Introduction
Post Infectious Glomerulonephritis (PIGN) is a kidney disorder that develops after certain infections, most commonly bacterial infections. It is characterized by inflammation of the glomeruli—the tiny filtering units inside the kidneys responsible for removing waste and excess fluid from the blood. When these filters become inflamed, kidney function is temporarily impaired, leading to symptoms such as swelling, reduced urine output, and changes in urine color.
Although PIGN is often associated with children following throat or skin infections, it can affect individuals of any age. The condition typically appears one to three weeks after the initial infection. In most children, recovery is complete with supportive care, while adults may experience a more complicated course.
This article provides a comprehensive and simplified explanation of post infectious glomerulonephritis, covering causes, pathophysiology, clinical features, diagnosis, treatment, diet, complications, and prevention.
Understanding the Glomerulus
Each kidney contains about one million glomeruli. These microscopic structures act as filtration units. Blood flows into the glomerulus under pressure, allowing water and small waste products to pass into the urine while retaining essential components like proteins and blood cells.
When inflammation affects the glomerulus, its filtering barrier becomes leaky. As a result:
- Red blood cells may leak into urine (hematuria)
- Protein may appear in urine (proteinuria)
- Salt and water may accumulate in the body
This disruption forms the basis of PIGN.
What Is Post Infectious Glomerulonephritis?
Post Infectious Glomerulonephritis is an immune-mediated kidney inflammation that occurs after an infection. It is not caused by direct invasion of bacteria into the kidney. Instead, the body’s immune response to the infection leads to inflammation in the glomeruli.
Historically, it was most commonly seen after infections caused by Streptococcus bacteria, especially throat infections (pharyngitis) and skin infections (impetigo). However, modern cases can follow infections caused by other bacteria, viruses, and even parasites.
Causes
1. Bacterial Infections
The most common cause is infection with nephritogenic strains of streptococci. These may include:
- Throat infections
- Skin infections
Other bacteria such as staphylococci can also trigger PIGN, especially in adults.
2. Viral Infections
Certain viral illnesses may precede glomerular inflammation.
3. Other Infections
Rarely, fungal and parasitic infections can be implicated.
The kidney inflammation generally begins after the infection has resolved or is improving.
Pathophysiology
The pathogenesis of PIGN is immune-mediated. The key steps include:
- Infection occurs (e.g., throat or skin).
- The immune system produces antibodies against bacterial antigens.
- Antigen-antibody complexes form in circulation.
- These immune complexes deposit in the glomeruli.
- Complement activation occurs, leading to inflammation and injury.
This inflammatory process increases glomerular permeability and reduces filtration efficiency. Complement levels, particularly C3, are often reduced during the active phase of the disease.
Risk Factors
Certain factors increase the likelihood of developing PIGN:
- Recent untreated or partially treated bacterial infection
- Poor hygiene and overcrowded living conditions
- Childhood age group (commonly 5–12 years)
- Weakened immune system
- Chronic illnesses in adults
In developing regions, the incidence remains higher due to recurrent skin and throat infections.
Clinical Features
Symptoms typically appear 1–3 weeks after throat infection and 3–6 weeks after skin infection.
Common Symptoms
1. Hematuria
Urine may appear cola-colored, smoky, or reddish.
2.Edema
Swelling around the eyes (periorbital edema) is common, especially in children. Swelling of legs may also occur.
3.Hypertension
Elevated blood pressure results from fluid retention.
4.Reduced Urine Output
Some patients may pass less urine than usual.
5.Mild Proteinuria
Protein leakage is usually moderate.
6.Fatigue and Malaise
Due to fluid imbalance and inflammation.
Diagnostic Criteria
Diagnosis is based on a combination of clinical history, physical findings, and laboratory investigations.
1. Clinical History
- Recent infection (throat or skin)
- Onset of hematuria and swelling
2. Urine Examination
- Red blood cells
- RBC casts
- Mild to moderate proteinuria
3. Blood Tests
- Elevated serum creatinine (if kidney function is affected)
- Reduced complement levels (especially C3)
- Elevated antistreptococcal antibody titers in relevant cases
4. Imaging
Ultrasound may show enlarged kidneys in acute stages.
5. Kidney Biopsy (Rarely Required)
Performed if diagnosis is uncertain or recovery is delayed. It shows immune complex deposition and glomerular inflammation.
