Potassium sensitivity test (PST) as a measurement of treatment efficacy of painful bladder syndrome/interstitial cystitis: A prospective study with cyclosporine A and pentosan polysulfate sodium

Aims: Potassium sensitivity test (PST) has been used as an optional tool in diagnosing painful bladder syndrome/interstitial cystitis (PBS/IC). The role of PST in the follow-up of patients with PBS/IC is elusive. We performed PST before and after treatment of PBS/IC with cyclosporine A (CyA) or pentosan polysulfate sodium (PPS), to test whether the result of repeated PST correlates with alleviation of PBS/IC-related symptoms. Materials and Methods: Sixty-four patients who participated in a randomized clinical study comparing CyA and PPS in the treatment of PBS/IC were recruited to the present study. Patients underavent 0.4 M PST before and after 6 months of treatment. The primary end point was a change from positive PST to negative among patients who responded to both treatments determined by global response assessment (GRA). Results: Potassium sensitivity test (PST) was more likely to change from positive to negative among patients who responded to their treatment according to GRA (P < 0.001). The PST change follows the clinical course (ICSI score, voiding frequency, VAS score), which was more beneficial in the CyA-treated patients. Conclusions: Potassium sensitivity test (PST) reflects symptom severity of PBS/IC patients. Change of pre-treatment positive PST to negative correlates well with clinical alleviation of PBS/IC-related symptoms. In patients with persistent symptoms it may be painful and does not offer additional information. Thus, we do not recommend PST to be used as a routine clinical test in monitoring of PBS/IC treatment efficacy.