URODYNAMIC RISK-FACTORS FOR RENAL DYSFUNCTION IN MEN WITH OBSTRUCTIVEAND NONOBSTRUCTIVE VOIDING DYSFUNCTION

Purpose: Urodynamic investigation of men with lower urinary tract symp toms, usually attributed to benign prostatic hyperplasia, often reveal s bladder outlet obstruction, detrusor instability and/or diminished v esical compliance. We investigated whether these urodynamic abnormalit ies alone or in combination contribute to renal dysfunction. Materials and Methods: A total of 161 men with lower urinary tract symptoms was evaluated by urodynamics, and outlet obstruction, detrusor instabilit y and decreased compliance (30 ml./cm. water or less) were noted. Seru m blood urea nitrogen (BUN) and creatinine were measured. Cases were c ategorized according to the urodynamic diagnosis. Mean values of serum BUN and creatinine as well as the incidence of elevated BUN and creat inine were compared among groups. Results: Of the cohort 54 men (34%) had elevated BUN and 19 (12%) had elevated serum creatinine. No signif icant correlation was found between the degree of obstruction and BUN or creatinine level. Mean serum BUN and creatinine, and the incidence of abnormal laboratory tests did not significantly differ among those with outlet obstruction, detrusor instability, both conditions or neit her condition. However in patients with outlet obstruction and detruso r instability there was a significantly increased incidence of azotemi a in the subgroup with diminished compliance (78%) versus the subgroup with normal compliance (36%). Conclusions: In men with voiding dysfun ction of a nonneurogenic etiology outlet obstruction with or without d etrusor instability does not appear to be a risk factor for elevated B UN and creatinine. However, when decreased bladder compliance is assoc iated with a combination of outlet obstruction and detrusor instabilit y, this risk is substantially increased.