Acute Glomerulonephritis: Causes, Symptoms & Treatment

Acute glomerulonephritis is a serious kidney condition in which the tiny filtering units inside your kidneys — called glomeruli — become rapidly inflamed, impairing their ability to clean waste from your blood. This condition can develop at any age but is most commonly seen in Canadian children between six and ten years old, often following a bacterial or viral infection.

What Causes Acute Glomerulonephritis in Canadian Patients?

Understanding the kidney inflammation causes behind this disease is essential for early detection and timely treatment. In Canada, where access to primary care and nephrology specialists varies by province, knowing the warning signs of glomerulonephritis symptoms can help you seek medical attention faster and protect your long-term kidney health.

What Is Acute Glomerulonephritis?

Common Symptoms of Acute Glomerulonephritis: Description and Severity Guide

Symptom	Description	Severity	When to Seek Care
Hematuria (Blood in Urine)	Urine appears tea-coloured, brown, or pink due to red blood cells leaking through damaged glomeruli	Moderate to Severe	Seek care promptly — visit your family doctor or walk-in clinic within 24–48 hours
Edema (Swelling)	Fluid retention causing puffiness around the eyes, face, ankles, and legs due to reduced kidney filtration	Mild to Severe	See a doctor if swelling is sudden, worsening, or accompanied by difficulty breathing
Hypertension (High Blood Pressure)	Elevated blood pressure resulting from fluid retention and impaired kidney regulation of blood pressure hormones	Moderate to Severe	Go to an emergency department if readings exceed 180/120 mmHg or cause headache or vision changes
Proteinuria (Protein in Urine)	Foamy or frothy urine caused by excess protein escaping through damaged glomerular membranes	Mild to Moderate	Schedule a doctor’s appointment within a few days for urine and blood tests
Oliguria (Reduced Urine Output)	Significantly decreased urine production due to severely impaired kidney filtration capacity	Severe	Seek emergency care immediately — this may indicate acute kidney injury requiring urgent treatment
Fatigue and Malaise	Persistent tiredness and general feeling of illness caused by toxin buildup and systemic inflammation	Mild to Moderate	See a doctor if fatigue is persistent and accompanied by other urinary or swelling symptoms

Your kidneys contain millions of tiny filters called glomeruli. Their job is to remove waste and extra fluid from your blood. When these filters become inflamed, they stop working properly. This is what happens in acute glomerulonephritis.

The inflammation is usually triggered by your immune system reacting to an infection or another disease. Instead of targeting just the infection, your immune system accidentally attacks kidney tissue. As a result, the glomeruli swell, scar, and lose their ability to filter blood effectively.

Acute glomerulonephritis is one of the leading causes of chronic kidney failure worldwide, accounting for about 25% of cases. In children, the condition can have a mortality rate of up to 7% in severe cases. However, most patients — especially children — recover well with proper treatment. Learn more about how the kidneys work at Health Canada’s kidney health resources.

Common Causes of Acute Glomerulonephritis

There are three main groups of causes: post-infectious, systemic diseases, and primary kidney diseases. Each one triggers the immune system in a different way.

Post-Infectious Causes

The most well-known cause is a streptococcal infection — the same bacteria behind strep throat and some skin infections. This is called post-streptococcal glomerulonephritis. It is the most studied form because doctors can clearly identify what triggers the immune reaction.

However, many other infections can also lead to acute glomerulonephritis. These include:

• Bacterial infections: staphylococci, mycobacteria, salmonella, and syphilis (Treponema pallidum)
• Viral infections: hepatitis B, Epstein-Barr virus, cytomegalovirus, and Coxsackie virus
• Parasitic infections: malaria (Plasmodium falciparum or malariae), Schistosoma, and Toxoplasma
• Infections in organs, such as pneumonia, abscesses, or endocarditis (heart valve infection)

Systemic Disease Causes

Some body-wide diseases can also inflame the glomeruli. These conditions affect multiple organs, including the kidneys. Common examples include:

• Lupus (Systemic Lupus Erythematosus): an autoimmune disease that attacks joints, skin, and organs
• Granulomatosis with polyangiitis (formerly Wegener’s granulomatosis): a rare blood vessel disease
• Henoch-Schönlein purpura: a condition causing small blood vessel inflammation, more common in children
• Goodpasture syndrome: a rare autoimmune disease targeting the kidneys and lungs
• Cryoglobulinemia and polyarteritis nodosa: other forms of blood vessel inflammation

In addition, certain medications — including penicillin and gold compounds — have been linked to glomerulonephritis in some patients.

Primary Kidney Disease Causes

Sometimes the problem starts directly within the kidneys themselves. The most common example worldwide is IgA nephropathy, also known as Berger’s disease. In this condition, the immune protein IgA builds up in the glomeruli, causing ongoing inflammation. Other primary causes include membranoproliferative glomerulonephritis and mesangial proliferative glomerulonephritis.

