title: Prevalence and spot urine risk factors for renal stones in children taking topiramate.
abstract: BACKGROUND
  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.
authors: 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. Electronic address: nicol.bush@childrens.com.
authors: Nicol
authors: N
authors: Corbin Bush
authors: Katherine
authors: K
authors: Twombley
authors: Justin
authors: J
authors: Ahn
authors: Carlos
authors: C
authors: Oliveira
authors: Susan
authors: S
authors: Arnold
authors: Naim M
authors: NM
authors: Maalouf
authors: Khashayar
authors: K
authors: Sakhaee
mesh_terms: D000293:Adolescent; D000468:Alkalies / Q000652:urine; D000927:Anticonvulsants / Q000009:adverse effects*; D002118:Calcium / Q000652:urine; D002648:Child; D002675:Child, Preschool; D019343:Citric Acid / Q000652:urine; D003404:Creatinine / Q000652:urine; D004827:Epilepsy / Q000188:drug therapy* / Q000453:epidemiology; D005260:Female; D005632:Fructose / Q000009:adverse effects / Q000031:analogs & derivatives*; D006801:Humans; D053565:Hypercalciuria / Q000139:chemically induced / Q000453:epidemiology / Q000652:urine; D007223:Infant; D007669:Kidney Calculi / Q000139:chemically induced* / Q000453:epidemiology* / Q000652:urine; D008297:Male; D015995:Prevalence; D011446:Prospective Studies; D012307:Risk Factors; D000077236:Topiramate
chemical_list: D000468:Alkalies; D000927:Anticonvulsants; D000077236:Topiramate; D019343:Citric Acid; D005632:Fructose; D003404:Creatinine; D002118:Calcium
keywords: Epileptic; Kidney stones; Prevalence; Topiramate; Urolithiasis
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