A couple of weeks ago, I saw a 5-year-old girl who was still wetting the bed every night. It’s a common complaint: at least 15 percent of healthy 5-year-olds are not reliably “dry” at night. And bed-wetting is quite common even in older children.  But what may be most surprising about primary nocturnal enuresis, to use the clinical term for urinary incontinence in a child who does fine by day but has never been reliably dry through the night, is that it is often genetically based.  In other words, it is not about emotional problems, or mistakes a parent made during potty training, or laziness, which some still attribute to the bed-wetter himself. (The problem is about three times as common in boys as in girls.)  Indeed, one of the worst things about bed-wetting is the stigma. Sufferers and their families have been accused of everything from poor parenting to latent criminality. (In 1945, The New York Times reported on a psychological study of the backgrounds of 500 men who got into disciplinary trouble in the wartime Navy. The most powerful predictor of failure in the Navy, the article reported, was a combination of three factors: expulsion from school, civilian arrest and enuresis beyond age 5.)  Enuresis can have a number of physiological causes. Some children lack a hormone that decreases urine production at night. Others wet the bed simply because their bladder capacity is small.  “Here’s the encounter I usually have when I see children in my clinic,” Dr. Jennifer Abidari, chief of pediatric urology at the Santa Clara Valley Medical Center in California, told me. “I draw a bunch of bladders, and three of them are big and one of them is very small.  “I ask them which one was wetting and they’ll usually guess the smaller one, and I’ll say, ‘You’re right  you have a bladder that’s smaller than your age, and it’s not your fault.’ And I’ll see the child glance over to the parent and I’ll know there’s been a lot of conflict.”  In 1995, the first news of a genetic basis for bed-wetting made headlines, after Danish researchers reported a link to Chromosome 13. “It’s very clear that there is a strong hereditary component in the course of enuresis,” said Dr. Soren Rittig, a professor of pediatric nephrology at Aarhus University Hospital in Denmark.  Dr. Rittig is one of a group of researchers who have published new findings on the genetics of nocturnal enuresis, which turn out to be far from simple; linkage to three other chromosomes has been found in other families.  The researchers identified several large families in which enuresis was inherited following an autosomal dominant pattern  that is, if either parent has a history of bed-wetting, a child has a 50 percent chance of inheriting it.  As children grow older than my patient, behavioral and other treatments can make a big difference. Children whose bladders tend to spasm can be treated with anticholinergic drugs, and children who lack an antidiuretic hormone can take a synthetic version.  But these drugs treat the symptom, not the underlying problem. “I consider enuresis to be a developmental delay which will improve by itself,” Dr. Abidari said, adding that if the medication is stopped and development has not progressed, “they will wet again.”  In such cases an effective treatment is a bed alarm, which vibrates and makes a noise when a child starts to urinate. Dr. Abidari says the alarms can cure the problem but can be hard on families, especially if the child is a sound sleeper. “The alarm goes off, everybody in the household wakes up but the child is still asleep,” she said. Success, she said, requires motivation on everyone’s part.  The doctors, nurse practitioners and counselors who treat enuresis can be almost messianic about the relief they can offer children and families. “The physician has to have an enthusiasm for wanting to treat wetters,” said Dr. Kenneth I. Glassberg, director of pediatric urology at Morgan Stanley Children’s Hospital of NewYork-Presbyterian.  There must also be a committed staff, he added, to handle the frequent visits, phone calls and long-term support the children and their families may need.  All children with wetting problems should be checked for urinary tract infections. Children who develop secondary enuresis  that is, they are fully dry for six months, then begin wetting again  may have infections, constipation (an overly full bowel can put pressure on the bladder) or a variety of other problems, including behavioral and psychological issues.  My patient was also having some daytime accidents, and many specialists would want to address those even before age 5. The same bladder problems may be at work, but there can also be behavioral components.  In addition to anatomical and hormonal factors, “developing continence day and night is a combination of neurological readiness, developmental readiness and the interplay between a child and his environment, whether that’s day care, parents, sibling, preschool,” said Dr. Alison D. Schonwald, an assistant professor of pediatrics at Harvard Medical School and the co-author of “The Pocket Idiot’s Guide to Potty Training Problems” (Alpha, 2006).  My plan was to check the 5-year-old’s urine, just to make sure she didn’t have an infection, and to offer a referral to a pediatric urologist. Although the patient’s mother felt that the daytime problems were improving, she was happy to see a specialist. And the child herself demonstrated her bladder control by flatly refusing to urinate in a plastic cup.
The causes for bed-wetting in children can be genetic, developmental and physiological, but the problem itself is quite treatable.