How Acute Glomerulonephritis Affects the Kidneys

When immune complexes — clumps of antibodies and antigens — deposit inside the glomeruli, they trigger a chain reaction. The kidney tissue becomes swollen and filled with inflammatory cells. Under a microscope, doctors can see immune proteins and complement fragments building up inside the filters.

This leads to four key types of damage:

• Cell proliferation: Too many cells grow inside the glomerulus, crowding and thickening the filter walls
• White blood cell buildup: Immune cells flood the area, making inflammation worse
• Thickening of the basement membrane: The walls of the tiny capillaries inside the glomerulus become thick and stiff
• Scarring (sclerosis and hyalinisation): These are permanent, irreversible changes to the kidney tissue

As a result of these changes, the kidneys begin to leak protein and blood into the urine, produce less urine overall, and struggle to control blood pressure. For a deeper look at kidney disease progression, visit the Mayo Clinic’s guide to glomerulonephritis.

Symptoms of Acute Glomerulonephritis

Acute glomerulonephritis tends to come on suddenly, sometimes when a person seems otherwise healthy. The typical patient is a boy between 2 and 14 years old who develops puffy eyes and face following a strep infection. However, adults can be affected too.

Some symptoms are general and easy to miss. These include fatigue, body aches, abdominal pain, fever, and a general feeling of being unwell. However, other signs point more directly to a kidney problem.

Key Kidney-Related Symptoms

• Blood in the urine (haematuria): This affects all patients with acute glomerulonephritis. About 30% notice visibly red or brown urine. The rest have blood found only through urine tests.
• Low urine output (oliguria): The damaged kidneys produce much less urine than normal.
• Swelling (oedema): Puffiness around the eyes and face appears in about 85% of patients, especially children. Swelling in the legs and feet is also common.
• High blood pressure (hypertension): This is very common and can cause headaches, confusion, or disorientation in severe cases.
• Shortness of breath: This appears more often in adults and is caused by fluid building up in the lungs (pulmonary oedema).
• Flank pain: A dull ache on either side of the lower back can occur when the kidney capsule is stretched due to swelling.

Symptoms Linked to Underlying Conditions

When acute glomerulonephritis is caused by a systemic disease, you may notice other symptoms related to that condition. For example:

• Granulomatosis with polyangiitis: sinusitis, lung infiltrates, and kidney inflammation (the classic triad)
• Henoch-Schönlein purpura: nausea, vomiting, abdominal pain, and a purple skin rash (purpura)
• Lupus: joint pain, skin rashes, and fatigue alongside kidney symptoms
• Goodpasture syndrome: coughing up blood (haemoptysis) along with kidney problems

Who Is Most at Risk?

Acute glomerulonephritis can affect people of all ages. However, the post-infectious form — especially the post-streptococcal type — is far more common in children. The highest-risk group is children aged 6 to 10 years old.

Only about 10% of acute glomerulonephritis cases are diagnosed in adults over age 40. Furthermore, in adults, the condition tends to be more severe and less likely to resolve completely on its own. Adults are also more likely to develop complications such as pulmonary oedema and persistent high blood pressure.

People with weakened immune systems, those with a history of frequent strep infections, or those living with autoimmune conditions face a higher overall risk. According to the World Health Organization’s kidney disease fact sheet, kidney diseases affect hundreds of millions of people globally, making early detection critical.

When to See a Doctor

Do not wait if you notice blood in your urine, sudden swelling around your eyes or ankles, or a sharp drop in how much urine you are producing. These are warning signs that need medical attention right away.

If your symptoms come on gradually or seem mild, start by booking an appointment with your family doctor. Your family doctor can order a urine test and blood work to check how well your kidneys are functioning. Most provincial health plans in Canada cover these tests under your health card.

If you do not have a family doctor or cannot get an appointment quickly, visit a walk-in clinic. Walk-in clinics can run initial tests and refer you to a nephrologist (kidney specialist) if needed.

Go to your nearest emergency department immediately if you experience severe shortness of breath, confusion, or very high blood pressure alongside any of the kidney symptoms listed above. These can be signs of a serious complication requiring urgent care.

Always speak with a qualified healthcare provider before drawing any conclusions about your health. Only a doctor can properly diagnose and treat acute glomerulonephritis.

Frequently Asked Questions About Acute Glomerulonephritis

Key Takeaways

• Acute glomerulonephritis is a sudden inflammation of the kidney’s filtering units (glomeruli), often triggered by infections or immune system disorders.
• The most common trigger worldwide is a streptococcal infection, particularly in children aged 6 to 10.
• Main symptoms include blood in the urine, swelling around the eyes and ankles, reduced urine output, and high blood pressure.
• Acute glomerulonephritis is a leading cause of chronic kidney failure, responsible for about 25% of cases.
• Most children recover well with treatment. Adults tend to have more severe outcomes.
• In Canada, your family doctor or walk-in clinic can order the initial tests needed. Provincial health plans cover routine urine and blood work.
• Always consult a healthcare provider if you notice any signs of kidney trouble. Early action protects your long-term kidney health.