BERKELEY, CA (UroToday Inc.) - Interstitial cystitis (IC) is a chronic inflammatory disease of the bladder. It occurs predominantly in women and is a heterogeneous syndrome divided into 2 subtypes, the classic form and non-ulcer form. The differences between the 2 subtypes include clinical presentation and age distribution, but they also present with different histopathological and neurobiological features. Dr. Logadottir and colleagues evaluated the expression of nitric oxide as a means to discriminate between the two forms, and they report their findings in the March, 2004 issue of the Journal of Urology.

Nitric oxide is a gaseous free radical synthesized from L-arginine by a family of isoenzymes, nitric oxide synthases. Nitric oxide is a biological mediator and cell-signaling molecule that has various pathophysiological roles, which include mediating smooth muscle relaxation, neurotransmission and vasodilation. Nitric oxide is proposed to play a role in micturation, and regulation of urinary nitric oxide synthase activity is potentially important in immunological response in IC.

In this study the luminal formation of nitric oxide in the bladder in patients with classic and non-ulcer IC, as well as in controls was measured and correlated with established criteria for diagnosis and subtyping.

17 patients with IC diagnosed according to the National Institute for Diabetes and Digestive and Kidney Diseases criteria were further subclassifed by endoscopic and histopathological criteria. 10 patients had classic IC and 7 patients had non-ulcer type IC. 3 of 10 patients with classic IC had disease in remission and were without symptoms. Control patients had other urological complaints including overactive bladder, but excluding infections and malignancy. An air sample from the urinary bladder and a control sample of air surrounding the patient were measured. A catheter was inserted, urine collected for culture and air introduced into an empty bladder. After 5 minutes of incubation the air was aspirated into a syringe and immediately examined in a chemiluminescence nitric oxide analyzer. A control sample of air surrounding the patient was measured as well. The detection level for nitric oxide was 1.5 ppb, and there was no interference from other nitrogen oxides.

All patients with classic IC showed high or very high levels of nitric oxide. Neither non-ulcer type IC or controls had any significant increase in nitric oxide in the bladder. The increased nitric oxide level in classic IC patients was not related to symptoms or various prior treatments such as transurethral resection or intravesical dimethyl sulfoxide instillations.

Accurate subtype diagnosis in IC patients influences their treatment selection. The ability to classify the classic or non-ulcer subtypes by the proposed technique would potentially avert, for example, the need for hydrodistension under anesthesia.

The 17 patients enrolled in this study were retrospectively selected from a group of 250 patients. As such, a prospective randomized trial in a larger number of patients may support this new methodology.

J Urol 2004;171:1148-1151.