BMJ Case Reports 2018; doi:10.1136/bcr-2018-225697
  • Unexpected outcome (positive or negative) including adverse drug reactions

Effect of topiramate on sweat chloride level while screening for cystic fibrosis

  1. Gavin Graff3
  1. 1Department of Pediatrics, Penn State Health Milton S Hershey Medical Center, Hershey, Pennsylvania, USA
  2. 2Department of Pediatrics, St Christophers Hospital for Children, Philadelphia, USA
  3. 3Department of Pediatrics, Penn State Health Milton S Hershey Medical Center, Hershey, Pennsylvania, USA
  1. Correspondence to Dr Roopa Siddaiah, rsiddaiah{at}
  • Accepted 17 August 2018
  • Published 5 September 2018


Cystic fibrosis is the most common life-limiting genetic condition in Caucasians caused by Cystic Fibrosis Transmembrane conductance Regulator (CFTR) gene mutations. Sweat chloride is the current gold standard for diagnosis where values >60 mmol/L are diagnostic and values >30 mmol/L are indeterminate. There is limited literature on the effect of medications on the sweat chloride values. We report a case of topiramate being responsible for false-positive testing which resulted in overutilisation of medical resources and psychosocial stress on the family. Topiramate should be considered during the interpretation of the gold standard testing as one of the cause of false-positive sweat tests.


  • Contributors RS: drafted the initial manuscript, revised and approved the final manuscript as submitted. ET: helped draft the initial manuscript and worked on the tables and figures included in the manuscript, reviewed the manuscript and approved the final manuscript as submitted. GG: mentored and provided critical reviews and revisions to the manuscript, and approved the final manuscript as submitted. All authors approved the final manuscript as submitted and agree to be accountable for all aspects of the work.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Patient consent Obtained.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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