Diagnostics

Diagnosis is based on clinical presentation and laboratory results. In some cases, renal biopsy may be indicated to confirm the diagnosis.

• Urinalysis

  • Signs of nephritic sediment, including persistent microhematuria and possibly minor proteinuria

  • Episodic flare-ups of gross hematuria in 50% of patients [7]

  • In rare cases, nephrotic sediment

• Laboratory tests

  • Serum IgA level is elevated in 50% of patients.

  • Complement levels (e.g., C3 level) are generally normal. [12]

• Renal biopsy

  • Usually only indicated if there are signs of severe or progressive disease, including:

    • Urinary protein > 0.5–1 g/24 h

    • ↑ Serum creatinine

    • Hypertension

  • Findings

    • Light microscopy: mesangial proliferation

    • Immunofluorescent microscopy: mesangial IgA deposits

    • Electron microscopy: mesangial immune complex deposits

The renal manifestation of IgA vasculitis is pathologically the same as IgA nephropathy.

Photomicrograph of kidney tissue (PAS stain)

A glomerulus surrounded by numerous tubules is visible in the center of each image. There is a proliferation of mesangial cells (examples marked by yellow circles) with extracellular matrix deposition within the glomeruli. In IgA nephropathy, these changes can range from focal segmental (examples indicated by black arrows) to diffuse (examples indicated by yellow arrow-heads).

This is the characteristic histopathologic appearance of IgA nephropathy.