Post-Streptococcal Glomerulonephritis in Children: Clinical Case
Clinical Case of Post-Streptococcal Glomerulonephritis in Children
Clinical Case: Post-Streptococcal Glomerulonephritis in a 7-year-old Boy
A 7-year-old boy, John, is brought to the pediatric clinic by his mother with complaints of facial puffiness, decreased urine output, and tea-colored urine for the past two days. His mother mentions that John had a sore throat and fever about two weeks ago, which resolved on its own.
History:
- No significant past medical history
- No known allergies
- Immunizations up to date
- No family history of kidney disease
Physical Examination:
- Temperature: 37.8°C
- Blood Pressure: 130/85 mmHg (>95th percentile for age and height)
- Heart Rate: 100 beats/min
- Respiratory Rate: 22 breaths/min
- Weight: 26 kg (2 kg increase from last recorded weight 3 months ago)
- Periorbital and facial edema noted
- Mild pedal edema present
- Lungs clear to auscultation
- Heart sounds normal, no murmurs
- Abdomen soft, non-tender, no organomegaly
Laboratory Findings:
- Urinalysis:
- Color: Tea-colored
- Protein: 3+
- Blood: 3+
- RBC: >50/hpf
- WBC: 5-10/hpf
- Serum creatinine: 1.2 mg/dL (elevated for age)
- BUN: 30 mg/dL
- Serum C3 complement: 40 mg/dL (low, normal range 90-180 mg/dL)
- ASO titer: 800 IU/mL (elevated, normal <200 IU/mL)
- Anti-DNase B: 680 U/mL (elevated, normal <170 U/mL)
- Throat culture: Negative for Group A Streptococcus
Diagnosis:
Based on the clinical presentation, recent history of sore throat, laboratory findings (especially low C3 complement and elevated ASO titer), and urinalysis results, a diagnosis of Post-Streptococcal Glomerulonephritis (PSGN) is made.
Management:
- Admission for close monitoring and management
- Fluid and sodium restriction
- Blood pressure control with a calcium channel blocker (Amlodipine)
- Furosemide for edema management
- Penicillin V to eradicate any remaining streptococcal infection
- Daily weight, input/output monitoring
- Serial blood pressure measurements
- Follow-up urinalysis and serum creatinine
Outcome:
John's condition improves over the next 5 days. His edema resolves, urine output normalizes, and blood pressure returns to normal range. He is discharged with follow-up appointments to monitor for complete resolution of symptoms and normalization of laboratory values.
Clinical Presentations of Post-Streptococcal Glomerulonephritis in Children
Five Different Clinical Presentations of PSGN in Children
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Classic Nephritic Syndrome
- Sudden onset of cola-colored or tea-colored urine
- Periorbital and facial edema, often noticed first thing in the morning
- Oliguria (decreased urine output)
- Hypertension
- Mild to moderate peripheral edema
- History of recent streptococcal infection (usually 1-3 weeks prior)
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Hypertensive Emergency
- Severe hypertension (often >99th percentile for age, sex, and height)
- Headache, visual disturbances, or altered mental status
- Seizures in extreme cases
- Posterior reversible encephalopathy syndrome (PRES) may occur
- Other features of PSGN may be present but overshadowed by hypertensive symptoms
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Rapidly Progressive Glomerulonephritis (RPGN)
- Rapid decline in renal function over days to weeks
- Severe oliguria or anuria
- Uremic symptoms: nausea, vomiting, lethargy
- Severe edema and hypertension
- May require dialysis
- More common in older children or adolescents
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Subclinical or Asymptomatic Presentation
- Discovered incidentally during urine screening or family member screening
- Microscopic hematuria with or without proteinuria
- No visible edema or hypertension
- Patient may be unaware of recent streptococcal infection
- Normal renal function
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Nephrotic-Nephritic Overlap
- Features of both nephritic and nephrotic syndrome
- Significant proteinuria (>40 mg/m²/hour or urine protein/creatinine ratio >2)
- Hypoalbuminemia (<2.5 g/dL)
- Severe edema, including possible ascites or pleural effusions
- Hematuria and hypertension typical of nephritic syndrome
- May have more severe and prolonged course
Viva Questions and Answers on Post-Streptococcal Glomerulonephritis in Children
25 Viva Questions and Answers on PSGN in Children
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Q: What is the typical latency period between streptococcal infection and the onset of PSGN?
A: The typical latency period is 1-3 weeks after a streptococcal throat infection (pharyngitis) and 3-6 weeks after a skin infection (impetigo).
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Q: Which streptococcal M protein serotypes are most commonly associated with PSGN?
A: The most nephritogenic strains are M types 1, 4, 12, 25, 49, and 61. However, this can vary geographically and over time.
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Q: What is the pathogenesis of PSGN?
A: PSGN is an immune complex-mediated disease. Streptococcal antigens form immune complexes with antibodies, which deposit in the glomeruli. This activates complement and induces inflammation, leading to glomerular injury.
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Q: How does the complement system change in acute PSGN?
A: In acute PSGN, there is activation of the alternative complement pathway, leading to low serum C3 levels. C4 levels typically remain normal. C3 levels usually return to normal within 6-8 weeks.
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Q: What are the key urinary findings in PSGN?
A: Key urinary findings include hematuria (often visible), proteinuria (usually <2g/day), and the presence of red blood cell casts.
