No, the Potassium Sensitivity Test Should Not Be Performed
The American Urological Association explicitly states that the potassium sensitivity test (PST) lacks both the specificity and sensitivity to change clinical decision-making and is not recommended for diagnosing interstitial cystitis/bladder pain syndrome (IC/BPS). 1, 2
Why the PST Is Not Indicated
The guideline evidence is unequivocal on this point:
- The PST has poor diagnostic characteristics with a sensitivity of only 69.5% and specificity of 50%, meaning it cannot reliably rule in or rule out IC/BPS 3
- A positive test adds no useful clinical information: even when positive, only 66% of patients actually have IC/BPS, which is barely better than the pre-test probability of 56% in symptomatic populations 3
- A negative test is equally unhelpful: nearly half (46%) of patients with negative PST results still have IC/BPS, making it useless for excluding the diagnosis 3
- The test can be painful for patients with persistent symptoms and offers no additional diagnostic value 4
What You Should Do Instead
The diagnosis of IC/BPS is clinical and does not require the PST. 1, 2 Here's the appropriate diagnostic approach:
Essential Clinical Criteria
- Document that symptoms (bladder/pelvic pain, pressure, or discomfort with urinary frequency, nocturia, and urgency) have been present for at least 6 weeks 1, 2
- Confirm negative urine cultures to exclude infection 1, 2
- Note that excruciating pain upon catheterization is consistent with IC/BPS but is not diagnostic by itself 1
Required Laboratory Testing
- Urinalysis and urine culture are mandatory 1, 2
- Urine cytology if the patient has smoking history or unexplained hematuria (to exclude bladder cancer) 1, 2
Baseline Symptom Documentation
- Use validated tools: Genitourinary Pain Index (GUPI), Interstitial Cystitis Symptom Index (ICSI), or Visual Analog Scale (VAS) 1, 2
- Obtain a one-day voiding log at minimum to document frequency and voided volumes 1, 2
When to Consider Cystoscopy
Cystoscopy is not necessary for uncomplicated presentations but should be performed when: 1, 2
- Hunner lesions are suspected (these patients respond well to specific treatment and benefit from early diagnosis) 1, 2
- The diagnosis is uncertain 1
- You need to exclude bladder cancer, stones, or foreign bodies 1, 2
Important Clinical Pitfall
The PST was historically used and some older literature suggests it might predict treatment response 4, 5, 6, 7, but current AUA guidelines supersede this older research and explicitly recommend against its use 1, 2. The test's poor performance characteristics and potential to cause additional pain without providing actionable information make it inappropriate for clinical practice.
Bottom line: Make the diagnosis based on clinical criteria (pain/pressure related to the bladder with urinary frequency for ≥6 weeks, negative cultures, exclusion of other pathology), not the PST. 1, 2