DAYTIME FUNCTIONAL BLADDER CAPACITY AS A PREDICTOR OF RESPONSE TO DESMOPRESSIN IN MONOSYMPTOMATIC NOCTURNAL ENURESIS

Objective: The objective of this study was to identify a cost-effectiv e method of predicting a therapeutic response to desmopressin (DDAVP) by correlating daytime functional bladder capacity, age and urine osmo lalities in patients with monosymptomatic nocturnal enuresis. Material s and Methods: Thirty-five children out of 51 who initially presented to our institutions were included in the study. The remainder was excl uded for lack of complete data. Constipation was actively addressed an d was managed by administration of evening enemas for 3 consecutive da ys and dietary adjustment prior to initiating the study. Each micturit ion as measured throughout the day and the maximal daytime functional bladder capacity was determined as the largest void over a 2-day perio d. Urine samples were collected at home at 08,00, 16:00 and 22:00 (tim es that would best reflect the fluctuations in plasma vasopressin leve ls). Intranasal DDAVP was then administered, titrating the dose over a a-week period. The initial dose was 10 mu g and the dose was increase d 10 mu g every 3 days. Results: The response to DDAVP was then evalua ted and of the 35 children, 27 demonstrated a complete response to DDA VP tall at doses between 10 and 30 mu g), These were then related to t he possible predictive factors. There was a significant correlation be tween a high maximum daytime functional bladder capacity and response to DDAVP (p = 0.006), Similarly, age was also predictive of a good res ponse to DDAVP treatment (p = 0.008). However, spot urine osmolalities were not predictive of a response to DDAVP (p > 0.1). Conclusions: Fu nctional bladder capacity is a reliable predictor of response to desmo pressin; children with larger capacities are more likely to exhibit a successful response, Older children have a better response rate than y ounger ones. Spot urine osmolality measured on specimens collected in the home setting is not predictive of response to desmopressin.