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Q: How is hypertension managed in children with PSGN?
A: Management includes sodium and fluid restriction. If pharmacological treatment is needed, calcium channel blockers (e.g., amlodipine) or ACE inhibitors are commonly used. In severe cases, IV medications like labetalol may be necessary.
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Q: What is the role of antibiotics in the treatment of PSGN?
A: Antibiotics (usually penicillin) are given to eradicate any remaining streptococcal infection and prevent spread to contacts. However, antibiotics do not alter the course of established PSGN.
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Q: How do you differentiate PSGN from IgA nephropathy in a child with acute nephritic syndrome?
A: While clinical presentation can be similar, PSGN typically has a preceding streptococcal infection, low C3 levels, and elevated ASO titers. IgA nephropathy often has normal complement levels and may have a history of synpharyngitic hematuria.
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Q: What is the significance of persistently low C3 levels in PSGN?
A: Persistently low C3 levels (>8 weeks) suggest an alternative diagnosis, such as membranoproliferative glomerulonephritis or lupus nephritis.
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Q: Describe the typical light microscopy findings in a renal biopsy of acute PSGN.
A: Light microscopy typically shows diffuse endocapillary proliferation with neutrophil infiltration. "Lumpy-bumpy" deposits may be seen along the capillary walls and in the mesangium.
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Q: What are the immunofluorescence findings in PSGN?
A: Immunofluorescence typically shows granular deposits of IgG and C3 along the capillary walls and in the mesangium, often described as a "starry sky" pattern.
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Q: How does electron microscopy contribute to the diagnosis of PSGN?
A: Electron microscopy reveals subepithelial electron-dense deposits known as "humps," which are characteristic of PSGN.
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Q: What is the "nephritis-associated plasmin receptor" (NAPlr) and its significance in PSGN?
A: NAPlr is a streptococcal antigen that has been implicated in the pathogenesis of PSGN. It can be found in the glomeruli of patients with PSGN and may play a role in complement activation and plasmin-mediated tissue injury.
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Q: How does the incidence of PSGN vary globally?
A: PSGN is more common in developing countries and in areas with limited access to healthcare. The incidence has decreased significantly in developed countries due to improved living conditions and early treatment of streptococcal infections.
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Q: What is the typical age distribution for PSGN in children?
A: PSGN is most common in children aged 5-12 years. It is rare in children under 2 years of age and in adults over 40 years.
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Q: How does the presentation of PSGN differ in infants compared to older children?
A: In infants, PSGN may present more subtly. Edema might be the predominant feature, while hematuria may be less noticeable. Hypertension can be more difficult to detect and manage in this age group.
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Q: What are the indications for renal biopsy in suspected PSGN?
A: Renal biopsy is not routinely performed in PSGN. Indications include atypical presentation, persistent nephrotic-range proteinuria, rapidly progressive course, or persistently low C3 levels beyond 8 weeks.
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Q: How do you manage fluid overload in a child with PSGN?
A: Management includes sodium and fluid restriction, loop diuretics (e.g., furosemide), and in severe cases, ultrafiltration or dialysis may be necessary.
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Q: What is the long-term prognosis for children with PSGN?
A: The prognosis is generally excellent in children. Most recover completely within 6-8 weeks. However, a small percentage (<1%) may progress to chronic kidney disease. Long-term follow-up is recommended.
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Q: How does PSGN affect renal function in the acute phase?
A: In the acute phase, there is often a transient decrease in glomerular filtration rate (GFR) due to inflammation and reduced functioning nephrons. This typically resolves as the inflammation subsides.
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Q: What is the significance of anti-streptolysin O (ASO) and anti-DNase B titers in PSGN?
A: Elevated ASO and anti-DNase B titers provide evidence of recent streptococcal infection. ASO rises after throat infections, while anti-DNase B is more sensitive for skin infections. Both can be elevated in PSGN.
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Q: How do you differentiate PSGN from acute interstitial nephritis?
A: While both can present with acute kidney injury and hematuria, PSGN typically has low C3 levels, edema, and hypertension. Acute interstitial nephritis often has normal complement levels, may have eosinophiluria, and is frequently associated with drug exposure.
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Q: What is the role of crescents in PSGN and how do they affect prognosis?
A: Crescents are seen in a minority of PSGN cases (typically <20% of glomeruli). Their presence in a significant proportion of glomeruli (>50%) suggests a more severe disease course and may indicate rapidly progressive glomerulonephritis (RPGN). Extensive crescent formation is associated with a poorer prognosis and may require more aggressive therapy.
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Q: How does PSGN differ from C3 glomerulonephritis?
A: While both can present with low C3 levels, PSGN typically has a clear history of streptococcal infection, normalizes C3 within 6-8 weeks, and has a self-limited course. C3 glomerulonephritis has persistent low C3 levels, no association with streptococcal infection, and often a more chronic course. On immunofluorescence, PSGN shows both IgG and C3 deposits, while C3 glomerulonephritis shows only C3 deposits.
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Q: What preventive measures can be taken to reduce the incidence of PSGN in a community?
A: Preventive measures include:
- Early detection and treatment of streptococcal infections
- Improving access to healthcare in underserved areas
- Public health measures to reduce overcrowding
- Education about proper hygiene practices
- In some high-risk settings, consideration of mass antibiotic prophylaxis during outbreaks
