Potassium leak test predicts outcome in interstitial cystitis.

Abstract

We tested whether the potassium leak test predicts the outcome of therapy with heparinoids and antidepressants in interstitial cystitis. We retrospectively reviewed the records of 38 evaluable patients with interstitial cystitis who underwent a potassium leak test at the initial evaluation and who were treated intravesically with heparin or oral sodium pentosan polysulfate for a minimum of 6 months. All but 1 patient were also treated with tricyclic antidepressants. Changes in average pain score during voiding, urinary frequency and nocturia were evaluated. The potassium leak test was positive and negative in 23 and 15 patients, respectively. There was no significant difference in the 2 groups at baseline in regard to the male-to-female ratio, patient age, years of symptoms, pain score, urinary frequency, nocturia or anesthetic capacity. After a minimum of 6 months of therapy patients in whom the potassium leak test was positive were more likely to have improvement than those in whom it was negative, as shown by a decrease of greater than 25% in pain score (78 versus 40%, p = 0.01), frequency (83 versus 47%, p = 0.02) and nocturia (83 versus 53%, p = 0.05). However, potassium leak test results showed no significant difference at the 50% decrease level in pain score, frequency or nocturia. The potassium leak test may predict outcome in patients with interstitial cystitis who are treated with combined heparinoid and tricyclic antidepressant medication.