The potassium sensitivity test (PST) causes bladder discomfort after instillation of a 0.2 molar potassium chloride solution (0.2 M KCl).

The potassium sensitivity test (PST) causes bladder discomfort after instillation of a 0.2 molar potassium chloride solution (0.2 M KCl). The objective of the present study was to assess maximum bladder capacity (Cmax) using a 0.2 M KCl solution compared with 0.9% sodium chloride (NaCl) in patients with IC, in order to achieve diagnosis.

The authors studied 17 female patients diagnosed with IC, based on criteria from the National Institute of Diabetes and Digestive and Kidney Diseases. Patients completed the Pelvic Pain and Urgency/Frequency (PUF) questionnaire. Cystometry was performed first with a 0.9% NaCl solution, followed by 0.2M KCl soon after. The desire to void and Cmax were measured in both cystometries. After undergoing tests with each solution, the patients evaluated pain and urgency by using a visual numeric scale.

All patients presented a larger decrease in Cmax when using KCl, compared with NaCl. The median Cmax decrease was 32.8% (range, 7.69% - 57.8%). A decrease in Cmax > 30% was observed in 9 patients; the remaining 8 patients had a decrease < 30%. All patients reported greater discomfort with the use of 0.2M KCl solution. The visual numeric scale score for pain revealed a mean value of 2.41 for the NaCl solution and 4.52 for KCl, with 5 representing maximum pain. The average PUF score was 23.76 (range, 18-33). When the PUF score was compared between patients with a decrease in Cmax > 30% and < 30%, no statistically significant difference was found.

PST is a well-tolerated alternative when evaluating both the increased sensitivity to potassium and the diagnosis of IC, considering the reduction in Cmax. The PUF score has no direct correlation with the PST positivity.

Written by:
da Silveira AB, Riccetto CLZ, Natalin RA, Herrmann V, Dambros M, Palma P.   Are you the author?

Reference:
UroToday Int J. 2009 Aug;2(4).
doi:10.3834/uij.1944-5784.2009.08.08

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