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You are here:Home Patient Information Treatment OptionsFact SheetsIC and the Potassium Chloride Sensitivity Test
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Many IC patients have expressed their concerns regarding the usefulness of the potassium chloride sensitivity test (also known as the KCl Test or Parsons Test), in diagnosing and treating IC. The ICA has also received comments from patients regarding the pain induced by the test. More and more patients report that their physicians are relying on this test to diagnose IC and to predict their response to medications. However, careful investigation and consideration of all available information regarding the KCl Test must be taken into account before accepting the validity of the test. This test has yet to be proven or accepted as a diagnostic or predictive IC test.
The test consists of instilling a solution of potassium chloride, known chemically as KCl, into the bladder via urinary catheter. It has been suggested for two uses: 1) a diagnostic test for IC; 2) a predictive test for response to IC-specific medications such as Elmiron and other heparinoids that are thought to work by coating the bladder lining.
The KCl Test was originally designed as a possible diagnostic test for IC.[1] Yet, based on current available data, this test lacks accuracy. One study found the KCl Test to be 75 percent accurate, i.e. if 100 IC patients are given this test, only 75 of these patients will be diagnosed accurately. Another study found the test to be only 60 percent accurate in the diagnosis of IC.[2] More recently published data suggest that the KCl Test should not be considered as a reliable tool for the diagnosis of IC.[3] These researchers propose that clinical findings (urinary urgency, frequency, and/or pain in the absence of other urological conditions), along with cystoscopy/ hydrodistention, are still the most consistently accurate and reliable means of diagnosing IC.[4]
The test is thought to be able to gauge the permeability of the glycosaminoglycans (GAG) 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, intravesical heparin, etc. [5,6] However, its usefulness as a predictor of response to heparinoids has not been substantiated.[7]
During the test, patients are asked to report the degree of severity of pain/urgency that they experience while the KCl solution is in the bladder. This pain response may be present not only during, but after the test, and can last as long as days or 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 is essential that an analgesic “rescue” solution such as Marcaine and heparin be instilled into the bladder immediately after the KCl Test, so that the potential for a painful flare-up is reduced. Some patients have required opioid analgesics to ease the pain after this procedure.
Of primary concern is that if the test results are negative, urologists may mistakenly tell their patients that they do not have IC. Also, because of the test's considerable publicity, it is possible that the KCl Test could be accepted by many urologists and other physicians as a reliable substitution for cystoscopy with hydrodistention under general or regional anesthesia, which is still considered by many to be the "gold standard" for diagnosis of IC.
The KCl Test is also 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. Furthermore, the test may be negative, even if a patient has IC, if the patient: 1) has recently received DMSO or heparin intravesical instillations; 2) has recently undergone hydrodistention; 3) has been taking Elmiron; and/or 4) does not exhibit bladder permeability as a part of their IC.
If the above conditions have been ruled out, and the patient has symptoms consistent with IC, then the patient could be treated empirically, rather than be subjected to this painful test.
There are less painful, less invasive, and more accurate diagnostic tests currently under investigation that will hopefully lead to a commercially available test in the future.
There are less painful, less invasive, and more accurate diagnostic tests currently under investigation that will hopefully lead to a commercially available test in the future.
- The lidocaine challenge[8] was developed by Robert Moldwin, MD. It is a therapeutic technique that may be useful for diagnosis, helping to differentiate between bladder and nonbladder sources of pain. The process involves instillation of lidocaine, with a variable combination of heparin, gentamicin, triamcinolone, or other agents. Patients are instructed to keep this mixture in the bladder for 30 minutes if possible before voiding. For therapeutic purposes, it can be repeated on a weekly basis for 8 to 12 weeks and then at increasing intervals. It can also be self-administered at times of symptom exacerbation. Pain relief may last for days.
