title: The potassium sensitivity test: a predictor of treatment response in interstitial cystitis.
abstract: OBJECTIVE
  To determine whether the potassium sensitivity test (PST) can be used to predict the response to treatment with intravesical sodium hyaluronate in patients with interstitial cystitis.
  
  
  METHODS
  Thirty-eight patients diagnosed with interstitial cystitis were recruited; each had a PST, carried out in a double-blind fashion, followed by six weekly doses of intravesical sodium hyaluronate. The patients were assessed before and after treatment using a self-administered interstitial cystitis symptom index (CSI) and problem index (PI). The clinical response was defined as none (<25% improvement in clinical symptoms), mild (>25%), moderate (50-75%) and excellent (>75%).
  
  
  RESULTS
  The PST was positive in 23 and negative or indeterminate in 13 patients; two patients withdrew from the study. Overall 20 of 36 (55%) patients reported an improvement after six doses of intravesical sodium hyaluronate, but 17 (74%) with a positive PST improved, compared to only five (22%) with a negative test (P = 0.03). There was an improvement in the CSI after treatment in both groups, but a significant improvement in the PI only in patients with a positive PST (P = 0.01). The magnitude of change for the CSI and PI was significantly greater in the positive than in the negative group (CSI, P = 0.043; PI, P < 0.001). There were no major complications. Three patients complained of pain after the test, and two with a positive and one with a negative PST developed a urinary tract infection.
  
  
  CONCLUSIONS
  Although the role of the PST in the diagnosis of interstitial cystitis requires further clarification, the test helps to predict the response to treatment with glycosaminoglycan-substitution therapy.
authors.affiliation: Urology, Arrowe Park Hospital, Wirral, Merseyside, UK. Dr_skgupta@hotmail.com
authors.forename: Suresh K
authors.initials: SK
authors.lastname: Gupta
authors.forename: Lol
authors.initials: L
authors.lastname: Pidcock
authors.forename: Nigel J
authors.initials: NJ
authors.lastname: Parr
mesh_terms: D000276:Adjuvants, Immunologic / Q000627:therapeutic use; D000328:Adult; D018856:Cystitis, Interstitial / Q000175:diagnosis* / Q000188:drug therapy; D004311:Double-Blind Method; D004334:Drug Administration Schedule; D005260:Female; D006801:Humans; D006820:Hyaluronic Acid / Q000627:therapeutic use; D007322:Instillation, Drug; D008297:Male; D008875:Middle Aged; D011189:Potassium Chloride; D012680:Sensitivity and Specificity; D018709:Statistics, Nonparametric; D016896:Treatment Outcome
chemical_list: D000276:Adjuvants, Immunologic; D011189:Potassium Chloride; D006820:Hyaluronic Acid