Risk of Kidney Damage in HSP from Childhood
Patients who had severe renal involvement at HSP onset in childhood face a 35% risk of renal impairment in adulthood after 24 years, compared to only 7% risk for those with mild or no renal symptoms initially. 1
Long-Term Renal Outcomes Based on Initial Presentation
The risk of kidney damage decades after childhood HSP is directly tied to the severity of initial renal involvement:
- No renal symptoms at onset: 100% had good outcomes after 24 years of follow-up 1
- Mild renal symptoms at onset: 7% developed renal impairment as adults 1
- Severe glomerulonephritis at onset: 35% developed renal impairment as adults (relative risk 4.7) 1
- Nephrotic-nephritic syndrome combination at onset: Over 50% risk of chronic renal failure after 20 years 2
Women face higher risk than men, with a relative risk of 5.0 for poor outcomes compared to 2.0 in men 1.
Critical Time Window for Renal Involvement
Renal disease occurs in 40-50% of all HSP patients during the acute phase 3. However, renal signs can become manifest years after initial HSP presentation, making the diagnosis easy to miss if follow-up is inadequate 2. This delayed presentation underscores why lifelong vigilance is necessary even in patients who appeared to have mild disease initially.
End-Stage Renal Disease Risk
The overall risk of end-stage renal disease is 1-5% across all HSP patients 3. However, this risk is not evenly distributed—it concentrates heavily in those with severe initial renal involvement 1, 2.
Special Considerations for Women
Women with any history of childhood HSP face substantial pregnancy-related complications: 70% of pregnancies were complicated by hypertension, proteinuria, or both 1. Among women with complicated pregnancies, 56% had poor renal outcomes 1. Therefore, all women with even mild renal symptoms at HSP onset require careful monitoring during and after pregnancy 1, 4.
Monitoring Requirements
Follow-up for at least 6 months is mandatory for all children presenting with HSP, including regular urine testing for proteinuria and hematuria plus blood pressure measurement 4. However, given that renal manifestations can appear years later and that silent chronic renal failure can develop after decades 2, long-term follow-up of all patients who had severe renal symptoms at onset is needed during adulthood 1.
The severity of the first kidney biopsy finding does not reliably predict long-term outcome 1, making clinical monitoring more important than histological grading for prognostication.
Common Pitfall to Avoid
Do not assume that complete clinical recovery from acute HSP nephritis eliminates future risk—the risk persists even for patients who apparently completely recovered from renal disease 2. This is why lifelong surveillance is recommended for anyone with initial renal involvement.