How to Diagnose Henoch-Schönlein Purpura Nephritis in Children

When children with Henoch-Schönlein purpura (HSP) develop kidney involvement, the condition is referred to as HSP nephritis or IgA vasculitis nephritis. Diagnosis of this complication can be confirmed within six months of the onset of HSP if any one of the following clinical indicators is present.

Key Diagnostic Criteria for HSP Nephritis

1. Abnormal Urinalysis Findings

One of the earliest and most reliable signs of kidney involvement is an abnormal urinalysis. This includes the presence of hematuria (blood in the urine), proteinuria (excess protein in the urine), or microalbuminuria (small amounts of albumin not normally detected). These markers often appear before more serious structural or functional damage becomes evident, making routine urine screening a critical tool in early detection.

2. Renal Imaging Abnormalities

Changes observed through imaging studies—particularly renal ultrasound—can also support a diagnosis. For instance, increased echogenicity of the renal parenchyma may indicate inflammation or scarring in the kidneys. While imaging is less sensitive than urinalysis in early stages, it becomes more relevant when evaluating chronic changes or ruling out other causes of kidney dysfunction.

3. Impaired Kidney Function

Laboratory blood tests that reveal elevated serum creatinine, reduced glomerular filtration rate (GFR), or other biochemical signs of impaired renal function are strong indicators of established kidney injury. These abnormalities typically occur later than urinary changes, suggesting more advanced disease progression.

Recommended Screening Protocol for Early Detection

To catch HSP nephritis at its earliest stage, regular monitoring of urine is strongly advised after the last appearance of skin rash. The recommended schedule includes weekly urinalysis during the first month post-rash, biweekly testing from months two to three, and monthly checks from months four to six. Any persistent abnormality during this window should prompt further evaluation for HSP-related kidney disease.

Why early urinalysis matters: Urinary abnormalities often precede detectable changes on ultrasound or blood-based markers of kidney function. This makes simple, non-invasive urine testing the cornerstone of proactive management. Early identification allows for timely intervention, potentially preventing long-term complications such as chronic kidney disease.

In summary, diagnosing HSP nephritis in children relies on vigilant follow-up and systematic screening. By combining clinical observation with scheduled laboratory testing, healthcare providers can identify at-risk patients early and improve long-term renal outcomes.