Decreased urinary uronic acid levels in individuals with interstitial cystitis

The pathogenesis of interstitial cystitis currently is unknown. A possible etiology is that the transitional epithelium is defective, leading to molecular leaks that initiate the disease complex. An important surface defense mechanism is the glycosaminoglycans or polysaccharides that line the bladder epithelium and act as a nonspecific antiadherence factor blocking access of bacteria, microcrystals, proteins and ions to the underlying transitional cells. We examined the excretion of urinary macromolecular uronic acid and glycosaminoglycans in normal individuals and those with interstitial cystitis. A total of 37 controls had a mean macromolecular uronic acid level of 56 nmol. per mg. creatinine, compared to 40.2 nmol. per mg. creatinine in 43 patients with active disease (differences were significant, p equals 0.03). The median excretions of glycosaminoglycan uronate for controls and patients were 15.1 and 11.1 nmol. per mg. creatinine, respectively. (There was an over-all tendency to decrease excretion in patients with a p value of 0.06.) Specimens obtained at cystoscopy from patients with active interstitial cystitis had ureteral macromolecular uronic acid levels of 40.5 nmol. uronate per mg. creatinine compared to 43.6 nmol. uronate per mg. creatinine from the bladder. Interstitial cystitis patients had 16.0 nmol. glycosaminoglycan uronate per mg. creatinine compared to 14.6 nmol. per mg. creatinine in normal controls. Neither of these differences was statistically significant. It would appear that there is a tendency to lower macromolecular uronic acid and polysaccharide excretion in individuals afflicted with this syndrome.