Overview
Definition:
Henoch–Schönlein purpura (HSP), now often referred to as IgA vasculitis (IgAV), is a systemic vasculitis characterized by the deposition of IgA-containing immune complexes in small blood vessels
Renal involvement, or HSP nephritis, is the most common serious complication and a significant cause of morbidity, affecting 20-60% of affected children
It is typically a self-limiting condition but can progress to chronic kidney disease or end-stage renal failure in a minority of cases.
Epidemiology:
HSP is the most common systemic vasculitis of childhood, with an incidence of approximately 10-20 per 100,000 children per year
It most frequently affects children between the ages of 3 and 10 years, with a bimodal peak in early childhood and adolescence
Boys are affected slightly more often than girls
Renal involvement is more common in older children and those with more severe initial symptoms
Triggering events such as upper respiratory tract infections are identified in up to 50% of cases.
Clinical Significance:
Monitoring for and managing renal involvement in HSP is critical for preventing long-term renal sequelae
Early recognition of nephritis and prompt, appropriate management can significantly improve the prognosis and reduce the risk of chronic kidney disease
Understanding the diagnostic criteria, monitoring parameters, and treatment strategies for HSP nephritis is therefore essential for pediatricians and residents preparing for DNB and NEET SS examinations.
Clinical Presentation
Symptoms:
Typical presentation includes palpable purpura, most often on the lower extremities and buttocks
Arthralgia or arthritis, abdominal pain, and renal involvement
Renal symptoms may range from asymptomatic microscopic hematuria and proteinuria to macroscopic hematuria, edema, hypertension, and acute kidney injury
Onset of nephritis can be concurrent with other symptoms, delayed by days to weeks, or, rarely, precede the rash.
Signs:
Palpable purpura is the hallmark physical finding
Examination may reveal joint swelling and tenderness, particularly in the ankles and knees
Abdominal tenderness can be present, sometimes mimicking acute surgical abdomen
Signs of renal involvement include peripheral edema, hypertension, and in severe cases, signs of fluid overload
Overt renal failure may present with lethargy and decreased urine output.
Diagnostic Criteria:
Diagnosis of HSP is typically made clinically based on the presence of palpable purpura plus at least one of the following: arthritis/arthralgia, abdominal pain, or renal involvement
For renal involvement, evidence of glomerulonephritis on biopsy or significant abnormalities in urine tests (hematuria, proteinuria) are key
While a renal biopsy is not always necessary for diagnosis, it is crucial for prognostication and guiding management in moderate to severe cases
The revised ACR/EULAR criteria for IgAV are also relevant, requiring palpable purpura plus at least one of: (1) age <= 20 years, (2) renal involvement, (3) arthritis, (4) gastrointestinal involvement, (5) biopsy showing IgA deposition.
Diagnostic Approach
History Taking:
Detailed history should focus on the onset, duration, and characteristics of the rash
presence of joint pain or swelling
abdominal symptoms (pain, vomiting, bleeding)
recent infections (especially upper respiratory)
and any family history of vasculitis or kidney disease
Inquire about any medications or allergies.
Physical Examination:
A thorough physical examination is essential
Systematically examine the skin for purpura, noting its distribution and morphology
Assess for joint swelling and tenderness
Palpate the abdomen for tenderness and organomegaly
Measure blood pressure carefully, as hypertension is a key indicator of renal involvement
Assess for peripheral edema and signs of fluid overload.
Investigations:
Initial investigations should include a complete blood count (CBC) with differential, platelet count, renal function tests (serum creatinine, BUN), electrolytes, urinalysis (dipstick and microscopy for red blood cells, white blood cells, casts, and protein), and coagulation profile
Urinalysis is crucial for detecting microscopic hematuria, proteinuria, and red blood cell casts, which are indicative of glomerulonephritis
A spot urine protein-to-creatinine ratio (UPCR) or albumin-to-creatinine ratio (UACR) is more quantitative for proteinuria
Elevated serum creatinine or BUN indicates impaired renal function
Serum IgA levels may be elevated but are not diagnostic
Renal biopsy is indicated for significant proteinuria (>1 g/day or UPCR > 100 mg/mmol), persistent hematuria, declining renal function, or hypertension suggestive of severe nephritis.
Differential Diagnosis:
Other causes of purpura and abdominal pain in children include idiopathic thrombocytopenic purpura (ITP), thrombotic thrombocytopenic purpura (TTP), hemolytic uremic syndrome (HUS), meningococcemia, other forms of vasculitis (e.g., ANCA-associated vasculitis, lupus nephritis), Henoch-Schönlein purpura due to other triggers, and allergic reactions
Differentiating HSP nephritis from other glomerulonephritides like post-infectious glomerulonephritis, IgA nephropathy, and lupus nephritis is important, often requiring a renal biopsy.
