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

Abstract

To assess the role of integrated nocturnal antidiuretic hormone (ADH) secretion in children with enuresis, and possible modifications induced by treatment with imipramine. 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). 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). 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.