Overview
Definition:
Henoch-Schönlein Purpura (HSP), also known as IgA vasculitis, is the most common childhood systemic vasculitis, characterized by a tetrad of palpable purpura, arthritis/arthralgia, abdominal pain, and renal disease
Renal involvement, termed HSP nephritis (HSPN), is a significant complication that requires careful and prolonged follow-up to monitor for progression and potential long-term sequelae.
Epidemiology:
HSP typically affects children aged 3-10 years, with a male predominance
Incidence varies, but it is estimated to occur in approximately 10-20 cases per 100,000 children annually
Renal involvement is seen in 25-60% of affected children, with severe renal disease occurring in about 1-2%.
Clinical Significance:
HSPN can range from mild, self-limiting proteinuria and hematuria to rapidly progressive glomerulonephritis (RPGN) leading to end-stage renal disease (ESRD)
A structured renal follow-up protocol is crucial for early detection of worsening renal function, timely intervention, and prevention of irreversible renal damage, making it a key area of focus for DNB and NEET SS preparation.
Clinical Presentation Of Hspn
Symptoms:
Hematuria, often microscopic and persistent
Proteinuria, ranging from trace to nephrotic range
Edema, particularly periorbital and in lower extremities if nephrotic syndrome develops
Hypertension can occur in severe cases
Abdominal pain, vomiting, or diarrhea preceding or accompanying renal symptoms.
Signs:
Palpable purpura, typically on lower extremities and buttocks
Arthritis or arthralgia, especially in knees and ankles
Abdominal tenderness on palpation
Edema
Hypertension detected on vital sign monitoring.
Diagnostic Criteria:
The typical presentation includes a purpuric rash, arthralgia, abdominal pain, and renal disease, although not all features may be present simultaneously
Diagnosis is primarily clinical, supported by biopsy findings (dermal or renal) showing IgA deposition
Renal biopsy is indicated for significant proteinuria (>1g/day or >200mg/mmol creatinine), persistent hematuria with active urinary sediment, or rising creatinine.
Diagnostic Approach To Hspn
History Taking:
Detailed history of preceding upper respiratory tract infection or other trigger
Onset and progression of rash, joint pain, abdominal symptoms, and urinary changes
History of gross hematuria, edema, or hypertension
Prior renal history or family history of kidney disease
Medications and allergies.
Physical Examination:
Thorough dermatological assessment focusing on the distribution and morphology of the purpura
Assessment of joints for inflammation and range of motion
Careful abdominal examination for tenderness, masses, or organomegaly
Evaluation for edema and vital signs, including blood pressure measurement.
Investigations:
Urinalysis: microscopic hematuria (dysmorphic red blood cells, red cell casts) and proteinuria
24-hour urine protein or urine protein-to-creatinine ratio (UPCR): to quantify proteinuria
Serum creatinine and BUN: to assess renal function
Complete blood count (CBC): may show anemia or elevated platelets
Inflammatory markers (ESR, CRP): usually elevated during acute phase
Serum IgA levels: often elevated but not diagnostic
Renal biopsy: gold standard, showing mesangial IgA deposition, often with varying degrees of glomerulonephritis (mesangial proliferative, focal proliferative, membranoproliferative, or crescentic GN).
Differential Diagnosis:
Other causes of vasculitis (e.g., ANCA-associated vasculitis)
Thrombocytopenic purpura (e.g., ITP, TTP)
Allergic purpura
Idiopathic thrombocytopenic purpura
Drug-induced purpura
Infectious causes of purpura
Other causes of glomerulonephritis.
Renal Follow Up Protocol
Initial Assessment And Monitoring:
All children with HSP should have urinalysis and serum creatinine checked at diagnosis
Regular monitoring intervals are crucial, especially in the first 6 months
Initial follow-up typically includes urinalysis and serum creatinine every 1-2 weeks for the first month, then monthly for up to 6 months
If stable, frequency can be reduced to every 3-6 months.
Investigation Frequency And Indications:
Urinalysis (hematuria, proteinuria) and serum creatinine should be performed at each visit
Urine protein-to-creatinine ratio (UPCR) or 24-hour urine protein should be done at baseline, at 1 month, and then every 3-6 months if proteinuria persists or is significant
Blood pressure monitoring is essential at every visit
Renal ultrasound may be considered if renal function deteriorates or to rule out other causes of renal pathology.
Duration Of Follow Up:
Follow-up should continue for at least 5 years after diagnosis, as late relapses or progression can occur
Some guidelines recommend follow-up for up to 10 years, especially in patients with moderate to severe renal involvement or persistent abnormalities
Even after achieving normal values, annual urinalysis for several years is prudent.
