What is the primary function of DDAVP in treating enuresis?

DDAVP, also known as desmopressin, functions primarily as an antidiuretic hormone (ADH) analog. Its main role in treating enuresis, particularly nocturnal enuresis (bedwetting), is to reduce urine production at night by enhancing water reabsorption in the kidneys. This mimics the effect of naturally occurring vasopressin, which helps to concentrate urine and decrease urine volume, thereby alleviating the frequency of nighttime urination.

By acting as an antidiuretic, DDAVP effectively addresses the underlying issue in many cases of enuresis, which is the overproduction of urine during nighttime sleep. This allows children to remain dry throughout the night, significantly improving their quality of life and reducing the psychological impacts associated with bedwetting.

The other options do not accurately represent the primary mechanism of DDAVP. It does not increase urine production nor act as a diuretic, which would instead increase urine output. Also, it does not relax bladder muscles; its primary effect is related to urine concentration rather than bladder muscle function. Therefore, the key differentiation of DDAVP's action as an antidiuretic hormone is crucial in understanding its therapeutic use in enuresis.