Frequency of renal involvement in HSP?

Henoch-Schonlein purpura, also referred to as anaphylactoid purpura, is a small-vessel vasculitis characterized by palpable purpura (most commonly distributed over the buttocks and lower extremities), ahralgias, gastrointestinal signs and symptoms, and glo merulonephritis. Gastrointestinal involvement, which is seen in almost 70% of pediatric patients, is characterized by colicky abdominal pain usually associated with nausea, vomiting, diarrhea, or constipation and is frequently accompanied by the passage of blood and mucus per rectum; bowel intussusception may occur. Renal involvement occurs in 10-50% of patients and is usually characterized by mild glomerulonephritis leading to proteinuria and microscopic hematuria, with red blood cell casts in the majority of patients (Harrison&;&;s principle of internal medicine,18th edition,pg no.2797)