Management During Follow Up:
Mild renal involvement (microscopic hematuria, mild proteinuria) may only require supportive care and close monitoring
Moderate to severe renal involvement (significant proteinuria, nephrotic syndrome, impaired renal function, or crescents on biopsy) may warrant treatment with corticosteroids (e.g., prednisolone), immunosuppressants (e.g., azathioprine, mycophenolate mofetil), or ACE inhibitors/ARBs for proteinuria and hypertension
Treatment decisions are based on severity and biopsy findings.
Biopsy Indications During Follow Up:
A repeat renal biopsy may be considered if there is significant deterioration of renal function, persistent or worsening proteinuria (>1g/day or >200mg/mmol creatinine), or development of nephrotic syndrome or significant hypertension after initial presentation, especially if not responding to treatment
This helps re-evaluate the extent of glomerular damage and guide further management.
Management Of Hspn
Initial Management:
Supportive care is paramount, including hydration, pain management for arthritis, and dietary modifications if necessary
For mild renal involvement (isolated hematuria/proteinuria), observation and symptomatic treatment are usually sufficient
Early initiation of ACE inhibitors or ARBs is recommended for significant proteinuria (>0.5g/day) or hypertension, irrespective of renal function.
Medical Management:
Corticosteroids: typically used for significant proteinuria, nephrotic syndrome, or evidence of active inflammation (e.g., crescents on biopsy)
Prednisolone is the usual agent, with doses and duration varying based on severity
Immunosuppressants: Azathioprine, mycophenolate mofetil, cyclophosphamide may be considered for severe or refractory cases, particularly those with crescents or RPGN
Angiotensin-converting enzyme (ACE) inhibitors or Angiotensin II receptor blockers (ARBs): recommended for all patients with persistent proteinuria (>0.5g/day) or hypertension to reduce long-term renal damage.
Surgical Management:
Surgery is not a primary treatment for HSPN
Surgical intervention may be considered only for complications like intussusception if present, but this is separate from the renal management.
Supportive Care:
Adequate hydration and fluid management are important
Management of hypertension with antihypertensive medications
Nutritional support if nephrotic syndrome is present
Monitoring for infections and their prompt treatment, as infections can precipitate relapses.
Complications And Prognosis
Early Complications:
Acute kidney injury (AKI), severe hypertension, nephrotic syndrome with edema and electrolyte imbalances, gastrointestinal bleeding or perforation, orchitis.
Late Complications:
Chronic kidney disease (CKD), end-stage renal disease (ESRD), hypertension, recurrent episodes of HSPN, which can cumulatively lead to progressive renal damage.
Factors Affecting Prognosis:
Severity of initial renal involvement is the most important prognostic factor
Features associated with poor prognosis include heavy proteinuria (>1g/day or >200mg/mmol creatinine), nephrotic syndrome, hypertension, elevated serum creatinine at diagnosis, and crescent formation (>50% glomeruli) on renal biopsy
Age at onset and duration of symptoms before diagnosis also play a role.
Outcomes:
Most children with mild HSPN fully recover renal function
Approximately 20-30% may have persistent proteinuria or hematuria
Around 5-10% develop progressive CKD, and a small percentage (<2%) progress to ESRD
Long-term follow-up is essential to identify these individuals early.
Prevention Strategies:
Prompt recognition and management of initial HSPN symptoms are key
Adherence to recommended treatment protocols for moderate to severe renal disease
Long-term use of ACE inhibitors/ARBs in patients with persistent proteinuria
Regular monitoring and early intervention for any signs of renal deterioration.
Key Points
Exam Focus:
Key for DNB/NEET SS: Know the diagnostic criteria for HSP, common presentations of HSPN (hematuria, proteinuria, edema, hypertension), indications for renal biopsy, and the cornerstone investigations in renal follow-up (urinalysis, UPCR, serum creatinine, BP monitoring)
Understand the risk factors for poor renal outcome and the role of ACE inhibitors/ARBs.
Clinical Pearls:
Always check urinalysis and serum creatinine in all children with HSP
Palpable purpura on dependent areas in a child with abdominal pain and joint pain should raise suspicion for HSP
Renal biopsy findings are crucial for stratifying risk and guiding treatment
Do not stop ACE inhibitors/ARBs for mild proteinuria, they are renoprotective.
Common Mistakes:
Underestimating the risk of renal involvement in HSP
Inadequate duration or frequency of renal follow-up
Delaying renal biopsy when indicated
Not initiating ACE inhibitors/ARBs in the presence of proteinuria or hypertension
Failing to monitor blood pressure regularly.