Hypothesis/aims of study. Urine incontinence seems to include several pathogenetic forms, as efficient therapy is provided by different medications. Commonly used in the treatment of female patients with overactive bladder and nocturnal polyuria is desmopressin which normalizes the water excretion of the kidney, which is disturbed by a presumed inverted rhythm of vasopressin secretion in these patients. The current analysis was undertaken to evaluate the clinical efficiency of desmopressine in incontinent patients with nocturnal polyuria and polyuria.
Study design, materials and methods. A total of 84 patients with complaints of urinary incontinence, polyuria (24-urine volume of 40 mL/kg bodyweight or above) or nocturnal polyuria (nocturnal volume/24-h urine volume of 0.33 or above) and 14 control subjects were included. Mean patient age was 43.6 ± 4.6 years, in control subjects 38.5 ± 6.4 (p > 0.05). All participants performed 24h-urinecollection to determine the voided volumes and the levels of creatinine, osmolality, sodium, magnesium and potassium for each sample. A blood sample was taken during the 24-urinecollection to determine the levels of creatinine, osmolality, sodium, magnesium and potassium. The examination of patients with polyuria and nocturnal polyuria was performed twice: in the initial state and one month after the start of treatment with optimal dose of desmopressin. Optimal dose was established through an open-label dose-titration using 0.1 mg, 0.2 mg and 0.4 mg of desmopressin (Minirin). Safety parameters assessed included incidence of adverse events, vital signs and serum sodium levels.
Results. In patients with polyuria and nocturnal polyuria the glomerular filtration rate was normal, whereas diuresis and solute (sodium, magnesium, potassium) excretion in night samples in nocturnal polyuria and both in night and day samples in polyuria were increased. The higher diuresis and the higher solute excretion observed in nocturnal polyuria and polyuria are accompanied by an increase of free water reabsorption. In nocturnal polyuria and polyuria a high correlation was found between the free water reabsorption and solute excretion. This occurs against the background of the high night and day osmotic concentration. The statistically significant recovery of renal function occurred in 12 incontinent women with polyuria and 18 with nocturnal polyuria. In these papients there was a statistically significant decrease in diuresis, osmolar clearance and excretion of sodium, potassium and magnesium.
Concluding message. As desmopressin affects cells of the thick ascending limb of Henle’s loop, it is likely that nocturnal polyuria and polyuria result from a disturbed regulation of the function of these cells. Normalization can be achieved by desmopressin administration to stimulate V2-receptors, which increase water permeability and water reabsoption in collecting ducts as well as ion reabsorption by cells of the thick ascending limb of Henle’s loop.