FRIDAY, Dec. 1, 2006 (HealthDay News) -- An imbalance in a hormone-like substance called prostaglandin could explain tough-to-treat bed-wetting in some children, Danish researchers report.
Most children have their bed-wetting controlled by a medication called desmopressin, which reduces the amount of urine they produce at night. But about 30 percent of kids don't respond to the drug.
"Our understanding of bed-wetting is continuously improving, and we are getting better in helping children that suffer from the condition." said lead researcher Dr. Konstantinos Kamperis, from the University of Aarhus, Denmark. "How the body treats salt may play an important role in the etiology of the condition."
His team found that children with the type of bed-wetting that does not respond to desmopressin have more salt and urea in their nighttime urine, possibly caused by an imbalance of prostaglandin.
The report is published in the December issue of the American Journal of Physiology-Renal Physiology.
Bed-wetting is a common and bothersome problem. In fact, 5 million to 7 million children in the United States ages six and over wet their beds at night, according to the National Kidney Foundation.
In the study, researchers studied 46 seven-to-14-year-old children suffering from bed-wetting, all of who were treated as outpatients at Aarhus University Hospital. The youngsters had not responded to desmopressin. This group was compared to 15 children of similar age who had no bed-wetting problem.
The children spent two nights at the hospital. The first night was to acclimatize them to the hospital environment. During the second night, the researchers collected blood and urine from the children without waking them.
"We found that bed-wetters excrete larger amounts of salt at night, probably the reason for their bed-wetting," Kamperis said. "Apart from that, these children excrete larger amounts of prostaglandins, and this could explain both the large excretion of salt at night as well as the inability of desmopressin to treat this condition," he explained.
Compared with children who responded to desmopressin, the children who did not respond excreted twice as much urine during the night. In addition, the urine of children who wet their beds during the experiment contained more sodium, urea and prostaglandin than the other children, the researchers found.
"These findings point towards new treatment possibilities for bed-wetting with agents that reduce the amount of salt excreted in urine," Kamperis said. "Such studies are being conducted at the moment. Furthermore, we would be interested in researching the exact etiology of this excess nocturnal salt excretion. That could help our understanding of bed-wetting," he added.
One expert thinks that, while it is possible that prostaglandin might be involved in bed-wetting, the data from this study can't be used to change clinical practice right now.
"This study has some biological plausibility, because some studies suggest that prostaglandin inhibitors are useful in the treatment of bed-wetting," explained Dr. Joseph G. Barone, an associate professor of pediatrics and urology at Robert Wood Johnson Medical School, New Brunswick, N.J. "Prostaglandin inhibitors include Motrin and Advil, but, in my experience, these medications have not been effective against bed-wetting," he added.
Although bed-wetting is very common, there are few basic science studies on this condition, Barone said. "This study adds useful information to the medical literature, and it may lead to further studies. However, clinical recommendations cannot be made based on the results of this study," he said.
Barone noted that desmopressin is not a cure for the problem. "It works in about 50 percent of cases, in my experience," he said. "When desmopressin works, it is not a cure, just a Band-Aid. The theory is that desmopressin reduces the amount of urine at night, and the child does not, therefore, wet the bed."
Bed-wetting continues to be a multifaceted condition that is commonly associated with developmental immaturity, Barone said. "The most compelling evidence that bed-wetting is developmental in nature is the child's natural tendency to outgrow the problem in 99 percent of cases," he said.
There's more on bed-wetting at the National Kidney Foundation.