IgA vasculitis (IgAV), previously referred to as Henoch-Schonlein purpura (HSP), is an acute immune complex-mediated small vessel vasculitis that most commonly occurs in children. Onset is often preceded by an upper respiratory tract or gastrointestinal infection; IgAV in adults may be idiopathic. Affected individuals typically develop palpable purpura, arthritis and/or arthralgia, and abdominal pain. Renal involvement (i.e., IgAV nephritis) is more common and usually more severe in adults than in children, typically manifesting with hematuria. While IgAV is a clinical diagnosis, laboratory studies are used to identify organ involvement and exclude differential diagnoses, and skin biopsy can confirm the diagnosis in patients with atypical presentations. IgAV is usually self-limited; treatment is generally supportive. Systemic glucocorticoids may be required depending on severity of manifestations (e.g., in IgAV nephritis, orchitis). IgAV has an excellent prognosis in children, usually resolving within one month when not complicated by IgAV nephritis. Adults often manifest with more severe features and have lower remission rates. All patients require follow-up assessments to rule out the development of chronic renal disease.
The exact pathogenesis is unknown and assumed to be multifactorial. Factors that likely play a role include:
- Preceding infection
- IgA nephropathy
- Drugs (e.g., ACE inhibitors, clarithromycin) and vaccines
- Genetic predisposition
- Solid-organ malignancies (in adults) 
An upper respiratory tract infection often precedes symptom onset by 1–3 weeks. 
- Constitutional symptoms: low-grade fever, malaise, fatigue
Skin (∼ 100% of cases) 
- Symmetrically distributed erythematous papules or urticarial lesions that coalesce into palpable purpura
- Bullae, pustules, and necrotic or hemorrhagic purpura (more common in adults) 
- Most commonly in the lower extremities, buttocks, and other areas of pressure or constraint (e.g., from clothing)
- Joints (∼ 75% of cases) 
- Gastrointestinal tract (∼ 60% of cases) 
Kidneys: IgAV nephritis (20–50% of children; 50–80% of adults) ; 
- See also “IgA nephropathy.”
- Other organs (rare)
IgAV is characterized by PAPAH: purpura, abdominal pain, arthritis/arthralgia, and hematuria.
IgAV is an important differential diagnosis to consider in children with a limp.
Pediatric and adult patients
- Make a clinical diagnosis of IgAV based on typical clinical features.
- Check history for recent infections, medications, and vaccination as potential precipitating factors.
- Obtain laboratory studies to identify organ involvement and exclude alternative diagnoses.
- If abdominal pain is present, obtain imaging studies to investigate for GI bleeding and intussusception.
- If the diagnosis remains unclear, refer to a specialist for confirmatory biopsy. 
- Adult-specific considerations 
Laboratory studies 
Baseline laboratory studies
Obtain the following studies in all patients to assess for renal and GI involvement:
- BMP: ↑ creatinine and/or ↑ BUN suggest IgAV nephritis
- Coagulation panel: typically normal
- Urine: may be normal, abnormal values suggest IgAV nephritis
- Stool blood test: positive if there is GI bleeding
Additional laboratory studies
The following studies may support the diagnosis of IgAV but are not required in the diagnostic workup.
- LFTs: ↓ albumin due to intestinal protein loss
- ↑ ESR, CRP
- If preceding streptococcal infection:
- ↑ IgA in serum: in ∼ 60% of cases; not specific for IgAV 
Imaging studies should be obtained according to the patient's symptoms and/or suspected complications.
- Abdominal ultrasound: indicated in patients with abdominal pain to evaluate for intussusception
- CT abdomen and pelvis: if ultrasound is inconclusive or if further evaluation is required
- Duplex ultrasound of the scrotum: if there is testicular pain to evaluate for orchitis or torsion
- Additional studies: based on clinical presentation (e.g., MRI brain to evaluate for cerebral vasculitis)
EULAR/PRINTO/PReS classification criteria 
Classification criteria can be used to distinguish IgAV from other types of vasculitides, but should not be used as diagnostic criteria for IgAV. 
- Purpura or petechiae (predominantly in the lower limbs)
- Plus ≥ 1 of the following:
|Differential diagnosis of IgAV based on clinical features|
|Clinical feature of IgAV||Differential diagnosis||Distinguishing features of the differential diagnosis|
|Renal disease|| |
The differential diagnoses listed here are not exhaustive.
Decisions about pharmacotherapy are based on symptom severity and should be guided by a specialist.
All patients: Provide supportive care.
- Ensure adequate hydration: oral rehydration therapy and IV fluid therapy as needed
- Provide NSAIDs and/or acetaminophen for pain (see “Oral analgesics” for dosages).
- Treat skin lesions with leg elevation, compression stockings, and/or wound care of ulcerative lesions. 
- Discontinue drugs suspected of inducing IgAV. 
- Patients with severe vasculitis and/or IgAV nephritis
Most cases of IgAV are self-limited and only require supportive care.
Systemic glucocorticoids 
- Indications 
Specialist consultation 
Consider early consultation as follows:
- Nephrology for IgAV nephritis; treatment options include:
- Systemic glucocorticoids (first-line treatment) 
- Other immunosuppressive agents (second-line treatment), e.g., azathioprine, mycophenolate mofetil, IV cyclophosphamide 
- ACEI, ARB , e.g.,
- Gastroenterology: if there is blood in stool and/or severe or progressive abdominal pain
- Rheumatology: for recurrent or refractory IgAV
- All patients require scheduled outpatient follow-up to monitor for delayed renal impairment (See “Follow-up of IgAV”)
- Consider hospital admission for patients with severe IgAV if any of the following are present:
- Renal 
We list the most important complications. The selection is not exhaustive.
Patients with IgAV require follow-up due to an increased risk of chronic kidney disease. 
- Patients with proteinuria or hypertension: every 2 weeks for 1 month, then every 1–2 months for 6–12 months, then every 3–6 months
- Patients without proteinuria or hypertension: every 2 weeks for 1 month, then every 2–3 months for 6–12 months, then annually
- Repeat if the patient develops AKI or a nonrenal flare (e.g., cutaneous lesions, GI symptoms)
- Refer to nephrology if there is:
IgAV nephritis typically develops within 6 months of IgAV symptom onset.