Abnormal sensitivity to intravesical potassium in interstitial cystitis and radiation cystitis

The urgency-frequency syndrome (UFS) (non-bacterial cystitis, interstitial cystitis) may well represent a heterogenous group with several etiologies. This study was based on the hypothesis that one subset of UFS patients has a leaky (to solutes) epithelium and cations such as potassium could thereby diffuse subepithelially and provoke symptoms. It was also hypothesized that normal impermeable transitional epithelium would not allow cations to diffuse across the cells during the K+ provocation test and no symptoms would be experienced. If the epithelium was permeable ("leaky"), diffusion would occur and provoke symptoms. Water or 0.4 M KCl was placed intravesically into normal volunteers and interstitial cystitis (IC) patients. Water did not provoke symptoms in either group but KCl provoked 4.5% of normals and 70% of IC patients. Differences were significant (P < 0.0001). This test provides a valuable diagnostic tool for UFS and a valuable research tool to separate epithelial permeability problems from other subsets of patients. A third group, consisting of 11 IC patients in remission on heparinoid therapy, was also tested and only 18% were provoked by KCl. Four patients with radiation cystitis were also examined and all four (100%) were provoked by the potassium.