urolithiasis; acidosis; renal tubular acidosis; topiramate; glomerular filtration rate

Introduction: The aim of this study is to present a case of 44 years old woman with topiramate induced metabolic acidosis and kidney stones.Materials and methods: The laboratory features of topiramate caused renal tubular acidosis in blood and urine during topiramate treatment, with correction of metabolic acidosis by potassium citrate, and after topiramate withdrawal are presented. Differential diagnosis of all possible causes of metabolic acidosis is discussed.Results: The results revealed negative base excess in extracellular fluid of - 9.2 mmol/L, low serum HCO3- concentration (18.6 mmol/L), trend to alkaline urine (pH 6.39) and low urine citrate concentration (0.3 mmol/24h). After topiramate withdrawal, all parameters of the internal environment normalized.Conclusions: This study has shown that long-term topiramate administration could induce metabolic acidosis and consequently urholithiasis. Thus, we could recommend testing blood acid base balance, urinary pH and citrates in patients taking topiramate and suffering from kidney stones.