Pediatric Henoch-Schönlein Purpura Nephritis: Diagnosis and Monitoring Strategies

Henoch-Schönlein purpura (HSP) nephritis is a form of immune-mediated kidney injury that commonly affects children following an episode of systemic vasculitis. It typically develops within six months after the onset of skin purpura, a hallmark symptom of HSP. Early detection is crucial to prevent long-term renal complications, and healthcare providers rely on a combination of clinical signs and diagnostic evaluations to identify kidney involvement.

Key Indicators of HSP-Related Kidney Involvement

Kidney damage in pediatric HSP patients may manifest through several clinical and laboratory findings. The presence of any one of the following during the first six months post-purpura warrants further investigation:

Abnormal urinalysis – including microscopic or gross hematuria (blood in urine), proteinuria (excess protein), or elevated microalbumin levels.
Renal imaging abnormalities – such as changes in renal parenchyma observed via ultrasound, which may indicate inflammation or structural damage.
Impaired kidney function – evidenced by elevated serum creatinine, reduced glomerular filtration rate (GFR), or signs of acute or chronic renal insufficiency.

Primary Diagnostic Tools for HSP Nephritis

Urinalysis remains the cornerstone of initial screening for HSP-related kidney disease. A routine dipstick test can quickly detect hematuria and proteinuria, while microscopic examination provides more detailed insights into red blood cell morphology and cellular casts—key indicators of glomerular injury.

Advanced Urinary Assessments

In cases where initial results are inconclusive or show persistent abnormalities, physicians often recommend:

Urine microscopy with phase contrast to analyze dysmorphic red blood cells, suggesting glomerular origin.
24-hour urine protein quantification to assess the severity of protein loss, which helps classify the condition from mild to nephrotic-range proteinuria.

When Is a Kidney Biopsy Necessary?

If a child presents with significant proteinuria, especially approaching nephrotic levels, or shows signs of rapidly declining kidney function, a renal biopsy may be indicated. This invasive but highly informative procedure allows pathologists to determine the histological class of HSP nephritis according to standardized grading systems (e.g., ISKDC classification). The biopsy results guide treatment decisions, particularly regarding the use of immunosuppressive therapy.

Recommended Monitoring Schedule After HSP Onset

Given the high incidence of renal involvement—up to 20–50% of pediatric HSP cases—systematic follow-up is essential. Experts suggest the following surveillance protocol based on timing after rash resolution:

First month: Weekly urinalysis to catch early signs of glomerular damage.
Months 2–3: Testing every two weeks, as subclinical progression may still occur.
Months 4–6: Monthly checks to ensure no late-onset renal manifestations develop.

This tiered monitoring approach maximizes early intervention potential while minimizing unnecessary testing in low-risk individuals.

Next Steps After Abnormal Test Results

If urinalysis reveals persistent hematuria, proteinuria, or both, referral to a pediatric nephrologist is strongly advised. Specialized evaluation may include additional blood tests (e.g., complement levels, ANA), repeat imaging, and discussion of biopsy eligibility. Timely specialist input improves outcomes by enabling personalized management plans tailored to disease severity.

Early diagnosis and structured follow-up significantly reduce the risk of chronic kidney disease in children with HSP. Parents and caregivers should remain vigilant for symptoms like frothy urine, facial swelling, or decreased urine output, all of which warrant immediate medical attention.