Is urine methylhistamine a useful marker for interstitial cystitis?

Purpose: We determined whether urine methylhistamine (MH) is associated with other clinical features and bladder biopsy findings in interstitial cystitis (IC). Materials and Methods: Urine MH and University of Wisconsin symptom scores were measured before and 1 month after bladder distention for IC. Bladder biopsies were done at the time of distention. In new patients with IC who met cystoscopic criteria urine MH was compared before and after distention, and changes in urine MH were compared with changes in symptom scores. Predistention urine MH was tested for associations with the results of a symptom questionnaire, symptom response after distention, cystoscopic findings and bladder biopsy findings. Results: There were no significant associations between urine MH and symptom scores, response to bladder distention, cystoscopic findings or bladder biopsy features, including mast cell count by tryptase staining. Urine MH was similar in new patients with IC who did vs did not meet cystoscopic criteria. Urine MH was similar in new vs chronically treated patients with IC. Conclusions: Urine MH is unlikely to be useful as an objective marker of the response to bladder distention, as a method to predict which patients will respond to bladder distention or as a noninvasive substitute for bladder biopsy and mast cell counts by tryptase staining.