Objective: The aim of this group of studies was to determine the relationship between primary nocturnal enuresis and arginine-vasopressin (AVP) secretion.
Methods: The first study compared the 24-hour AVP secretion profiles of an enuretic group and a control group. Blood samples were collected every hour. In the second study, we compared nocturnal AVP secretion in group A, with low urinary osmotic pressure (UOP) and large nocturnal urinary volume (NUV), with that of group D, with normal UOP and small NUV. The plasma AVP level was measured at 30-min sampling intervals. In the third study, the change in nocturnal AVP secretion from before to after treatment was determined.
Results: The plasma AVP level was significantly lower in the enuretic group from 23:00 through 04:00 h. The mean plasma AVP level was significantly lower in group A than in group D at all points of measurement. The mean nocturnal AVP level in group A (0.64 +/- 0.23 pg/ml) was lower than that in group D (1.43 +/- 0.72 pg/ml) (p < 0.0001). The mean nocturnal AVP level after treatment was significantly increased, from 0.47 pg/ml before treatment to 0.78 pg/ml after treatment (p = 0.01). However, a significant increase was noted in only 10 cases.
Conclusions: These findings suggest that decreased nocturnal AVP secretion is one of the causes of bed-wetting. However, the improvement of bed-wetting was not solely due to the increased nocturnal AVP secretion.