- Researchers have identified two factors that may explain changes in the bladder of IC patients. The first factor is a heparin-binding epidermal growth factor (HB-EGF), important for cell growth and healing. This factor is significantly decreased in the urine of IC patients when compared with specimens from healthy people or patients with other urologic conditions, such as urinary tract infections. The second factor is a protein known as an antiproliferative factor (APF) which has been isolated in IC patient urine specimens. This protein may prevent the growth of new, healthy bladder lining cells. These research findings could lead to a diagnostic test for IC as well as a new treatment.[9, 10, 11, 12]
- Also, a lactulose/rhamnose test, similar to the test used to diagnose gastrointestinal permeability, is being investigated.13 This test for bladder permeability involves instilling a sugar solution into the bladder and subsequently checking for levels of this sugar molecule in the blood. This new permeability test may distinguish intact versus permeable bladders, and is far less traumatic to the patient when compared to the potassium test.
The KCl Sensitivity Test is a painful test to administer to patients, many of whom present initially with significant pain. Because it is inaccurate 40 percent of the time, many IC patients may go undiagnosed due to misunderstanding on the urologist's part. In addition, its usefulness as a predictor of response to heparinoids has not been substantiated. Until more data become available, the true purpose of the KCl sensitivity test in relation to IC remains questionable.
Until an equally accurate, less invasive and pain-free test becomes available, the ICA advocates that the diagnosis of IC be based on clinical findings in the absence of other identifiable causes, and cystoscopy with hydrodistention under regional or general anesthesia, as deemed necessary by the treating physician.
- [1] Parsons CL, Greenburger M, Gabal L, Bidair M, Barme G (1998). The Role of Urinary Potassium in the Pathogenesis and Diagnosis of Interstitial Cystitis. The Journal of Urology, 159(6), 1862-1867.
- [2] Teichman JMH, Nielsen-Omeis BJ, (1999). Potassium Leak Test Predicts Outcome in Interstitial Cystitis. The Journal of Urology, 161(6), 1791-1796.
- [3] Chen T Y-H, Begin LR, Corcos J. Assessment of Potassium Chloride Test in Comparison with Symptomatology, Cystoscopic Findings and Bladder Biopsy in the Diagnosis of Interstitial Cystitis. AUA Annual Meeting, Anaheim, CA. 2001.
- [4] Chambers GK, Fenster HN, Cripps S, Jens M, and Taylor D. (1999). An Assessment of the use of Intravesical Potassium in the Diagnosis of Interstitial Cystitis. The Journal of Urology, 162(3), 699-701.
- [5] Teichman, et al.
- [6] Parsons, et al
- [7] Liandier F, Gregoire M, Naud A, Bedard G, Lacombe L. Profile of Interstitial Cystitis Patients: A Review of 189 Cases at L’Hotel-Dieu de Quebec. AUA Annual Meeting, Anaheim, CA. 2001.
- [8] Moldwin RM, Sant GR. Interstitial cystitis: a pathophysiology and treatment update. Clin Obstet Gynecol. 2002;45:259-72.
- [9] Keay S, Kleinberg M, Zhang CO, Hise MK, Warren JW. Bladder epithelial cells from patients with interstitial cystitis produce an inhibitor of heparin-binding epidermal growth factor-like growth factor production. J Urol Dec;164(6): 2112-8, 2000.
- [10] Keay S, Warren JW, Zhang CO, Tu LM, Gordon DA, Whitmore KE. Antiproliferative activity is present in bladder but not renal pelvic urine from interstitial cystitis patients. J Urol Oct;162(4):1487-9, 1999.
- [11] Keay S, Warren JW. A hypothesis for the etiology of interstitial cystitis based upon inhibition of bladder epithelial repair. Med Hypotheses Jul;51(1): 79-83, 1998.
- [12] Keay S, Zhang CO, Hise MK, Hebel JR, Jacobs SC, Gordon D, Whitmore K, Bodison S, Gordon N, Warren JW. A diagnostic in vitro urine assay for interstitial cystitis. Urology Dec;52(6): 974- 8, 1998.
- [13] Erickson DR, Herb N, Ordille S, Harmon N, Bhavanandan VP. A new direct test of bladder permeability. J Urol Aug;164(2): 419- 22, 2000.
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