Usually a clinical diagnosis — rule out other causes
No lab test is diagnostic
Biopsy of affected organ (eg skin or kidney) with predominantly IgA deposition supports diagnosis
CBC (increased WBC and PLT)
CRP/ESR (increased)
Chemistry
PT/PTT (normal)
Urinalysis (hematuria, proteinuria)
Stool guaiac (positive in >50%) — indicates GI vasculitis
Consider abdominal ultrasound — increased risk of intussusception
No lab test is diagnostic
Biopsy of affected organ (eg skin or kidney) with predominantly IgA deposition supports diagnosis
Henoch-Schonlein purpura
Emergent
Serum sickness
Necrotizing Enterocolitis
Kawasaki disease
Volvulus
Hemolytic uremic syndrome
Testicular torsion