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Paper text:
his medical history was relevant for profound developmental delay secondary to brain malformation including polymicrogyria and complex - focal seizures .
the patient was on topiramate therapy for 1.5  years ( dose : 6.5  mg / kg / day ; recommended daily dose : 39  mg / kg / day ) .
ultrasonography and plain abdominal x - ray revealed a large calcification in the left kidney ( fig.1 ) with urinary obstruction requiring the insertion of a dj - catheter .
four additional extracorporeal shockwave therapies were performed over time in order to remove all residual stone fragments . after stopping antiepileptic treatment with topiramate and starting levetiracetam treatment , no recurrence of nephrolithiasis was noted .
chronic use can lead to metabolic acidosis , hypocitraturia , hypercalciuria , and elevated urine ph , factors which increase the risk of calcium oxalate and calcium phosphate stone formation 1 . for early detection of renal complications , regular ultrasound examinations of the urinary system and special recommendation for fluid intake
key clinical messagenephrolithiasis is a less common side effect of the antiepileptic drug topiramate . 
 we report the case of a 3-year - old boy who presented to the emergency department with abdominal pain ; examinations revealed a large calcification in the left kidney . 
 regular ultrasound examinations are recommended in children using topiramate .