The Potassium Chloride Sensitivity test consists of instilling 2 sterile solutions of sodium chloride and potassium chloride, known chemically as KCl, into the bladder via a urethral catheter which your nurse or consultant will insert. The test can take up to 30-40 minutes.  It has been suggested for two uses:

• Diagnostic test for Interstitial Cystitis (IC). This Test can be useful in diagnosing or ruling out IC because patients with IC are believed to have bladders with a damaged lining.  As the natural potassium in the urine passes through the kidneys and into the bladder, the potassium seeps into the damaged bladder lining causing symptoms of urinary urgency, frequency, pain and discomfort.  A Potassium test can therefore help determine if in fact potassium is causing the symptoms.  A Cystoscopy (a scope which looks into the bladder) may also be necessary.
• Predictive test for response to IC-specific medications such as pentosan polysulfate sodium (Elmiron), Cystistat and other heparinoids that are thought to work by coating the bladder lining.

The KCl Sensitivity Test was originally designed as a possible diagnostic test for Interstitial Cystitis. However, there are questions about the accuracy of this test. One study found the KCl sensitivity test to be 75 percent accurate, which means that if 100 IC patients are given this test, only 75 of these patients will be diagnosed accurately. Another study found the test to be 60 percent accurate in the diagnosis of IC. 

The KCl Sensitivity Test is being evaluated as a predictive test. The test is thought to be able to gauge the permeability of the glycosaminoglycans (GAG) or protective layer of the bladder, which may be defective in some IC patients. Some investigators believe that IC patients who respond positively to the test will be more likely to be helped by a specific class of IC treatments, the mucosal surface protectants (or heparinoids), such as oral Elmiron or Cystistat.  

During the test, patients are asked to report the degree of severity of pain and urgency that they may experience while the KCl solution is in the bladder. This pain response may be present not only during, but after the test, and can sometimes last as long as days to weeks following the procedure. And, it may be difficult for patients to accurately quantify an increase in pain when they may already be in considerable pain prior to administration of the test. It has been suggested that a sodium chloride flush and local anesthetic gel such as Instilla gel be instilled into the bladder immediately after the KCl Sensitivity Test, so that the potential for a painful flare-up is reduced. 

The KCl Sensitivity Test is not specific for IC. Patients with acute urinary tract infection, radiation cystitis, other inflammatory conditions of the bladder, and those receiving chemotherapy for bladder cancer may also have a positive response to the test. Also, the test may be negative, even if a patient has IC, if the patient:

• Has recently received Cystistat, DMSO, Gepan or heparin intravesical instillations.
• Has recently undergone hydrodistention.
• Has been taking Elmiron.
• Does not exhibit bladder permeability as a part of their IC. 

If you have any concerns or questions about this test please contact:

Michelle O’Brien,
Urology nurse,
The Galway Clinic.
091 785771
OR

Your Consultant Urologist.