Decreased nocturnal urinary antidiuretic hormone excretion in enuresis is increased by imipramine

Objective: To assess the role of integrated nocturnal antidiuretic hormone (ADH) secretion in children with enuresis, and possible modifications induced by treatment with imipramine. Patients and methods: The morning plasma ADH and nocturnal urinary ADH integrated concentrations were measured in 18 consecutive enuretic children (patients) and 21 age- and sex-matched controls admitted for minor treatment. Diurnal and nocturnal urine production, and plasma and urinary osmolality were also determined; lumbosacral radiography and uroflowmetry were undertaken in the patients. The assessments were repeated after 14 days of treatment with imipramine hydrochloride (orally, 20 mg/night). Results: Half the patients had occult spinal malformations but the uroflowmetry results were all within the normal range. The median (95% confidence interval, CI) urinary ADH integrated concentrations were markedly lower in patients, at 29.7 (22.1-37.3) vs 63.0 (35.1-90.8) pg/mL/h (P=0.03) than in controls. Plasma ADH levels were significantly increased by imipramine (0.64 to 1.47 pg/mL, 95% CI, 0.40-0.89 vs -0.26-3.2; P<0.001), as were nocturnal urinary ADH integrated concentrations, at 29.7 (22.1-37.3) vs 59.0 (37.3-80.6) pg/mL/h (P<0.001), and morning plasma osmolality decreased, from 298.5 (294.5-302.5) to 294.9 (292.4-297.3) mosmol/kg (P=0.003), as was the 24-h fluid intake, from 983 (721-1245) to 666 (435-897) mL (P=0.004). Conclusions: We conclude that enuretic children have a lower nocturnal ADH excretion; imipramine restores nocturnal ADH excretion, increases morning plasma ADH levels, and causes consistent changes in other biochemical variables.