IgA Vasculitis - Henoch Schönlein Purpura


Indications for Testing

  • Palpable purpura in patient ≤20 years with other systemic symptoms

Criteria for Diagnosis

  • Diagnosis is primarily clinical
  • American College of Rheumatology Criteria (1990)
    • 2 of 4 must be present (sensitivity 87.1%, specificity 82.7%)
      • Palpable purpura
      • Age – ≤20 years
      • Bowel angina – defined as abdominal pain
      • Vascular wall granulocytes on biopsy seen in the arterioles and venules
  • EULAR criteria (2010)
    • Palpable purpura, not thrombocytopenic/petechiae (mandatory) and ≥one of the following
      • Diffuse abdominal pain
      • Histopathology – typical LCV with predominant IgA deposits or proliferative glomerulonephritis with predominant IgA deposits
      • Arthritis or arthralgias
      • Renal involvement
      • Proteinuria

        0.3 g/24 h 


        >30 mmol/mg of urine albumin to creatinine ratio on a spot morning sample


        Hematuria – red blood cell casts

        >5 red cells per high power field 


        ≥2+ on dipstick 


        Red blood cell casts in the urinary sediment

Laboratory Testing

  • Nonspecific testing – helpful in excluding other diagnoses or identifying organ dysfunction
    • CBC – normal platelet count rules out idiopathic thrombocytopenic purpura, thrombotic microangiopathies
    • Urinalysis – hematuria common
    • C-reactive protein (CRP)
    • BUN/creatinine – may be elevated from renal involvement or dehydration
    • Serum IgA – elevated in many patients


  • Granulocytes in small vessel (arterioles and venule walls) with IgA and C3 immune deposition
  • Glomerulonephritis of IgA vasculitis may be indistinguishable from IgA nephropathy or other glomerulonephritis

Differential Diagnosis 

Clinical Background

IgA vasculitis (formerly Henoch Schönlein purpura) is classified as a small-vessel vasculitis that predominantly affects the skin, gastrointestinal tract and can be associated with arthritis (Chapel Hill 2012). IgA vasculitis is the most common vasculitis of childhood.


  • Incidence – 13-14/100,000 in U.S.
  • Age – typically diagnosed in children 3-10 years
    • Majority are diagnosed in children >5 years
  • Sex – M>F, 2:1


  • Systemic necrotizing small-vessel vasculitis characterized by tissue deposition of IgA containing immune complexes, most commonly in skin and kidney

Clinical Presentation

  • Typically a benign, self-limited disorder
    • A few cases cause chronic symptoms
    • Very small number of cases progress to end-stage renal failure
  • Classic clinical tetrad of symptoms
    • Rash – palpable purpura
      • Often concentrated on extensor surfaces of lower extremities
    • Polyarthralgia – most commonly in knees and ankles
      • Often edema also present
    • Abdominal pain – associated with nausea, emesis, diarrhea
      • Colicky quality
    • Renal disease – mild glomerulonephritis with microscopic hematuria, red cell casts, proteinuria
  • Other organ involvement
    • Neurologic (rare)
    • Pulmonary (rare)
      • Diffuse alveolar hemorrhage
    • May present as single organ vasculitis
  • Disease onset mostly occurs in the winter months, suggesting an infectious trigger
    • Frequently preceded by upper respiratory tract infection – ~50% of cases
    • Also associated with gastrointestinal infection
  • May be associated with other diseases or these diseases may be causal
    • Liver disease
    • IBD
    • Ankylosing spondylitis

Indications for Laboratory Testing

  • Tests generally appear in the order most useful for common clinical situations
  • Click on number for test-specific information in the ARUP Laboratory Test Directory
Test Name and Number Recommended Use Limitations Follow Up
CBC with Platelet Count and Automated Differential 0040003
Method: Automated Cell Count/Differential

Aid in evaluation for infectious process

C-Reactive Protein 0050180
Method: Quantitative Immunoturbidimetry

Preferred test to evaluate for suspected vasculitis

Urinalysis, Complete 0020350
Method: Reflectance Spectrophotometry/Microscopy

Screen for hematuria, proteinuria, and RBC casts

Urea Nitrogen, Serum or Plasma 0020023
Method: Quantitative Spectrophotometry

Screening test to evaluate kidney function

Creatinine, Serum or Plasma 0020025
Method: Quantitative Enzymatic

Screening test to evaluate kidney function

Additional Tests Available
Click the plus sign to expand the table of additional tests.
Test Name and NumberComments
Sedimentation Rate, Westergren (ESR) 0040325
Method: Visual Identification

Evaluation for suspected vasculitis

Immunoglobulin A 0050340
Method: Quantitative Nephelometry

Screen for elevation