IgA vasculitis

Last updated 28 Mar 2026

IgA Vasculitis

IgA vasculitis (IgAV), formerly known as Henoch-Schönlein purpura (HSP), is an immune complex small-vessel vasculitis characterised by IgA1-dominant immune deposits in vessel walls. It is the most common systemic vasculitis in children but also occurs in adults, in whom it tends to be more severe with higher rates of persistent nephritis. The classic clinical tetrad comprises palpable purpura (non-thrombocytopenic), arthritis or arthralgia, abdominal pain, and renal involvement. IgAV is often self-limiting in children but may cause chronic kidney disease, particularly when nephritis is severe.

Australian Epidemiology

IgAV is the most common vasculitis in children in Australia, with an incidence of approximately 10–20 per 100,000 children per year. Peak age is 4–6 years; 90% of cases occur in children under 10 years. A seasonal pattern is observed, with higher incidence in autumn and winter, consistent with preceding upper respiratory tract infections. Adults with IgAV have a higher incidence of renal involvement (approximately 50–60%) and more severe nephritis compared to children. IgA nephropathy (Berger disease) is closely related to IgAV nephritis and represents isolated renal IgA disease.

Pathophysiology

IgA1 Immune Complex Deposition

IgAV is driven by aberrantly glycosylated IgA1 (galactose-deficient IgA1, Gd-IgA1) that forms immune complexes with IgG and IgA anti-glycan antibodies. These circulating immune complexes deposit in the walls of small vessels (capillaries, venules, arterioles) throughout the body — skin, gut, joints, and kidney. Complement activation via the lectin and alternative pathways drives neutrophil recruitment and endothelial damage, resulting in leukocytoclastic vasculitis.

Renal Involvement

IgA immune complex deposition in the mesangium causes mesangial proliferative glomerulonephritis, identical to IgA nephropathy. More severe forms include crescentic glomerulonephritis. Mediators including platelet-derived growth factor (PDGF) and TGF-β drive mesangial expansion, interstitial fibrosis, and progressive CKD. Adult IgAV nephritis is associated with 30–50% risk of chronic kidney disease at 15–20 years.

Triggers

IgAV commonly follows upper respiratory tract infections (Group A streptococcus, Staphylococcus aureus, adenovirus, Epstein-Barr virus). Other triggers include vaccinations, medications (ACE inhibitors, antibiotics), and malignancy (particularly in adults — screen for lymphoma and solid organ tumours in adult-onset IgAV).

Clinical Presentation

Classic Tetrad

Palpable purpura (100%): Raised, non-blanching purpuric lesions predominantly over buttocks and lower limbs; may be urticarial initially; non-thrombocytopenic — platelets are normal
Arthritis/Arthralgia (60–80%): Oligoarticular, predominantly lower limb (knees, ankles); swelling and pain without erythema; self-limiting, non-destructive
Abdominal pain (50–70%): Colicky, diffuse; may be severe; GI complications include intussusception (2–3%), bowel haemorrhage, intestinal perforation; melaena or bloody stool
Renal involvement (20–60%): Haematuria (microscopic or macroscopic), proteinuria, hypertension; RPGN rare but may occur; renal prognosis determines long-term outcome

Adults vs Children

Adults with IgAV tend to have more severe and persistent disease. Renal involvement is more common (50–60% vs 20–40% in children) and more severe. Skin involvement may be more extensive. Abdominal complications are less common. Malignancy as an underlying trigger must be excluded in all adults with IgAV.

Investigations

Essential
Urinalysis and Urine Microscopy
Haematuria (red cells ± red cell casts) and proteinuria indicate nephritis. Must be checked at presentation and at each follow-up visit. Proteinuria >1 g/day warrants nephrology referral and biopsy consideration.
Essential
Full Blood Count and Coagulation
Thrombocytopenia excludes IgAV (purpura in IgAV is non-thrombocytopenic — platelet count is normal or elevated). Coagulopathy excluded. Leukocytosis in active inflammation.
Essential
Serum IgA Level
Elevated IgA in 50–60% of IgAV cases. Supports diagnosis but not required — normal IgA does not exclude IgAV. Elevated IgA also seen in IgA nephropathy, liver disease, and coeliac disease.
Essential
Renal Function (eGFR, Creatinine)
Baseline and serial monitoring. Rising creatinine with haematuria is an emergency — urgent nephrology referral. Most children maintain normal renal function; adults at higher risk of progression.
Available
Throat Swab and ASO Titre
Identify preceding streptococcal infection. Positive ASO titre or throat culture supports streptococcal trigger — treat with phenoxymethylpenicillin if not already treated.
Referral
Skin Biopsy (Direct Immunofluorescence)
IgA deposits in vessel walls on DIF are pathognomonic of IgAV. Indicated when diagnosis uncertain or atypical presentation. Also useful in adults to exclude other diagnoses.
Referral
Renal Biopsy
Indicated for: proteinuria >1 g/day, nephrotic syndrome, renal impairment, or hypertension. IgA mesangial deposits on immunofluorescence are diagnostic. Oxford classification grades severity.

