Intravesical potassium sensitivity in patients with interstitial cystitis and urethral syndrome

Objectives. To examine populations with diagnosed clinical interstitial cys titis (IC) and urethral syndrome and normal controls using the potassium se nsitivity test (PST), to determine the incidence of PST-provoked pain and/o r urgency, and to document the type and location of IC and urethral syndrom e pain, association of pain with sexual intercourse, and family history of female urgency/frequency problems. Methods, The PST and a questionnaire were administered to 466 patients with clinical IC, 116 patients with urethral syndrome, and 42 controls. Results. The PST was positive in 78% of patients with clinical IC, in 55% o f patients with urethral syndrome, and in 0% of the controls. Of the patien ts with clinical IC, 9% responded to the PST with pain only and 8% with urg ency only. Patients with clinical IC reported the pain as dysuria (58%), ur ethral/vaginal (76%), above the pubic bone (53%), lower abdomen (47%), lowe r back (35%), vaginal (51%), and inguinal (28%). The results were similar f or patients with urethral syndrome. Of the sexually active men and women, 7 1% with clinical IC and 59% with urethral syndrome reported pain associated with intercourse. Urgency/frequency problems in female relatives were repo rted by 35% of patients with IC and 33% of those with urethral syndrome. Conclusions. The significant potassium sensitivity in both patients with cl inical IC and those with urethral syndrome and the absence of potassium sen sitivity in normal controls indicates that a positive PST suggests the pres ence of an abnormal bladder epithelium. The lower rate of positive PSTs in patients with urethral syndrome reflects the less severe, more intermittent , nature of the symptoms in urethral syndrome (early IC). Pelvic pain of bl adder origin may occur anywhere in the pelvis. Finally, IC appears to have a genetic component. UROLOGY 57: 428-433, 2001. (C) 2001, Elsevier Science Inc.