2240 ASYMPTOMATIC RENAL STONES IN CHILDREN TAKING TOPIRAMATE

Abstract

You have accessJournal of UrologyStone Disease: Evaluation & Medical Management1 Apr 20112240 ASYMPTOMATIC RENAL STONES IN CHILDREN TAKING TOPIRAMATE Nicol Bush, Justin Ahn, Medrith Greene, Katherine Twombley, Susan Arnold, Naim Maalouf, and Khashayar Sakhaee Nicol BushNicol Bush Dallas, TX More articles by this author , Justin AhnJustin Ahn Dallas, TX More articles by this author , Medrith GreeneMedrith Greene Dallas, TX More articles by this author , Katherine TwombleyKatherine Twombley Dallas, TX More articles by this author , Susan ArnoldSusan Arnold Dallas, TX More articles by this author , Naim MaaloufNaim Maalouf Dallas, TX More articles by this author , and Khashayar SakhaeeKhashayar Sakhaee Dallas, TX More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2011.02.2481AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Topiramate (TPM) is expected to be used in escalating proportions for treatment of various conditions, including epilepsy and migraines. TPM may cause metabolic acidosis, which can produce alkaline urine, hypocitraturia and hypercalciuria - urinary abnormalities associated with calcium phosphate stones. The drug insert reports a 1.5% incidence of stones in patients taking TPM, 2–4 times the expected rate. However, we found a 9.3% incidence in adults on long-term TPM. We screened children taking TPM to investigate prevalence and risk factors for urolithiasis. METHODS Patients up to 21 years taking TPM, identified in the pediatric neurology clinic, were administered a questionnaire evaluating TPM treatment and history and symptoms of stones. They were offered screening ultrasound and urine biochemistry unless exclusion criteria were met (history of stones, known acid/base disorder, contraindicated medications, chronic urinary infections, or renal failure). RESULTS Sixty-six children completed the questionnaire. Average age was 8.1 years (0.5–17.8 years), 40 (60%) were male, 22 (33%) were immobilized, and 17 (26%) were fed via gastrostomy tube. Twenty-four patients (36%) completed the study. One patient was excluded for known urolithiasis after starting TPM. Asymptomatic stones were found in 2 patients (8.3%) on screening ultrasound, one of whom has undergone lithotripsy. These stone-formers had an average age of 16.8 years and neither was immobilized or gastrostomy-fed; duration of TPM usage was 4 years in 1 patient and 4 months in the other. The stone-formers had higher body mass index (28.9 vs. 18.7 Kg/m2, p=0.049). Although spot urinary calcium was lower compared to non-stone-formers (449 mg vs. 98 mg, p=0.0001), the calcium/creatinine ratio was similar (0.31 vs. 0.30 mg/mg). Average urinary pH and citrate/creatinine ratio were non-significantly lower than in non-stone formers (6.03 vs. 7.04, and 0.02 vs. 0.28 mg/mg, respectively). Citrate/creatinine ratio was < 5%ile for age (<0.18) in 12 (50%) and hypercalciuria (calcium/creatine ratio > 0.2) was present in 11 (46%) children on TPM. CONCLUSIONS Asymptomatic renal stones were discovered in 2/24 (8%) children taking TPM. Risk factors for urolithiasis, including hypercalciuria and hypocitraturia, were present in nearly half. Pediatric urologists and neurologists should be aware of stone risk in patients taking TPM with a low threshold for evaluation with screening ultrasound. Further studies will hopefully help identify patients on TPM at highest risk for stones. © 2011 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 185Issue 4SApril 2011Page: e898 Advertisement Copyright & Permissions© 2011 by American Urological Association Education and Research, Inc.MetricsAuthor Information Nicol Bush Dallas, TX More articles by this author Justin Ahn Dallas, TX More articles by this author Medrith Greene Dallas, TX More articles by this author Katherine Twombley Dallas, TX More articles by this author Susan Arnold Dallas, TX More articles by this author Naim Maalouf Dallas, TX More articles by this author Khashayar Sakhaee Dallas, TX More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...