Diagnostics

IgAV is a clinical diagnosis, laboratory tests are not essential to IgAV diagnosis. However, they may be useful for excluding differential diagnoses in patients exhibiting only one or two of the IgAV tetrad of symptoms, as is often the case in the first few days. Laboratory tests are also useful for monitoring the extent of renal involvement, which helps determine the prognosis. Definitive diagnosis in uncertain cases is made via biopsy.

• Indications: useful in patients with an incomplete or unusual presentation

• Complete blood cell count with differential

  • ↑ Platelet count

  • ↑ White blood cell count

  • ↓ Hemoglobin

• Coagulation profile: usually normal

• Serum antibodies and complement

  • ↑ IgA in serum

  • Evidence of circulating IgA immune complexes

  • ↓ Complement

  • In case of preceding streptococcal infection: antistreptolysin O (ASO) titers

• Serum chemistry

  • ↑ Creatinine and/or BUN

  • Electrolyte imbalances

• Urinalysis to assess possible renal disease

  • Hematuria, often with RBC casts

  • Possibly proteinuria

• Inflammatory markers

  • ↑ ESR

  • ↑ CRP

• In case of GI involvement: positive stool guaiac

The platelet count in IgAV is normal or elevated, as opposed to other causes of purpura.

• Indication: performed in patients with marked abdominal symptoms or suspected complications

• Modalities: abdominal ultrasound/CT

Indications: reserved for patients with unusual skin presentations or severe renal involvement (e.g., persistent nephritic syndrome)

• Skin: leukocytoclastic vasculitis with IgA and C3 immune complex deposition (hallmark) in small vessels of the superficial dermis

• Kidney

  • Mesangial IgA deposition

  • C3 complement and fibrin

  • Crescent formation in more severe cases