From the Guidelines
The workup for acute glomerulonephritis should begin with a comprehensive history and physical examination, followed by laboratory and imaging studies, as recommended by the KDIGO 2021 guideline for the management of glomerular diseases 1. The initial tests should include:
- Urinalysis with microscopy to look for red cell casts, dysmorphic RBCs, and proteinuria
- Complete blood count
- Comprehensive metabolic panel
- Assessment of kidney function with serum creatinine and blood urea nitrogen
- Quantification of proteinuria with a spot urine protein-to-creatinine ratio or 24-hour urine collection Serologic testing should include:
- Complement levels (C3, C4)
- Antinuclear antibody (ANA)
- Anti-neutrophil cytoplasmic antibodies (ANCA)
- Anti-glomerular basement membrane antibodies
- Hepatitis B and C serologies
- HIV testing
- Antistreptolysin O titers if post-streptococcal disease is suspected Renal ultrasound should be performed to assess kidney size and structure. A kidney biopsy is often necessary for definitive diagnosis, especially in cases with rapidly declining renal function, significant proteinuria, or unclear etiology, as it helps determine the specific type of glomerulonephritis and guides treatment decisions 1. Management depends on the underlying cause but may include antibiotics for infection-related cases, immunosuppressive medications like corticosteroids, cyclophosphamide, or rituximab for immune-mediated forms, and supportive care including blood pressure control and fluid management, with the goal of preventing disease progression and reducing proteinuria as a surrogate endpoint 1.
From the Research
Diagnosis of Acute Glomerulonephritis
The diagnosis of acute glomerulonephritis (AGN) typically involves a combination of clinical presentation, laboratory tests, and renal biopsy. Key features of AGN include:
- Abrupt onset of hematuria, facial edema, hypertension, and impairment of renal function 2
- Presence of immune complexes, such as those found in post-streptococcal glomerulonephritis (PSAGN) 2
- Systemic symptoms, such as fever, rash, and arthralgias, may be present in certain types of glomerulonephritis, such as those associated with systemic vasculitis or collagen vascular diseases 3, 2
Laboratory Tests
Laboratory tests used to diagnose AGN include:
- Urinalysis to detect hematuria and proteinuria 4, 3, 2
- Serum creatinine and electrolyte levels to assess renal function 4, 3
- Antineutrophil cytoplasmic antibodies (ANCAs), anti-double-stranded DNA antibodies, anti-glomerular basement membrane (GBM) antibodies, and other serologic tests to identify specific types of glomerulonephritis 3
- Complement levels and other immunological tests to support the diagnosis 3
Renal Biopsy
Renal biopsy is considered the gold standard for diagnosing glomerulonephritis, as it allows for direct visualization of the glomerular injury and identification of specific histopathological patterns 4, 3, 2, 5. However, biopsy may not always be feasible, especially in critically ill patients.
Classification of Glomerulonephritis
Glomerulonephritis can be classified into several types, including:
- Immune-complex glomerulonephritis (e.g., infection-related glomerulonephritis, IgA nephropathy, lupus nephritis) 5
- Anti-neutrophil cytoplasmic antibodies (ANCA)-associated glomerulonephritis 3, 5
- Anti-glomerular basement membrane glomerulonephritis 3, 5
- C3 glomerulopathy 5
- Monoclonal immunoglobulin-associated glomerulonephritis 5
Treatment Approach
The treatment approach for AGN depends on the underlying cause and severity of the disease. General measures include: