Diagnosing IgA Vasculitis with Nephritis: Symptoms, Testing, and Pathological Insights

Identifying IgA vasculitis-associated nephritis—formerly known as Henoch-Schönlein purpura (HSP) nephritis—requires a comprehensive evaluation combining clinical symptoms, laboratory findings, and histopathological evidence from kidney tissue. This condition is an immune-mediated small vessel vasculitis that primarily affects children but can also occur in adults, often following an upper respiratory infection or other environmental triggers.

Key Clinical Criteria for Diagnosis

Healthcare providers typically rely on a triad of diagnostic indicators to confirm IgA vasculitis with renal involvement. Meeting these three major criteria increases diagnostic accuracy and helps differentiate it from other forms of glomerulonephritis.

1. Characteristic Skin Manifestations

One of the hallmark signs is palpable purpura—a type of non-blanching rash caused by bleeding under the skin. These purple or reddish spots usually appear symmetrically on the lower extremities and buttocks, although they may spread to other areas. Unlike simple bruising, this rash does not fade when pressed and often occurs without significant trauma. Additional extrarenal symptoms may include joint pain (arthralgia), abdominal discomfort, and gastrointestinal bleeding.

2. Evidence of Kidney Involvement

Renal complications are common in moderate to severe cases. Patients may present with hematuria (blood in urine), proteinuria (excess protein in urine), hypertension, peripheral edema (swelling in legs or face), or even reduced kidney function. In some instances, these urinary abnormalities progress to nephrotic syndrome or acute kidney injury, necessitating prompt medical attention.

3. Definitive Histopathological Findings

The gold standard for diagnosis is a kidney biopsy showing characteristic immunoglobulin A (IgA) deposits in the mesangial region of the glomeruli. Microscopic examination typically reveals mesangial proliferation and immune complex deposition, confirmed through immunofluorescence staining. The presence of IgA-dominant or co-dominant immune complexes strongly supports the diagnosis of IgA-mediated vasculitis.

Diagnostic Tools and Laboratory Workup

To support clinical suspicion, physicians use a combination of blood and urine tests along with imaging and invasive procedures when necessary.

Blood tests may show elevated inflammatory markers, mild anemia, or abnormal kidney function values such as increased serum creatinine and reduced estimated glomerular filtration rate (eGFR). Urinalysis is crucial—it can detect microscopic or gross hematuria, proteinuria, and cellular casts, all indicating glomerular damage.

In ambiguous cases, a renal biopsy becomes essential. It provides detailed histological insights into the extent of inflammation, scarring, and immune deposit patterns. This information guides treatment decisions and helps predict long-term outcomes, including the risk of chronic kidney disease.

Why Early Detection Matters

Timely diagnosis allows for early intervention, which can significantly improve prognosis. While many pediatric cases resolve spontaneously, adults and those with severe histological changes may require immunosuppressive therapy or corticosteroids to prevent progressive kidney damage.

Given its variable presentation, awareness among clinicians and patients about the link between systemic symptoms and kidney health is vital. Monitoring individuals with recent rashes or infections for urinary abnormalities can lead to earlier referrals and better management strategies.