What are the disorders under acute glomerulonephritis and their management?

Disorders Under Acute Glomerulonephritis and Their Management

Acute glomerulonephritis encompasses several distinct disorders, with post-streptococcal glomerulonephritis being the most common form, alongside infection-related GN, IgA nephropathy, ANCA-associated vasculitis, anti-GBM disease, lupus nephritis, and C3 glomerulopathy. 1

Primary Categories of Acute Glomerulonephritis

Infection-Related Glomerulonephritis

Post-Streptococcal Glomerulonephritis (PSGN)

• Most common form in developing countries, occurring 1-2 weeks after pharyngitis or 4-6 weeks after impetigo 2, 3
• Immune complex-mediated disease with streptococcal antigen deposition causing glomerular inflammation 2, 4
• Presents with nephritic syndrome: hematuria with RBC casts, proteinuria, hypertension, edema, and reduced kidney function 2, 3
• Hallmark laboratory finding: Low C3 complement with normal C4 2

Bacterial Infection-Related GN

• Three risk categories based on infection source 1:
  • Highest risk: Ventriculo-atrial shunts
  • Mid risk: Ventriculo-jugular shunts
  • Lowest risk: Ventriculo-peritoneal shunts
• Associated with endocarditis, shunt infections, and other chronic bacterial infections 1
• May present with occult infection in 40% of cases 1

Primary Glomerular Disorders

• IgA nephropathy: Characterized by disease flares and asymptomatic hematuria 1, 5
• Membranoproliferative GN (MPGN): Now classified as immunoglobulin- and complement-mediated glomerular diseases with MPGN pattern 1
• C3 glomerulopathy: Including dense deposit disease and C3GN 1, 5

Systemic Immunologic Diseases

• Lupus nephritis: Secondary to systemic lupus erythematosus 1, 3
• ANCA-associated vasculitis: Pauci-immune glomerulonephritis with PR3 or MPO antibodies 1, 5
• Anti-GBM antibody disease: Rapidly progressive glomerulonephritis 1, 5
• IgA vasculitis (Henoch-Schönlein purpura) 1, 3

Management Approach

For Post-Streptococcal Glomerulonephritis

Antimicrobial Therapy

• Administer penicillin (or erythromycin if penicillin-allergic) even without active infection to decrease antigenic load 2
• Use systemic antimicrobials during outbreaks to eliminate nephritogenic Streptococcus pyogenes strains from the community 2
• Cephalosporins are appropriate alternatives: First-generation (cephalexin) for mild cases, third-generation (ceftriaxone) for severe infections 2

Supportive Care

• Restrict sodium intake to <2.0 g/day for hypertension and fluid management 2
• Manage hypertension and fluid overload with diuretics and antihypertensives 2, 6
• Monitor for hyponatremia, hypokalemia, GFR reduction, and volume depletion from diuretics 2
• Treat metabolic acidosis if serum bicarbonate <22 mmol/L 2
• Provide dialysis for severe acute kidney injury 2, 6

Immunosuppression Considerations

• For severe crescentic PSGN: Consider high-dose corticosteroids based on anecdotal evidence only 2, 3
• For most patients with eGFR <30 ml/min per 1.73 m²: Supportive care alone is recommended 2
• Avoid immunosuppression in typical PSGN as the disease is self-limited 3, 7

For Bacterial Infection-Related GN

Diagnostic Workup

• Culture blood, cerebrospinal fluid, or shunt tip (blood cultures positive in 90-98% of endocarditis cases) 1
• Measure anti-streptolysin O, anti-DNAse B, and anti-hyaluronidase antibodies 1
• Rule out other causes: Check ANA, ANCA, anti-GBM antibodies, rheumatoid factor, cryoglobulins 1, 2
• Consider serological testing for fastidious organisms (Candida, Coxiella burnetii, Borrelia, Bartonella) 1

Treatment Strategy

• Treat underlying infection aggressively with appropriate antimicrobials 1
• Avoid cyclophosphamide and rituximab in untreated HBV infection as they accelerate viral replication 1
• For HBV-related GN with HBV DNA >2000 IU/ml: Use nucleos(t)ide analogues per standard HBV guidelines 1

Indications for Kidney Biopsy

Perform kidney biopsy when 1, 2:

• Diagnosis is uncertain or atypical presentation
• C3 remains low beyond 12 weeks (to exclude C3 glomerulopathy)
• Rapidly progressive glomerulonephritis with crescentic changes
• Culture evidence of infection is elusive
• Assessing prognosis or considering immunosuppression

Monitoring Parameters

Short-Term (Weekly to Monthly)

• Kidney function (serum creatinine, eGFR) 2
• Blood pressure control 2
• Urinalysis for hematuria and proteinuria (albumin-creatinine or protein-creatinine ratio) 2
• Electrolytes and acid-base status 2

Long-Term (8-12 Weeks and Beyond)

• C3 complement levels should normalize by 8-12 weeks in uncomplicated PSGN 2
• If C3 remains low beyond 12 weeks: Perform kidney biopsy to exclude C3GN 1, 2
• Monitor for persistent proteinuria, hypertension, and progression to chronic kidney disease 6

Critical Pitfalls to Avoid

• Do not withhold antibiotics in PSGN even if infection has resolved—treatment decreases antigenic load 2
• Do not use immunosuppression routinely in typical PSGN; reserve for severe crescentic disease only 2, 3
• Do not miss alternative diagnoses: Persistently low C3 beyond 12 weeks indicates C3 glomerulopathy, not PSGN 1, 2
• Do not use rituximab or cyclophosphamide in untreated HBV infection-related GN 1
• Do not assume good prognosis in adults: Unlike children, adults with PSGN have higher rates of chronic kidney disease and hypertension 7