Differential Diagnosis
Conditions that may resemble PIGN include:
- IgA nephropathy
- Lupus nephritis
- Membranoproliferative glomerulonephritis
- Rapidly progressive glomerulonephritis
Distinguishing features and laboratory findings help differentiate these disorders.
Management
Treatment is largely supportive because the condition is self-limiting in most children.
1. Control of Fluid Overload
- Salt restriction
- Fluid restriction
- Diuretics (if needed)
2. Blood Pressure Management
Antihypertensive medications may be required in patients with elevated blood pressure.
3. Treat Underlying Infection
If infection persists, appropriate antibiotics are given. However, antibiotics do not reverse kidney inflammation once it has started; they prevent spread.
4. Monitoring Kidney Function
Regular follow-up with serum creatinine and urine tests is essential.
5. Dialysis (Rare Cases)
Required only if severe kidney failure develops.
Diet in Post Infectious Glomerulonephritis
Dietary modification plays a supportive role.
During Acute Phase
- Low salt diet to reduce swelling and hypertension
- Fluid restriction if urine output is low
- Moderate protein intake (not excessive)
- Avoid processed and packaged foods
After Recovery
- Balanced diet with adequate hydration
- No long-term severe restrictions unless kidney function remains impaired
Complications
Although prognosis is good in children, complications may occur:
- Severe hypertension
- Acute kidney injury
- Pulmonary edema
- Persistent proteinuria
- Chronic kidney disease (rare in children but higher risk in adults)
Adults have a greater likelihood of incomplete recovery compared to children.
Prognosis
In Children
- Most recover completely within weeks to months
- Complement levels normalize within 6–8 weeks
- Hematuria may persist microscopically for months
In Adults
- Recovery may be slower
- Higher risk of persistent hypertension
- Small percentage may progress to chronic kidney disease
Early detection and supportive management significantly improve outcomes.
Prevention
Preventive strategies focus on reducing infections:
- Early treatment of throat and skin infections
- Maintaining personal hygiene
- Avoiding overcrowding
- Proper wound care
- Public health awareness in endemic regions
Timely antibiotic therapy for streptococcal infections reduces transmission but does not always prevent PIGN.
Follow-Up
Patients require periodic monitoring for:
- Blood pressure
- Urine protein
- Kidney function
- Complement levels
Follow-up is especially important in adults and in cases with persistent abnormalities.
When to Seek Immediate Medical Attention
Urgent evaluation is required if the patient develops:
- Severe breathlessness
- Very high blood pressure
- Markedly reduced urine output
- Persistent vomiting
- Seizures
These signs may indicate serious complications.
Conclusion
Post Infectious Glomerulonephritis is an immune-mediated inflammatory kidney condition that typically follows bacterial infections, especially in children. It presents with hematuria, edema, and hypertension and is usually diagnosed through clinical evaluation and laboratory testing. Most pediatric patients recover completely with supportive management, while adults require closer monitoring due to a higher risk of complications.
Early recognition, proper infection control, dietary management, and regular follow-up are essential components of care. With timely intervention and monitoring, the majority of patients experience favorable outcomes.
References (For Further Reading)
- Standard nephrology textbooks
- Peer-reviewed nephrology journals
- Clinical practice guidelines on glomerular diseases
- Public health resources on streptococcal infections
Frequently Asked Questions (FAQs)
What is the main cause of post infectious glomerulonephritis?
It most commonly follows a streptococcal throat or skin infection, though other infections may also trigger it.
Is PIGN contagious?
No. The kidney condition itself is not contagious, but the underlying infection may be.
How long after infection does PIGN appear?
Usually 1–3 weeks after throat infection and 3–6 weeks after skin infection.
Why does urine become dark in PIGN?
Dark or cola-colored urine occurs due to the presence of red blood cells leaking from inflamed glomeruli.
Is kidney biopsy always necessary?
No. Most cases are diagnosed clinically and with laboratory tests. Biopsy is reserved for atypical or prolonged cases.
Can adults develop post infectious glomerulonephritis?
Yes. While common in children, adults can develop it and may have a more severe course.
Does PIGN cause permanent kidney damage?
Most children recover fully. Adults have a higher risk of residual kidney impairment.
What is the role of complement levels in diagnosis?
Low complement levels (especially C3) support the diagnosis during the acute phase.
Are steroids required in treatment?
Generally, no. Treatment is supportive unless there are unusual complications.
How can recurrence be prevented?
Preventing infections through hygiene and early treatment reduces risk, though recurrence is uncommon.