Glomerulonephritis

What is glomerulonephritis?

Glomerulonephritis is a group of kidney diseases in which the glomeruli — the tiny filtering units inside the kidneys — become inflamed. Each kidney contains roughly a million glomeruli, which work like microscopic sieves that clean waste products and extra fluid from the blood while keeping useful substances, such as protein and blood cells, in the body. When the glomeruli are inflamed, they can leak protein and blood into the urine and may lose their ability to filter waste properly. If you have wondered what is glomerulonephritis in simple terms, it may help to think of it as damage to the kidney’s filters caused, in most cases, by a problem with the immune system.

Glomerulonephritis can be acute (developing suddenly, over days or weeks) or chronic (developing slowly over months or years, sometimes without obvious symptoms for a long time). It can occur on its own, as a primary kidney disease, or as part of a broader illness affecting other organs, such as lupus, diabetes, or certain infections. The ICD-10 code N05.9 refers to unspecified nephritic syndrome, a label doctors may use when the exact type of glomerulonephritis has not yet been determined.

The condition can affect people of any age, including children. Some forms, such as glomerulonephritis following a streptococcal throat or skin infection, are more common in children and young adults, while other forms appear more often in middle-aged or older adults. In hospital settings, glomerulonephritis is usually managed by nephrology departments — the medical specialty focused on kidney disease. At Acibadem, for example, evaluation and treatment of glomerulonephritis is handled within the nephrology specialty, often in cooperation with rheumatology and pathology when an underlying immune condition is suspected.

Symptoms of glomerulonephritis

Glomerulonephritis symptoms vary widely. Some people have dramatic, sudden changes in their urine and blood pressure; others feel entirely well and learn of the condition only when a routine urine or blood test shows an abnormality. Common signs and symptoms include:

• Blood in the urine (hematuria): urine may look pink, red, or brown, like tea or cola. Sometimes the blood is visible only under a microscope.
• Foamy or bubbly urine: often a sign of excess protein in the urine, called proteinuria.
• Swelling (edema): puffiness around the eyes, especially in the morning, and swelling of the ankles, feet, legs, or abdomen caused by fluid retention.
• High blood pressure (hypertension): which may be newly discovered or may worsen if already present.
• Reduced urine output: passing less urine than usual.
• Fatigue and weakness: often related to anemia (low red blood cell count) or the buildup of waste products in the blood.
• Nausea, loss of appetite, or itching: which can occur when kidney function is significantly reduced.

How symptoms appear often depends on the type and stage of the disease. In acute glomerulonephritis — for example, the form that can follow a strep infection — symptoms tend to come on quickly, with visibly dark urine, facial swelling, and elevated blood pressure. In chronic glomerulonephritis, the process is usually silent at first; symptoms such as fatigue, nighttime urination, and gradually worsening swelling may only appear after considerable kidney function has been lost. Some types cause a pattern doctors call nephrotic syndrome, marked by heavy protein loss in the urine, low protein levels in the blood, marked swelling, and high cholesterol. Others cause a nephritic pattern, with blood in the urine, high blood pressure, and reduced urine output. A small number of people develop rapidly progressive glomerulonephritis, in which kidney function declines over days to weeks — this is a medical emergency requiring urgent care.

Because early glomerulonephritis often causes no symptoms at all, abnormal findings on a routine urine test are sometimes the first and only clue. This is one reason doctors take unexplained protein or blood in the urine seriously, even in a person who feels well.

Causes and risk factors

In many cases, glomerulonephritis is caused by a problem with the immune system, in which antibodies or immune complexes (clumps of antibodies bound to other proteins) become trapped in the glomeruli and trigger inflammation. Glomerulonephritis causes fall into several broad groups:

• Infections: glomerulonephritis can follow a streptococcal throat or skin infection (post-streptococcal glomerulonephritis). Other infections associated with glomerular disease include hepatitis B, hepatitis C, HIV, and infections of the heart valves (bacterial endocarditis).
• Autoimmune diseases: conditions in which the immune system attacks the body’s own tissues, such as systemic lupus erythematosus (lupus), IgA nephropathy (a common form in which an antibody called immunoglobulin A deposits in the glomeruli), and Goodpasture syndrome, a rare disease affecting the kidneys and lungs.
• Vasculitis: inflammation of blood vessels, including conditions such as ANCA-associated vasculitis, which can injure the small vessels within the glomeruli.
• Other diseases that scar the glomeruli: long-standing diabetes and poorly controlled high blood pressure damage the kidneys’ filters over time, and certain inherited conditions, such as Alport syndrome, affect the structure of the glomerular filter itself.
• Unknown causes: in a significant number of people, no clear trigger is ever identified. Doctors call this idiopathic glomerulonephritis.

