating any active infection and controlling fluid, blood pressure, and kidney complications while inflammation settles. Antibiotics treat ongoing bacterial infection; they do not instantly reverse kidney inflammation that has already been triggered.
Lupus nephritis often requires immune treatment such as glucocorticoids plus medicines like mycophenolate, cyclophosphamide, belimumab, voclosporin, or other specialist-directed regimens. The exact choice depends on biopsy class, severity, fertility considerations, infection risk, cost, and medication access.
ANCA-associated vasculitis usually needs prompt immune treatment, often with glucocorticoids plus rituximab or cyclophosphamide. Some patients are candidates for avacopan, a targeted complement pathway medicine that reduces steroid exposure in selected cases. Severe disease with lung bleeding or advanced kidney involvement may require hospital care.
Anti-GBM disease is treated urgently, often with plasma exchange, glucocorticoids, and cyclophosphamide. Plasma exchange removes harmful antibodies from the blood. Timing is critical because kidney recovery is much harder once extensive scarring or prolonged dialysis dependence develops.
IgA nephropathy treatment starts with optimized supportive care, especially blood pressure and proteinuria reduction. Some higher-risk cases need targeted-release budesonide, systemic steroids, or other specialist treatments. The decision depends on protein level, eGFR, biopsy features, and how much risk remains after supportive care.
Treating complications
Severe swelling, very high blood pressure, high potassium, fluid in the lungs, or severe acid buildup needs rapid treatment. Some people with acute kidney injury need temporary dialysis while the kidneys recover or while immune treatment takes effect. Others progress to chronic kidney failure and need long-term planning for dialysis, transplant evaluation, or supportive kidney care.
Doctors also watch for treatment side effects. Steroids raise blood sugar, blood pressure, infection risk, mood changes, and bone loss. Cyclophosphamide affects fertility and bladder risk. Rituximab lowers certain immune defenses. Mycophenolate is not safe in pregnancy. These risks do not mean the drugs should be avoided when disease is serious; they mean monitoring and prevention must be built into the plan.
Recovery, Monitoring, and Long-Term Care
Recovery depends on the cause, how quickly treatment starts, how much scarring is present, and whether proteinuria and blood pressure come under control. Some postinfectious cases recover fully. Some IgA nephropathy cases stay stable for decades. Rapidly progressive forms cause permanent kidney damage if treatment is delayed.
Follow-up is usually based on trends, not one lab value. Doctors watch urine protein, urine blood, creatinine, eGFR, potassium, bicarbonate, albumin, blood pressure, weight, and symptoms. A falling urine protein level is a good sign. A stable eGFR is reassuring. Rising creatinine, increasing protein, or returning blood in urine needs reassessment.
Home blood pressure readings are often more useful than a single clinic number. A simple log should include the date, time, reading, pulse, and any notes about missed medicines, swelling, illness, or unusually salty meals. Bring the cuff to a clinic visit once to confirm it reads accurately.
Daily weights help when swelling is active. Weigh at the same time each morning after urinating and before eating. A sudden gain over a few days often means fluid retention. This is especially important if swelling, shortness of breath, or high blood pressure is part of the picture.
Medication safety matters. Avoid nonsteroidal anti-inflammatory drugs such as ibuprofen and naproxen unless a clinician who knows your kidney status approves them. These drugs reduce blood flow inside the kidney and worsen fluid retention in vulnerable patients. Check before using herbal supplements, bodybuilding supplements, high-dose vitamin C, or “kidney cleanse” products. Natural does not mean kidney-safe.
Vaccines, infection prevention, bone protection, stomach protection, and reproductive planning become important when immune-suppressing medicines are used. People taking strong immune treatment should ask which vaccines are recommended, which live vaccines to avoid, what infection symptoms need same-day advice, and how treatment affects pregnancy plans.
Long-term kidney protection also includes managing diabetes, cholesterol, smoking, sleep apnea, and heart disease risk. Glomerulonephritis is a kidney condition, but the heart and blood vessels are closely tied to kidney outcomes. Good blood pressure control, less sodium, regular movement within personal limits, and medication consistency reduce the risk of both kidney decline and cardiovascular events.
When to Seek Urgent Care
Some glomerulonephritis patterns are medical emergencies. Do not wait for a routine appointment if symptoms point to rapidly worsening kidney function, severe fluid overload, or lung involvement.
Seek urgent care now for:
- Very low urine output or no urine
- Dark cola-colored urine with swelling or high blood pressure
- Shortness of breath, chest pressure, or coughing blood
- Severe headache, confusion, weakness, or vision changes with high blood pressure
- Rapid weight gain with swollen legs, puffy face, or trouble breathing lying flat
- Known kidney disease with rising creatinine, high potassium, or worsening swelling
- Blood in urine plus fever, rash, joint swelling, sinus bleeding, or unexplained fatigue
A same-week medical visit is appropriate for persistent foamy urine, repeated microscopic blood in urine, new high blood pressure, mild swelling, or abnormal kidney labs found on routine testing. These signs are not always emergencies, but they should not be ignored.
Before the visit, write down recent infections, sore throat, skin infections, new medicines, supplements, autoimmune symptoms, family history of kidney disease, hearing problems, rashes, joint pain, and any episodes of dark urine. Bring recent lab results if you have them. The pattern over time often tells the story faster than a single test.
The main mistake is treating glomerulonephritis as a simple urine problem. Burning and urgency point toward the bladder or urethra. Dark urine, protein, swelling, high blood pressure, or reduced kidney function point higher up, toward the kidney filters. That distinction changes the urgency, testing, specialist referral, and treatment.
References
- KDIGO 2021 Clinical Practice Guideline for the Management of Glomerular Diseases 2021 (Guideline)
- KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease 2024 (Guideline)
- KDIGO 2024 Clinical Practice Guideline for the management of LUPUS NEPHRITIS 2024 (Guideline)
- KDIGO 2024 Clinical Practice Guideline for the Management of Antineutrophil Cytoplasmic Antibody (ANCA)-Associated Vasculitis 2024 (Guideline)
- KDIGO 2025 Clinical Practice Guideline for the Management of Immunoglobulin A Nephropathy (IgAN) and Immunoglobulin A Vasculitis (IgAV) 2025 (Guideline)
- Glomerulonephritis 2023 (Review)
Disclaimer
This article is for education and does not diagnose the cause of blood, protein, swelling, or abnormal kidney tests. Glomerulonephritis includes mild, chronic, and rapidly progressive diseases that require different treatment. A doctor or nephrologist should interpret urine results, kidney function, blood pressure, immune tests, and biopsy findings before treatment decisions are made.
