What is the next step for a patient with a rash extending to the buttocks, who is hemodynamically stable and has a negative urine dipstick?

Henoch-Schönlein Purpura (IgA Vasculitis): Follow-Up for Renal Involvement

The appropriate next step is A - Follow-up for renal involvement. This patient presents with a classic palpable purpuric rash extending to the buttocks in a hemodynamically stable state with negative initial urine dipstick, which is consistent with Henoch-Schönlein Purpura (HSP), also known as IgA vasculitis. Despite the negative initial urinalysis, renal involvement can develop later in the disease course and requires systematic monitoring.

Why Follow-Up for Renal Involvement is Critical

• HSP is characterized by a palpable purpuric rash that typically involves the lower extremities and buttocks, often accompanied by arthralgia, abdominal pain, and potential renal involvement 1
• Renal complications can develop weeks to months after the initial presentation, even when the initial urinalysis is negative 1
• A negative urine dipstick at presentation does not exclude future renal involvement, as glomerulonephritis may manifest later in the disease course 1
• Microscopic hematuria and proteinuria are the most common renal manifestations of HSP, and serial monitoring is essential to detect these early 1

Monitoring Protocol

• Repeat urinalysis should be performed at regular intervals for at least 6 months after diagnosis, as renal involvement may be delayed 1
• Both microscopic examination and dipstick testing should be used, as dipstick alone may miss early glomerular disease 1
• Blood pressure monitoring is essential, as hypertension may indicate progressive renal involvement 1
• If hematuria or proteinuria develops, nephrology referral is warranted for further evaluation and potential renal biopsy 1

Why the Other Options Are Incorrect

B - Avoid Sports

• There is no evidence-based recommendation to restrict physical activity in stable HSP patients without complications 1
• Activity restriction would only be considered if there were evidence of severe systemic involvement such as significant abdominal complications or severe renal disease 1

C - Avoid Vaccination

• Vaccination is not contraindicated in HSP, and there is no guideline recommending vaccine avoidance 1
• HSP is not an immunodeficiency state, and routine immunizations can proceed once the acute phase resolves 1

D - Oral Antibiotics

• HSP is a vasculitic process, not an infectious disease requiring antibiotics 1
• Antibiotics would only be indicated if there were evidence of secondary bacterial infection, which is not suggested by the clinical presentation 2
• The negative urine dipstick and stable vital signs argue against urinary tract infection as a concurrent diagnosis 2

Common Pitfalls to Avoid

• Do not assume a single negative urinalysis rules out renal involvement - serial monitoring is mandatory 1
• Do not delay follow-up based on initial stability - renal complications can be insidious and progressive 1
• Do not confuse the purpuric rash with simple petechiae - HSP produces palpable purpura due to leukocytoclastic vasculitis, which has different implications than thrombocytopenic purpura 3
• Do not overlook the buttock distribution as a key diagnostic feature - this distribution pattern is highly characteristic of HSP and helps distinguish it from other causes of rash 1, 3