From the Guidelines
IGA vasculitis and post-streptococcal glomerulonephritis (PSGN) are distinct kidney conditions with different causes, presentations, and treatments, as outlined in the KDIGO 2021 clinical practice guideline for the management of glomerular diseases 1.
Key Differences
- IGA vasculitis is an immune-mediated small vessel vasculitis characterized by IgA immune complex deposition, typically presenting with palpable purpura on the lower extremities, abdominal pain, arthralgia, and renal involvement.
- PSGN is a specific immune complex-mediated glomerulonephritis that develops 1-2 weeks after a streptococcal infection (usually throat or skin), presenting with hematuria, proteinuria, edema, and hypertension.
Laboratory Findings
- IgA vasculitis shows elevated IgA levels and IgA deposits on kidney biopsy.
- PSGN shows low C3 complement levels that normalize within 8 weeks, anti-streptolysin O (ASO) or anti-DNase B antibodies, and "starry sky" pattern on immunofluorescence with C3 and IgG deposits.
Treatment and Prognosis
- Treatment differs: IgA vasculitis may require corticosteroids for severe cases, while PSGN typically resolves spontaneously with supportive care and antibiotics to eradicate streptococcal infection.
- Prognosis also varies, with PSGN generally having excellent outcomes in children, while IgA vasculitis has a more variable course with potential for chronic kidney disease, as noted in the KDIGO guideline update 2.
Clinical Management
- The KDIGO 2021 guideline provides evidence-based recommendations for the management of glomerular diseases, including IgA vasculitis and PSGN, with a focus on diagnosis, prognosis, treatment, and special situations 3.
- The guideline emphasizes the importance of distinguishing between different types of glomerulonephritis, such as IgA vasculitis and PSGN, to ensure appropriate treatment and management, as highlighted in the commentary on the 2012 KDIGO guideline 4.
- The guideline also notes that post-streptococcal GN, including PSGN, should be treated with penicillin (or erythromycin, if penicillin-allergic) to decrease the antigenic load, and that corticosteroids may be suggested for severe crescentic GN based on anecdotal evidence only 5.
From the Research
Differences between IgA Vasculitis and Post-Streptococcal Glomerulonephritis
- IgA vasculitis is an inflammation of small vessels caused by perivascular deposition of IgA and activation of neutrophils, whereas post-streptococcal glomerulonephritis (PSGN) is an immune-complex mediated inflammation that occurs after an infection with nephritogenic strains of group A beta-hemolytic streptococci 6, 7.
- The clinical features of IgA vasculitis include palpable purpura, arthralgia, gastrointestinal bleeding, and glomerulonephritis with mesangial IgA deposits, whereas PSGN is characterized by nephritic syndrome manifestation, including hematuria, proteinuria, and renal impairment 6, 7.
- The pathophysiology of IgA vasculitis involves the deposition of immune complexes containing galactose-deficient IgA1, which induces neutrophilic inflammation around cutaneous vessels and mesangial proliferation and inflammation in the glomerulus 6.
- In contrast, PSGN is caused by the formation of an immune complex of antigen-antibody and complement system, which deposits in the glomeruli and leads to inflammation 7.
- The treatment of IgA vasculitis is symptomatic, with corticosteroids and immunosuppressive drugs used in severe cases, whereas the management of PSGN is also symptomatic, with antibiotic therapy used to prevent the development of the complication 6, 7.
Overlapping Features
- Both IgA vasculitis and PSGN can present with glomerulonephritis and renal impairment 6, 7.
- There have been cases reported of PSGN superimposed on IgA nephropathy, with histological findings showing both IgA deposits and immune complex deposition characteristic of PSGN 8.
- Additionally, there have been cases of streptococcal infection-related IgA vasculitis with associated glomerulonephritis and leukocytoclastic cutaneous vasculitis, suggesting a possible link between the two conditions 9.