Search

Purpose: We investigated the role of increased solute excretion in children with desmopressin resistant nocturnal enuresis and nocturnal polyuria., Materials and Methods: A total of 42 children with monosymptomatic nocturnal enuresis and significant nocturnal polyuria with high nocturnal urinary osmolality (more than 850 mmol/l) were not responding to desmopressin. A 24-hour urinary concentration profile was obtained with measurement of urine volume, osmolality, osmotic excretion and creatinine. The control group consisted of 100 children without enuresis., Results: Based on osmotic excretion patients were classified into 3 groups. Group 1 had 24-hour increased osmotic excretion, most likely secondary to a high renal osmotic load. This was probably diet related since 11 of these 12 patients were obese. Group 2 had increased osmotic excretion in the evening and night, probably due to a high renal osmotic load caused by the diet characteristics of the evening meal. Group 3 had deficient osmotic excretion during the day, secondary to extremely low fluid intake to compensate for small bladder capacity., Conclusions: Nocturnal polyuria with high urinary osmolality in our patients with desmopressin resistant monosymptomatic nocturnal enuresis is related to abnormal increased osmotic excretion. This may be explained by their fluid and diet habits, eg daytime fluid restriction, and high protein and salt intake.

Purpose: We investigated the effect of imipramine on nocturnal urine output in patients with nocturnal enuresis., Materials and Methods: There were 15 monosymptomatic enuretic patients 15 to 37 years and 8 control subjects 25 to 32 years old. We measured nocturnal urine output, urine osmolality, creatinine clearance, osmolal clearance, free water clearance, excretion of solutes, fractional excretion of sodium, fractional excretion of potassium and plasma vasopressin with and without a single oral dose of imipramine (1 mg./kg. of body weight) taken at 8 p.m., Results: Baseline studies showed significantly larger and less concentrated nocturnal urine among enuretics compared with controls. We observed a marked antidiuretic effect of imipramine in 6 enuretics with severe nocturnal polyuria. The imipramine induced decrease in urine output was accompanied by reduced osmolal clearance. Approximately a third of the observed decrease in solute excretion was attributed to lower excretion of sodium and potassium. The remaining two-thirds were most likely caused by an increased tubular reabsorption of urea, which may be secondary to a sympathomimetic effect of imipramine tubules, possibly because of altered adrenal medullary function with an increase in proximal tubular sodium and water reabsorption. The resultant lower tubular flow rate facilitates tubular reabsorption of urea in the distal part of the nephron., Conclusions: Imipramine has a vasopressin independent antidiuretic effect if nocturnal polyuria is present. The antidiuretic effect of imipramine can be attributed primarily to increased alpha-adrenergic stimulation in the proximal tubules with a secondary increased urea and water reabsorption more distally in the nephron.

Purpose: We investigated the circadian variation in urine output, plasma angiotensin II, aldosterone, atrial natriuretic peptide, arginine vasopressin and blood pressure., Materials and Methods: We studied 17 elderly men with nocturia and lower urinary tract symptoms, and 10 age matched controls without nocturia., Results: Of the 17 patients studied 11 had a lack of diurnal variation in urine output and increased nocturnal urine production associated with increased nocturnal sodium excretion, and 6 had a diurnal variation in urine output comparable to controls., Conclusions: Nocturia in a large proportion of elderly men with lower urinary tract symptoms is caused by nocturnal polyuria and natriuresis.