Intravesical potassium chloride sensitivity test in men with chronic pelvic pain syndrome

Intravesical potassium chloride has been reported to cause pain in patients with interstitial cystitis and male chronic prostatitis (CP)/chronic pelvic pain syndrome (CPPS). We performed the potassium chloride sensitivity test (PST) in subjects with CP/CPPS and healthy men without pelvic pain.

We recruited 40 men with CP/CPPS and 63 healthy men. The National Institutes of Health CPPS symptom index was used to measure the severity of symptoms. We instilled 100 ml physiological saline (NaCl 0.9%) intravesically. The bladder was emptied and 100 ml potassium chloride solution (KCl 40 mEq) were instilled. The subjects were asked to score urgency (0 to 10) and pain (0 to 10) sensations after each instillation. A positive PST was defined by 5 different cut-off points as the difference in score between KCl and NaCl instillations. Logistic regression analyses and area under the receiver operating characteristics curve were used to determine the predictive power of PST in CP/CPPS.

There was no difference in pain and urgency scores between the men with CP/CPPS and controls (p >0.05 for each). Men with CP/CPPS had higher pain and urgency scores with KCl than with NaCl (p = 0.011 and 0.033, respectively). The rates of positive PST were 50% and 36.5% in the CP/CPPS and control groups, respectively (p = 0.160). There was no significant correlation of potassium chloride sensitivity scores with National Institutes of Health symptom scores (p >0.05 for each). The sensitivity, specificity, and positive predictive and negative predictive values of PST were 50%, 63.5%, 46.5% and 66.7%, respectively.

Although there was a significant increase in pain and urgency scores following KCl instillation in patients with CP/CPPS, these scores and the rate of positive PST were not statistically different from those of healthy subjects. Thus, PST does not have a good predictive value in the diagnosis of CP/CPPS.