Risk factors depend on the underlying cause, but factors that may increase the likelihood of developing glomerular disease include a recent untreated strep infection, a personal or family history of autoimmune disease or kidney disease, chronic viral infections such as hepatitis, long-standing diabetes or high blood pressure, and exposure to certain medications or solvents in some rare forms. Glomerulonephritis is not contagious, and it is usually not something a person caused through lifestyle alone, although controlling blood pressure and blood sugar can influence how the disease progresses.

Diagnosis

Glomerulonephritis diagnosis begins with a careful medical history and physical examination. Your doctor will ask about recent infections, changes in your urine, swelling, family history of kidney disease, and symptoms of autoimmune conditions such as joint pain or rashes. Blood pressure measurement is an essential part of the examination.

Tests commonly used to confirm and characterize glomerulonephritis include:

• Urinalysis: a urine test that detects blood, protein, and abnormal structures called red blood cell casts, which strongly suggest inflammation within the glomeruli.
• Urine protein quantification: a 24-hour urine collection or a spot urine protein-to-creatinine ratio measures how much protein the kidneys are leaking.
• Blood tests: serum creatinine and estimated glomerular filtration rate (eGFR) assess how well the kidneys are filtering. Additional blood tests may look for low complement levels (proteins consumed during immune reactions), antibodies associated with lupus or vasculitis, evidence of a recent strep infection, and hepatitis or HIV infection.
• Imaging: an ultrasound of the kidneys checks their size and structure and helps rule out other causes of kidney problems, such as blockages. Small, shrunken kidneys may suggest long-standing chronic disease.
• Kidney biopsy: in many cases, the definitive test. A doctor removes a tiny sample of kidney tissue with a needle, usually under local anesthesia and ultrasound guidance. A pathologist then examines the tissue under specialized microscopes to identify the exact type of glomerulonephritis, how active the inflammation is, and how much permanent scarring is present. This information often guides treatment decisions directly.

Not everyone needs a biopsy. For example, in a child with classic post-streptococcal glomerulonephritis that is improving on its own, doctors may reasonably observe without a biopsy. But when the diagnosis is unclear, when kidney function is declining, or when treatment with strong immune-suppressing medication is being considered, a biopsy is often recommended.

Treatment options

Glomerulonephritis treatment depends on the type of disease, its cause, how active it is, and how much kidney function has already been affected. There is no single treatment that fits everyone, and your care team will tailor the approach to your situation. The main options include:

Watchful waiting and supportive care

Some forms of glomerulonephritis, particularly acute post-infectious glomerulonephritis, often improve on their own, especially in children. In these cases, treatment may focus on supportive measures while the kidneys recover: controlling blood pressure, managing swelling, and monitoring kidney function with regular tests. Mild chronic forms with little protein in the urine and stable kidney function may also be monitored without immune-suppressing drugs.

Medications

• Blood pressure medicines: drugs called ACE inhibitors or angiotensin receptor blockers (ARBs) are often used because they both lower blood pressure and reduce protein leakage from the glomeruli, which may help protect the kidneys over time.
• Diuretics: “water pills” that help the body remove excess fluid and reduce swelling.
• Corticosteroids: such as prednisone, which reduce inflammation and dampen the immune attack on the glomeruli in many immune-mediated forms.
• Other immunosuppressive drugs: medications such as cyclophosphamide, mycophenolate, calcineurin inhibitors, or rituximab may be used in more aggressive or steroid-resistant disease. These drugs carry significant potential side effects, including increased risk of infection, so doctors weigh benefits and risks carefully for each patient.
• Antibiotics or antiviral treatment: when an active infection is driving the kidney disease, treating the infection is a central part of therapy.
• Cholesterol-lowering medicines and blood thinners: sometimes used in nephrotic syndrome, which can raise cholesterol levels and the risk of blood clots.

Procedures

In certain severe forms — for example, Goodpasture syndrome or some rapidly progressive types — doctors may use plasmapheresis (plasma exchange), a procedure that filters harmful antibodies out of the blood. If kidney function fails despite treatment, dialysis (a treatment that filters the blood mechanically) may be needed, either temporarily during a severe acute episode or long-term if the kidneys do not recover.

Surgery

Surgery is not a treatment for glomerulonephritis itself. However, if the disease progresses to end-stage kidney failure, kidney transplantation may be considered. A transplant can restore kidney function, though some types of glomerulonephritis can recur in a transplanted kidney, which is one of the factors transplant teams discuss with patients beforehand.

Lifestyle and dietary measures

Alongside medical treatment, doctors often recommend limiting salt to help control blood pressure and swelling, moderating protein intake in some situations, avoiding nonsteroidal anti-inflammatory drugs (NSAIDs, such as ibuprofen) that can strain the kidneys, not smoking, and keeping blood sugar well controlled in people with diabetes. These measures support the kidneys but do not replace prescribed treatment.

