Abstract
Urolithiasis rarely develops in children and is often associated with underlying conditions, such as idiopathic hypercalciuria, renal tubular acidosis, hypervitaminosis, and congenital metabolic disorders. Henoch-Schönlein purpura (HSP) is characterized by systemic small vessel vasculitis and is frequently complicated by colicky abdominal pain for which corticosteroid is very effective. We present unusual case of an 8-year-old boy with HSP complicated by bilateral ureteral obstruction due to urolithiasis. He was referred to us because of severe abdominal pain and bloody stool with the diagnosis of HSP on the 7th day of illness. As his abdominal pain was intractable, prednisolone had been administered for 2 weeks. At this point, vitamin D (alpfacalcidol) supplementation was initiated to prevent steroid induced osteoporosis. Eighteen days after the addition of vitamin D, he suffered backache, presented hematuria and anuria: based on the laboratory findings and imaging studies, the diagnosis of acute kidney injury (AKI) due to bilateral ureteral obstruction caused by urolithiasis was made. AKI improved rapidly by unilateral nephrostomy and ureteral stenting and he was discharged on the 59th day of illness without any sequelae. It is well known that vitamin D promotes intestinal absorption of calcium and increases its urinary excretion. In fact, our patient demonstrated the increased urinary levels of calcium since initiation of vitamin D supplementation. It is also reported that ureteritis due to periureteral vasculitis occasionally develops in patients with HSP. Taken together, we considerd that ureteral obstruction caused by urolithiasis in this boy was strongly associated with vitamin D supplementation as well as ureteral stenosis due to HSP. Therefore, lithogenic agents, such as vitamin D should be administered with caution in children with HSP.
