Purpose: The anti-incontinence effect of desmopressin resides in its concentrating capacity and antidiuretic properties. We compared nighttime urine production on wet and dry nights in a highly selected study population of children with monosymptomatic nocturnal enuresis associated with proved nocturnal polyuria who responded only partially to intranasal desmopressin.
Materials and methods: We retrospectively analyzed 39 home recordings of nocturnal urine production and maximum voided volume in children 7 to 19 years old (median 8.9) with monosymptomatic nocturnal enuresis with nocturnal polyuria who had a partial response to desmopressin. Nocturnal diuresis volume and maximum voided volume were documented at baseline (14 days) and during 3 months of followup.
Results: Baseline nocturnal urine output (439 +/- 39 ml) was significantly higher than the maximum voided volume (346 +/- 93 ml, p <0.01). During desmopressin treatment nocturnal urine output on wet nights (405 +/- 113 ml) differed significantly from that on dry nights (241 +/- 45 ml). During treatment nocturnal urine output on wet nights did not differ from baseline values.
Conclusions: Persistence of nocturnal polyuria on wet nights in partial desmopressin responders may be related to an insufficient antidiuretic effect. In addition to poor compliance and suboptimal dosing, the poor bioavailability of intranasal desmopressin may be a pathogenic factor. Further prospective studies are needed.