Gastrointestinal involvement is rarely serious
Gastrointestinal involvement has been reported in 63% of patients with HSP. Symptoms typically include a colicky abdominal pain, associated with nausea and vomiting. These symptoms probably arise secondary to edema of the bowel wall and vasculitis of the gastrointestinal tract. The pain most often develops within 8 days of the appearance of the rash, but it has been reported to appear within weeks to months of cutaneous changes.12
Intussusception is the most common gastrointestinal complication in patients with HSP, with a reported overall incidence of 3.5% in hospitalized patients with severe abdominal pain. Gastrointestinal bleeding, presenting as either melena or hematochezia, has been reported in 25% of patients with HSP. Occult bleeding may occur in up to 50% of patients.12
More serious complications are rare, and they include bowel infarction and perforation, usually in the jejunum or ileum, and pancreatitis, cholecystitis, or protein-losing enteropathy secondary to HSP.
Renal involvement may require close follow-up
Renal disease has been reported to affect 30% to 70% of all HSP patients.13 Onset occurs within weeks to months after other symptoms of HSP. Most patients with renal involvement have only mild disease, such as asymptomatic hematuria and proteinuria.1,7,13 HSP is thought to account for approximately 15% of all glomerulopathies in childhood.13
Although renal disease in HSP is generally benign, such complications as nephrotic syndrome, hypertension, and acute and chronic renal failure may occur. Adults are much more susceptible to the latter complication.
When the diagnosis is unclear, renal biopsy may help confirm the presence of disease. Evidence of HSP is identical to that seen with IgA nephropathy.11,13 The percentage of glomeruli showing crescents on renal biopsy seems to be the most important prognostic finding, with crescent formation involving more than 50% of the glomeruli carrying a poor prognosis.14
Diagnosis is mainly clinical
Clinical diagnosis is not difficult with the classic 4 symptoms present (rash, abdominal pain, arthralgia, and evidence of renal involvement). However, when the presentation is less straightforward, confirmation of the diagnosis may depend on biopsy of the affected organ (eg, skin, kidney) demonstrating leukocytoclastic vasculitis with IgA deposition.
The differential diagnosis of HSP is large, and includes acute abdomen, meningococcal meningitis or septicemia, rheumatoid arthritis, idiopathic thrombocytopenic purpura, and systemic lupus erythematosus.15
Lab tests are minimally helpful. No lab test or imaging study is sensitive or specific for HSP. An elevated serum IgA level suggests the disease. A CBC may show leukocytosis and thrombocytosis, but test results may also be normal. The erythrocyte sedimentation rate may be elevated. On a BMP, blood urea nitrogen and creatinine levels may be elevated secondary to renal involvement or dehydration associated with HSP. Finally, hematuria or proteinuria show up on urinalysis in 30% to 70% of patients with HSP.2,12,13
What treatment is indicated?
Most patients with HSP recover completely without any specific intervention other than reassurance, bed rest, and supportive care. Arthralgia usually responds to nonsteroidal anti-inflammatory drugs and corticosteroids. Hospitalization is warranted when patients have a depleted volume status or inadequately controlled pain. With an otherwise un-complicated illness, watchful management suffices. Gastrointestinal and renal complications may require more aggressive therapy.
Gastrointestinal complications. As noted earlier, the most common gastrointestinal complication is intussusception. No definite measures for preventing intussusception appear in the literature. Some evidence supports the use of corticosteroids for severe abdominal symptoms,16,17 but in general, corticosteroids are not indicated for extrarenal manifestations. More serious complications such as bowel infarction or perforation, pancreatitis, or cholecystitis are rare.
Renal disease. Much research has focused on treatment options for patients with renal complications, due to the possibility of long-term debilitating effects. Although no evidence supports corticosteroid use for patients with mild renal involvement,16 for patients with severe renal disease—defined as crescenteric nephritis on biopsy, usually complicated by oliguria and hypertension—corticosteroids may help prevent irreversible glomerular injury.
Other agents that have been used for severe renal disease include azathioprine, cyclophosphamide, and dipyridamole. These drugs have shown some success in resolving symptoms, but their use remains controversial.16,18 Finally, plasmapheresis has led to significant clinical improvement for a small number of patients with severe, rapidly progressing HSP.
Caveat. The effectiveness of all treatments for HSP remains in question, given that patients’ symptoms may simply resolve spontaneously. A clear answer will depend on further research.
Rest, fluids, and ibuprofen for your patient
You send your patient home with his mother, and advise her to provide him with supportive care, including oral hydration. You tell her to encourage rest and to give symptomatic pain relief with an over-the-counter medication such as ibuprofen.