Nocturnal Enuresis (Bedwetting)
Involuntary urination during sleep, affecting children and some adults. Desmopressin is an approved treatment that reduces overnight urine production by mimicking vasopressin's antidiuretic effect (V2 receptor activation), available as nasal spray and oral formulations.
Technical Context
Primary nocturnal enuresis (PNE): never achieved sustained dryness. Pathophysiology: multifactorial — nocturnal polyuria (reduced nocturnal vasopressin secretion → failure to concentrate urine during sleep), detrusor overactivity (uninhibited bladder contractions), and high arousal threshold (failure to wake in response to full bladder). Desmopressin mechanism: V2 receptor activation → AQP2 insertion → water reabsorption → reduced urine volume. Available forms: oral tablet (200-400μg at bedtime), oral lyophilisate/melt (120-240μg, sublingual — preferred for children due to easier administration and more consistent absorption), and nasal spray (10-40μg — less commonly used due to variable absorption and hyponatraemia risk in children). Response: approximately 60-70% show significant response. Key safety: fluid restriction in the evening (maximum 200mL from 1 hour before to 8 hours after desmopressin) is essential to prevent dilutional hyponatraemia, which can cause seizures. Desmopressin efficacy is assessed after 1-2 weeks; treatment duration is typically 3-6 months with periodic withdrawal trials.