INTRODUCTION: Topiramate (TPM), an anti-epileptic drug with >4 million users, increases renal stones in adults.
We screened outpatient TPM-treated children without history of stones to estimate the prevalence of renal stones and to characterize urine stone-risk profiles.
METHODS: Children taking TPM ≥1 month underwent an interview, renal ultrasound, and spot urine testing in this prospective study. Normal spot urine values were defined as: calcium/creatinine ratio ≤ 0.20 mg/mg (>12 months) or ≤ 0.60 mg/mg (≤ 12 months), citrate/creatinine ratio >0.50 mg/mg, and pH ≤ 6.7.
RESULTS: Of 41 patients with average age of 9.2 years (range 0.5-18.7), mean TPM dose of 8.0 mg/kg/day (range 1.4-23.6), and mean treatment duration of 27 months (range 1-112), two (4.9%) had renal stones. The majority of children taking TPM had lithogenic abnormalities on spot urine testing, including 21 (51%) with hypercalciuria, 38 (93%) with hypocitraturia, and 28 (68%) with pH ≥ 6.7. Hypercalciuria and hypocitraturia were independent of TPM dose and duration; urine pH increased with dose. 24-h urine parameters improved in 1 stone-former once TPM was weaned.
CONCLUSIONS: Asymptomatic stones were found in 2/41 (4.8%) children taking TPM. Risk factors for stones were present in the spot urine of most children, including hypocitraturia (93%) and hypercalciuria (51%), independent of TPM dose and duration. High urine pH, found in 68%, correlated with TPM dose. Pediatric specialists should be aware of increased risks for stones, hypercalciuria, hypocitraturia, and alkaline urine in children taking TPM.
Written by:
Corbin Bush N, Twombley K, Ahn J, Oliveira C, Arnold S, Maalouf NM, Sakhaee K. Are you the author?
University of Texas Southwestern Medical Center, Dallas, TX, USA; Children's Medical Center Dallas, Dallas, TX, USA; Department of Urology/Division of Pediatric Urology, Dallas, TX, USA.
Reference: J Pediatr Urol. 2013 Jan 31. pii: S1477-5131(12)00297-5.
doi: 10.1016/j.jpurol.2012.12.005
PubMed Abstract
PMID: 23375465
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