Desmopressin for nocturnal enuresis: urinary osmolality and response

To measure the effect of intranasal desmopressin (l-deamino 8-D-arginine vasopressin, DDAVP) on urine osmolality in a group of patients with persistent primary enuresis, and to determine whether changes in osmolality can the predict response to treatment.

Thirty-seven patients with persistent primary nocturnal enuresis were entered into a double-blind placebo-controlled crossover trial of 20 micrograms intranasal DDAVP spray. Morning urinary osmolality was measured on two occasions during each phase of treatment and the clinical response recorded in a diary.

Thirty-one patients (22 males and nine females) were evaluable at the end of the trial period. A good clinical response, defined as enuresis on two nights or fewer each week, occurred in 12 of 31 (39%) patients, but complete continence was attained in only two. The response was better in older patients and in those with less frequent enuresis. The mean and peak urinary osmolality of the morning urine samples were higher while on treatment with DDAVP compared with placebo, but this difference was not statistically significant and the response did not predict a good clinical outcome in improving the enuresis.

Treatment with DDAVP can produce a socially acceptable level of dryness in some patients with refractory nocturnal enuresis. However, the early morning urinary osmolality, as a reflection of changes in nocturnal osmolality, was not useful in distinguishing this group or in selecting those who will respond to treatment.