Management
Initial Management:
Management is largely supportive, focusing on symptom relief and preventing complications
For mild cases without significant renal involvement, supportive care including rest, hydration, and NSAIDs (with caution if GI symptoms are severe) is usually sufficient
Antihypertensives are started if blood pressure is elevated
Adequate hydration is important to maintain renal perfusion.
Medical Management:
For renal involvement: Mild nephritis (isolated microscopic hematuria/proteinuria < 0.5 g/day) may be managed with supportive care and close monitoring
Moderate nephritis (proteinuria 0.5-3 g/day, microscopic hematuria, normal renal function) often warrants treatment with corticosteroids, typically prednisone 1-2 mg/kg/day (max 60 mg/day), tapered over 4-8 weeks
Severe nephritis (proteinuria > 3 g/day, significant hematuria, declining renal function, hypertension) may require more aggressive therapy, including pulsed methylprednisolone followed by oral corticosteroids, and sometimes immunosuppressants like azathioprine or mycophenolate mofetil
ACE inhibitors or ARBs are recommended for patients with significant proteinuria (>1 g/day) or hypertension to reduce proteinuria and protect renal function.
Surgical Management:
Surgical intervention is not a primary treatment for HSP or its nephritis
However, surgical management might be considered for complications such as intussusception, which can occur in HSP and may require reduction or resection.
Supportive Care:
Supportive care includes pain management for arthralgias, monitoring of fluid balance and blood pressure, dietary modifications (e.g., salt restriction if hypertensive), and education for parents regarding the disease course and follow-up
Close monitoring of urine output and signs of edema is vital.
Complications
Early Complications:
Early complications can include severe abdominal pain leading to intussusception or intestinal perforation, testicular torsion (in boys), pancreatitis, and acute kidney injury (AKI) from severe glomerulonephritis
Hemorrhagic complications can occur, although typically mild.
Late Complications:
The most significant late complication is the development of chronic kidney disease (CKD) or end-stage renal disease (ESRD)
Hypertension and persistent proteinuria are indicators of a poorer prognosis
Recurrence of HSP is possible, though usually less severe
Long-term sequelae can include glomerulosclerosis, interstitial fibrosis, and crescent formation on renal biopsy.
Prevention Strategies:
While the primary vasculitic process cannot be prevented, early recognition and aggressive management of significant renal involvement are key to preventing progression to CKD
Adherence to prescribed medications and regular follow-up are crucial
Prompt treatment of hypertension and proteinuria with ACE inhibitors/ARBs may help preserve renal function.
Prognosis
Factors Affecting Prognosis:
Prognostic factors for renal involvement include the severity of nephritis at presentation (proteinuria >1 g/day, presence of renal insufficiency, hypertension), histological findings on renal biopsy (e.g., diffuse proliferative or crescentic glomerulonephritis), and promptness and adequacy of treatment
Children presenting with only microscopic hematuria and proteinuria have an excellent prognosis.
Outcomes:
Approximately 80-90% of children with HSP nephritis recover completely without long-term renal sequelae
About 10-20% may develop some degree of chronic kidney disease, and a smaller proportion (<5%) progress to end-stage renal disease requiring dialysis or transplantation
Long-term follow-up is essential for all children with renal involvement.
Follow Up:
Children with confirmed renal involvement in HSP require prolonged follow-up, typically for at least 2-5 years, or until urinalysis and renal function normalize
This includes regular monitoring of blood pressure, urine protein (UPCR/UACR), and serum creatinine
Periodic reassessment of renal function is recommended even after apparent recovery, as some patients may develop late-onset CKD.
Key Points
Exam Focus:
HSP nephritis is IgA-mediated
Key diagnostic triad: palpable purpura, arthralgia, abdominal pain
Renal involvement is common (20-60%) and the main cause of morbidity
Urinalysis is critical: hematuria, proteinuria, RBC casts
Renal biopsy essential for severe nephritis (UPCR > 100 mg/mmol, AKI, hypertension)
Management depends on nephritis severity: supportive, corticosteroids, ACEi/ARBs
Poor prognostic factors: severe proteinuria, AKI, hypertension, diffuse proliferative/crescentic GN on biopsy.
Clinical Pearls:
Always check urinalysis in children with suspected HSP, even if asymptomatic
Don't forget to measure blood pressure
hypertension is a red flag for renal involvement
ACE inhibitors/ARBs are nephroprotective for significant proteinuria/hypertension
Consider surgical causes for abdominal pain in HSP (intussusception, perforation) but remember it's a complication, not a treatment
Renal biopsy findings guide prognosis and treatment intensity.
Common Mistakes:
Underestimating the significance of mild renal findings
Delaying or undertreating significant nephritis
Forgetting to measure blood pressure
Not performing renal biopsy when indicated for prognostication
Failing to initiate ACE inhibitors/ARBs in proteinuric or hypertensive patients
Inadequate long-term follow-up for patients with renal involvement.