Living with glomerulonephritis and outlook

The outlook for glomerulonephritis varies considerably by type. Some forms, such as post-streptococcal glomerulonephritis in children, resolve completely in most cases. Others, such as IgA nephropathy, may remain stable for many years in some people while progressing slowly in others. A minority of patients, particularly those with rapidly progressive forms or long delays in diagnosis, may develop chronic kidney disease or kidney failure. Because outcomes differ so much, your nephrologist is the best source of information about your individual prognosis; no general article can predict how the disease will behave in a particular person.

Living well with glomerulonephritis usually involves regular follow-up appointments with urine and blood tests to track kidney function, consistent blood pressure control, taking medications exactly as prescribed, and promptly reporting new symptoms such as increased swelling or changes in urine. Many people with well-managed glomerulonephritis continue to work, exercise, travel, and live full lives. If the disease does progress, treatments such as dialysis and transplantation exist, and care teams typically plan for these possibilities well in advance rather than in a crisis. Emotional support matters too: a chronic kidney diagnosis can be stressful, and discussing concerns openly with your care team, family, or a counselor is often helpful.

Frequently asked questions

What is glomerulonephritis in simple terms?

Glomerulonephritis is inflammation of the kidneys’ tiny filters, called glomeruli. When these filters are inflamed, they can leak blood and protein into the urine and may struggle to clean waste from the blood. It is usually related to the immune system and can be triggered by infections, autoimmune diseases, or other conditions, though in some people no cause is found.

Can glomerulonephritis heal on its own?

Some forms can. Acute glomerulonephritis after a strep infection, for instance, often resolves without specific treatment, particularly in children. Other forms are chronic and require ongoing management rather than a one-time cure. Only a doctor, often with the help of blood tests, urine tests, and sometimes a kidney biopsy, can determine which type you have and whether it is likely to improve on its own.

How serious is glomerulonephritis?

Seriousness ranges widely. Mild forms may never significantly affect kidney function, while aggressive forms can lead to kidney failure if untreated. Rapidly progressive glomerulonephritis, in which kidney function declines over days to weeks, is a medical emergency. Early diagnosis and appropriate glomerulonephritis treatment generally improve the chances of preserving kidney function, which is why abnormal urine findings should not be ignored even when you feel well.

What are the first signs of glomerulonephritis?

Early glomerulonephritis symptoms often include dark, pink, or cola-colored urine, foamy urine, puffiness around the eyes or ankles, and elevated blood pressure. However, many people have no symptoms at first, and the condition is discovered only through a routine urine test showing blood or protein. Fatigue and reduced urine output can appear as kidney function declines.

How do doctors confirm a glomerulonephritis diagnosis?

Doctors typically start with urine tests looking for blood, protein, and red blood cell casts, along with blood tests measuring kidney function and markers of immune activity. An ultrasound checks the kidneys’ size and structure. In many cases, a kidney biopsy — removing a tiny tissue sample with a needle — is needed to identify the exact type of glomerulonephritis and guide treatment.

Can glomerulonephritis come back after treatment?

Yes, some types can relapse after a period of improvement, and certain forms can even recur in a transplanted kidney. This is one reason long-term follow-up with regular urine and blood tests is usually recommended, even when you feel well and test results have been normal for some time. Your doctor can explain the relapse risk associated with your specific type.

What should I eat if I have glomerulonephritis?

Dietary advice depends on your kidney function, blood pressure, and the amount of protein you are losing in urine. Doctors commonly recommend limiting salt to help control blood pressure and swelling. Some people may be advised to moderate protein, potassium, or fluid intake, but these restrictions are individualized. It is best to follow the guidance of your nephrologist or a renal dietitian rather than general internet advice.

When to see a doctor

See a doctor promptly if you notice possible signs of glomerulonephritis, such as pink, red, brown, or persistently foamy urine, new or worsening swelling of the face, legs, or abdomen, or unexplained high blood pressure — especially within a few weeks after a throat or skin infection. If you have already been diagnosed, contact your care team whenever your symptoms change or worsen. At Acibadem and similar hospital settings, these evaluations are typically coordinated through the nephrology department.

Seek urgent medical care if you experience any of the following red-flag warning signs:

• Passing very little or no urine over several hours or more.
• Sudden, severe swelling of the legs, abdomen, or face.
• Shortness of breath or difficulty breathing when lying down, which can indicate fluid building up in the lungs.
• Severe headache, visual changes, confusion, or seizures, which may signal dangerously high blood pressure.
• Coughing up blood, which in rare conditions can accompany rapidly worsening kidney disease.
• Chest pain or irregular heartbeat, which can occur when waste products or potassium accumulate in the blood.
• High fever with dark urine, particularly if you are taking immune-suppressing medication, since infections can be more serious in that setting.

These symptoms can indicate rapidly declining kidney function or serious complications and should be evaluated without delay. Early medical attention gives the best chance of protecting your kidneys and overall health.