Severity Assessment

MILD

Skin and Joints Only

Purpura + arthralgia, no abdominal or renal involvement

Supportive care; analgesia (paracetamol); monitor urine 6–12 months

MODERATE

GI or Mild Nephritis

Abdominal pain, microscopic haematuria, proteinuria <1 g/day, normal renal function

Corticosteroids for severe GI pain; nephrology monitoring; ACE inhibitor if proteinuria >0.5 g/day

SEVERE

Significant Nephritis

Proteinuria >1 g/day, nephrotic syndrome, rising creatinine, RPGN, bowel complication

Corticosteroids ± immunosuppression (azathioprine/MMF); urgent nephrology; surgical review if bowel complication

Treatment Strategy

Supportive Care (Mild Disease)

Most children with IgAV have self-limiting disease requiring only supportive care. Rest during active purpura (reduces new lesion formation with gravity). Paracetamol for joint pain and fever. NSAIDs used cautiously — may worsen renal and GI outcomes. Adequate hydration. Monitor urinalysis at each visit and for 6–12 months after resolution to detect late-onset nephritis.

Corticosteroids

Prednisolone (1 mg/kg/day, max 40–60 mg/day) for severe abdominal pain causing functional impairment, scrotal involvement, or significant arthritis not responding to analgesia. Corticosteroids do NOT prevent nephritis development but may reduce abdominal complications. Taper over 2–4 weeks once symptoms controlled. Prednisolone is the first-line treatment for moderate-severe IgAV nephritis.

Nephritis Management

ACE inhibitor (ramipril or enalapril) or ARB for proteinuria >0.5 g/day — reduces proteinuria and slows CKD progression. For moderate-severe nephritis (proteinuria >1 g/day, nephrotic syndrome, or renal impairment): prednisolone 1 mg/kg/day + azathioprine or mycophenolate mofetil (MMF). For crescentic nephritis with RPGN: IV methylprednisolone pulses + cyclophosphamide or rituximab, in consultation with nephrology.

Directed Therapy

💊

Prednisolone

Panafcort® · Corticosteroid

Adult Dose0.5–1 mg/kg/day (max 60 mg/day)

Paediatric1–2 mg/kg/day (max 40–60 mg/day)

RouteOral

Duration2–4 weeks (acute); longer with nephritis

Renal Adj.No adjustment required

PBS Status✓ PBS General Benefit

💊

Ramipril

Tritace®, Ramace® · ACE Inhibitor · Nephroprotection

Adult Dose2.5–10 mg once daily (titrate to max tolerated)

Paediatric0.05–0.1 mg/kg/day (specialist dosing)

RouteOral

FrequencyOnce daily

DurationLong-term if proteinuria persists

Renal Adj.Start low if eGFR <45; monitor creatinine and potassium closely

PBS Status✓ PBS General Benefit

💊

Mycophenolate Mofetil

CellCept® · Antimetabolite · Nephritis

Adult Dose1–1.5 g twice daily (2–3 g/day total)

Paediatric600 mg/m² twice daily (max 2 g/day)

RouteOral

FrequencyTwice daily

Duration1–2 years; review with nephrology

Renal Adj.No dose adjustment for GFR >25

PBS StatusPBS Authority Required

Acute Management

Intussusception

Intussusception is the most common severe GI complication of IgAV in children (2–3%). Presents with severe colicky abdominal pain, vomiting, and bloody stools. Urgent abdominal ultrasound for diagnosis — target sign on cross-section. Unlike idiopathic intussusception, IgAV intussusception is usually ileo-ileal (not ileocaecal), making air-enema reduction less effective. Surgical intervention is often required. High-dose IV corticosteroids may reduce recurrence risk after reduction.

Severe Abdominal Pain Without Intussusception

Prednisolone 1–2 mg/kg/day (max 60 mg) provides rapid relief of severe GI pain from IgAV. IV methylprednisolone 10 mg/kg/day for 3 days for hospitalised patients unable to tolerate oral medications. IV fluids for dehydration. Bowel rest (NBM) during severe pain episodes. IV opioid analgesia (morphine) for breakthrough pain.

Scrotal Involvement

Scrotal oedema and pain from IgAV vasculitis of the scrotal skin and tunica vaginalis occurs in 10–15% of boys. Must be distinguished from testicular torsion — urgent Doppler ultrasound. If blood flow preserved and torsion excluded: prednisolone and monitoring. Surgical exploration if torsion cannot be excluded.

