Short-term effects of desmopressin on water and electrolyte excretion in adults with nocturnal polyuria

Purpose: Increased calcium excretion due to desmopressin has been reported in children with nocturnal enuresis. Desmopressin is often used to treat adult patients with nocturnal polyuria. However, data on the effect of desmopressin on water/electrolyte excretion in adults are scarce. We present the short-term effects of desmopressin on water and electrolyte excretion in adult patients with nocturnal polyuria. Materials and Methods: A total of 16 male patients with nocturnal polyuria, mean age 76.3 years, received 0.1 or 0.2 mg desmopressin before sleep. Frequency volume chart was recorded, and daytime and nighttime urine samples were collected separately before and after desmopressin administration. Urinary excretions of sodium, potassium and calcium were determined, and compared before and after treatment with desmopressin. Results: Desmopressin significantly increased urine osmolality, decreased nocturnal total urine volume, reduced the ratio of nocturnal urine volume-to-whole day urine volume and decreased nocturnal voiding frequency. Nocturnal urinary excretion of calcium (mean 0.137 vs 0.169 mg/kg body weight per hour, p = 0.004) and whole day excretion of calcium (mean 165.9 vs 200.0 mg per day, p = 0.012) were increased after desmopressin treatment. Nocturnal urinary potassium excretion (mean 0.030 vs 0.025 mEq/kg body weight per hour, p = 0.030) and whole day potassium excretion (mean 40.7 vs 36.1 mEq per day, p = 0.017) were decreased by desmopressin treatment. However, desmopressin treatment did not significantly change urinary secretion of sodium and chloride at nighttime or for the whole day. Conclusions: Desmopressin reduces nocturnal urine volume and nocturnal voiding frequency in male patients with nocturnal polyuria. However, increased calcium and decreased potassium excretion following desmopressin treatment deserve attention particularly when it is used on a long-term basis.