Urolithiasis induced by combined ACTH and zonisamide treatment in a patient with startle induced epilepsy

: A 5-year-old boy had periodic spasms and startle-induced drop attacks. Zonisamide (ZNS) was partially effective for the former seizures, and propranolol for the latter. An add-on therapy with ACTH resulted in a transient disappearance of seizures and an improvement of EEG. However, the patient developed urolithiasis with resultant hematuria and pyelectasis during ACTH therapy. ZNS can induce urolithiasis by increasing urinary pH and calcium (Ca) excretion, and ACTH may facilitate this rare adverse effect of ZNS by further increasing the urinary Ca. Hydrochlorothiazide could resolve the urolithiasis by decreasing the urinary Ca excretion.