Monitoring and Follow-up

Renal Surveillance

Urinalysis (dipstick for blood and protein) and blood pressure at every clinical review. Nephritis can develop or worsen up to 6 months after the initial presentation — all patients require urine monitoring for at least 6 months from symptom onset, even after apparent resolution. Protein/creatinine ratio for proteinuria quantification if dipstick positive. 24-hour urine protein if >1+ proteinuria.

Monitoring Schedule

Acute Phase

Urinalysis, BP, renal function at presentation and every 1–2 weeks while active. FBC if thrombocytopenia or bleeding concern.

Months 1–3

Monthly urinalysis and BP. Renal function if haematuria or proteinuria. Nephrology referral if proteinuria >1 g/day or renal impairment.

Months 3–6

Urinalysis every 4–6 weeks. BP at each visit. Discharge from follow-up if urinalysis consistently normal for 3 consecutive months.

Long-term (Nephritis)

6-monthly urinalysis and BP for at least 5 years in patients with nephritis. Annual eGFR. Nephrology specialist follow-up for moderate-severe nephritis.

Special Populations

👶 Infants and Young Children

Atypical PresentationInfants under 2 years may have oedema (scalp, periorbital, scrotum, dorsum of hands/feet) and irritability as prominent features before purpura appears. Maintain suspicion for IgAV even without classic purpura initially.

Generally MilderYounger children tend to have milder nephritis and better renal prognosis than older children and adults. Supportive care is often sufficient. Reassurance to parents is important.

👴 Adult IgAV

More Severe NephritisAdults have significantly higher rates of severe nephritis and CKD. Renal biopsy is recommended for adults with any degree of proteinuria. Long-term nephrological follow-up is mandatory.

Malignancy ScreeningAll adult-onset IgAV should have age-appropriate cancer screening (occult blood, CT chest/abdomen/pelvis, PSA in men, mammogram in women) as IgAV may be a paraneoplastic phenomenon.

RecurrenceIgAV recurs in 30–40% of adults (vs 10% in children). Recurrences may be more severe. Identify and manage modifiable triggers. Long-term renal surveillance essential.

Aboriginal and Torres Strait Islander Health Considerations

Aboriginal and Torres Strait Islander Health

IgA vasculitis occurs in Aboriginal and Torres Strait Islander children and adults. The high prevalence of Group A streptococcal (GAS) infections — including streptococcal skin infections (impetigo) and pharyngitis — in Aboriginal and Torres Strait Islander communities may act as triggers for IgAV. Additionally, the high background prevalence of IgA nephropathy and post-streptococcal glomerulonephritis in these communities creates potential diagnostic complexity when haematuria and proteinuria are identified.

Streptococcal Skin Infection

Group A streptococcal impetigo (school sores) is highly prevalent in Aboriginal and Torres Strait Islander children. Prompt treatment with benzylpenicillin or oral phenoxymethylpenicillin is essential. Treat household contacts as well. GAS skin infection as an IgAV trigger should be considered in any child presenting with purpura following skin infection.

Renal Surveillance Challenges

Urinalysis follow-up for 6–12 months after IgAV may be difficult in remote communities. Establish shared care plans with remote health services, including clear instructions for urinalysis and blood pressure monitoring. Community health nurses play a key role in follow-up.

Distinguishing Diagnoses

Post-streptococcal glomerulonephritis, IgA nephropathy, and IgAV nephritis can all present with haematuria and proteinuria following GAS infection in Aboriginal and Torres Strait Islander patients. Low complement (C3) supports post-streptococcal GN; skin biopsy and renal biopsy may be required to distinguish these conditions definitively.

Antimicrobial Stewardship

Treating the Trigger

IgAV is an immune-mediated post-infectious condition. Antibiotic stewardship principles in IgAV:

Treat confirmed Group A streptococcal pharyngitis or skin infection with appropriate antibiotics (phenoxymethylpenicillin 500 mg BD for 10 days for pharyngitis; benzylpenicillin IM for impetigo in high-risk settings) to eliminate the infectious trigger
Do not use antibiotics prophylactically to prevent IgAV recurrence — no evidence of benefit
Do not use antibiotics as anti-inflammatory therapy for IgAV rash, arthritis, or abdominal pain — corticosteroids are the appropriate treatment
Throat swab culture should guide antibiotic choice — do not empirically treat without microbiological confirmation where possible
For patients on immunosuppression (corticosteroids + azathioprine/MMF): PJP prophylaxis with trimethoprim-sulfamethoxazole should be considered for those on prolonged combined therapy

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