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Bedwetting
A common but rarely serious problem

Many kids, especially boys, continue to wet the bed until they are almost in their teens. At age five, between 15 to 25 per cent of children still wet the bed whether every night or only once in a while. By age 12, the amount of even occasional bedwetting drops to about eight per cent of boys and four per cent of girls. Many social problems are attached to bedwetting (nocturnal enuresis), so it is certainly a significant social concern. Fortunately, bedwetting is rarely due to a major medical concern.

Most often, the system that reduces production of urine overnight is slow to mature. Once this system develops, children (and adults) are able to sleep through the night without having to get up to go to the bathroom. More rarely, bedwetting may be caused by a significant medical problem. A detailed investigation may be required to fully diagnose the problem.

More and more, evidence suggests that bedwetting is physiological (caused by a problem with the body). The idea that it is psychological (for instance, that the child wets the bed to punish the parents) has fallen out of favour. The psychological approach might explain an odd night with bedwetting, but not an ongoing situation.

The first step in managing bedwetting involves having your family doctor take a detailed history to identify simple or more serious causes. Parents can provide most of the details needed for the first screening. Only limited information can be gained by a routine examination or by simple laboratory tests.

First, has the child always wet the bed? If so, the condition is called primary nocturnal enuresis. Alternatively, the child may have been dry for a time (usually over six months) but is now wetting the bed again. This is called secondary nocturnal enuresis. The causes of these two types of bedwetting are usually quite different.

Secondary enuresis is often caused by a bladder infection. A simple urine test can be done in the office. If there is an infection, a short course of antibiotics will cure it quickly. One or two bladder infections in a young girl aren’t cause for concern, but more may warrant a referral. After even one bladder infection, a young boy may also be referred to the same pediatric urologist, who works with children who have problems with the urine system. The doctor runs a variety of tests to make sure the infection is not caused by a problem with the child’s anatomy. The urologist can help identify the cause of bedwetting and develop a solution.

In cases where the child has always wet the bed, primary nocturnal enuresis is usually caused by one of three basic problems. Too much urine may be made overnight, there may too little room in the bladder, or the child may not wake when the bladder is full. Two or three of these problems sometimes combine to result in bedwetting.

By far the most common problem is when too much urine is made overnight. Normally, the brain makes anti-diuretic hormone or ADH to reduce the production rate of urine. Though very few people can go eight hours during the day without going to the bathroom, most do so every night. During sleep, the brain steps up production of ADH and cuts down on that of urine during sleep. As a result, it is possible to sleep for many hours without needing to urinate.

In young children, the timing for release of ADH is not well controlled. Often the level of ADH levels does not rise overnight, so the child needs to pass urine. Since the ADH production pattern matures as a child grows, many develop the ability to sleep all night without bedwetting. However, hormone production isn’t the same from day to day. On some nights, high levels of ADH mean low urine production and no bedwetting. On other nights when ADH is low, bedwetting may result.

The family doctor can often identify a problem with ADH levels since bathroom habits are otherwise normal. Typically there is no problem with bladder control during the day. The child visits the bathroom several times during waking hours, producing a large amount of urine each time. In comparison to other children of the same age, a similar amount of fluid is drunk and urine is not unusually concentrated.

If the bedwetting child fits this pattern, a drug called desmopressin can often help. This synthetic form of ADH acts to reduce urine production. It is taken in the evening before bed. About 70 per cent of all children with bedwetting problems respond well to this drug. The bedwetting problem is greatly reduced in seriousness, and often it is completely resolved.

Even without treatment, most kids outgrow the problem sometime before the age of seven. The production of ADH gradually develops an adult pattern and less urine is made while sleeping, so the child does not have to pass urine while asleep.

If desmopressin doesn’t work, there is a good chance that the problem lies either in low bladder capacity or failure to waken when the bladder signals it is full. Bladder capacity problems can arise from a variety of causes. Finding the exact nature of the problem often requires sophisticated investigation by specialists.

Questioning the child and parents about capacity problems may or may not help. Sometimes a child visits the bathroom more often than other children their age and produce relatively small amounts of urine on each visit.

However, some children learn to control the number of bathroom visits they need by reducing the amount of fluid they drink. These kids make a normal number of trips to the bathroom during the day, but only produce a little bit of urine each time. Chemical analysis of the urine shows that it is unusually concentrated. It will also have abnormal levels of various salts and other chemicals.

Parents are not usually able to answer questions about the amount and concentration of urine passed each time. Some children who seem to have normal bathroom patterns will receive desmopressin. If they don’t respond well to the drug, perhaps the actual cause is not being addressed.

Depending on the exact nature of the bladder capacity problem, several other drugs may help. Since most have significant side effects, they are usually used only after a detailed investigation suggests a role for them. Bladder capacity problems are complicated by the fact that affected children simply do not wake up when the bladder signals it is full. In contrast, children who do not wet the bed will wake up when the brain receives the full signal. Despite much investigation, there is still no suggested reason for this difference. Nor is there a treatment to make these children wake up more easily.

Considerable effort has been devoted to finding non-drug treatments for bedwetting. The two most common approaches involve alarms and behaviour therapy. Both are relatively ineffective and require a great deal of work by the parents.

Most kids stop bedwetting on their own while still quite young. If bedwetting is causing a social problem, desmopressin may help. Only a few children need help from a specialist. Your family doctor can advise on whether your child needs desmopressin or a referral to a specialist.