Bed wetting in children is usually divided into two main categories, primary bedwetting (ninety percent) and secondary bedwetting (five to ten percent).
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Children with primary bedwetting have never experienced an extended period of dryness (two to three months) without the use of some type of treatment or medication. The usual cause of primary bedwetting is an irritable bladder with too small a capacity.
Secondary bedwetting occurs when a child has stopped bedwetting for an extended period of time (usually six months) and then resumes. Such factors as diabetes, urinary tract (kidney, bladder) abnormalities, anatomic abnormalities, and psychological factors may cause secondary bedwetting.
In rare cases, bedwetting can be the result of narrowing of the end of the urethra (tube that carries urine from the bladder to the outside), which can be widened through stretching. BUT THIS IS RARE!
Children with secondary bedwetting often have problems associated with the complex of attention deficit disorders (ADD).
Causes of bed wetting
There are three common causes that have been associated with bedwetting:
- Difficulty awakening from sleep to go to the bathroom when the bladder is full.Many children with appear to sleep very deeply and research has shown that occurs during all stages of sleep, not just the deepest stage. It is the child's inability to wake up to the sensation of a full bladder and then hold his urine long enough to get to the bathroom that contributes to the problem. Difficulty awakening from sleep
- About one-third of children who wet at night have small capacity bladders so they are not able to make it through the night. These children are only able to hold about 70 percent of what is an age-appropriate bladder volume. The result is bedwetting before their bladders are actually full. These children may also experience urinary urgency during the day, or may void more frequently than their peers. They experience overactive bladder contractions as their bladder fills with urine.
- Increased volume of urine in the bladder (called nocturnal polyuria)
The normal nighttime release of antidiuretic hormone (ADH), arginine vasopressin, results in a lower urine production during the night. It has been postulated that some children who bed-wet lack an adequate level of nighttime ADH, which causes a higher nighttime urine production than their bladders can accommodate.
Genetics may also place a child at increased risk for bedwetting. It is not uncommon for a child to have a parent, aunt or uncle who also wet the bed growing up. If both parents had nocturnal enuresis, there is a 77 percent chance that their child will be affected; if only one parent wets, the child has a 44 percent chance of bedwetting. It appears that an abnormality on chromosome thirteen is responsible for the condition. Children are often relieved to learn that another family member had the same condition.
There are other causes of bedwetting such as:
- Conditions that cause polyuria must be ruled out, particularly in a new onset of . These include diabetes insipidus, diabetes mellitus, chronic renal disease and excessive water drinking. nocturnal enuresis.
- Medications, including diuretics, theophylline, and lithium can cause polyuria, and urinary frequency and/or retention (incomplete bladder emptying) have been associated with some classes of antidepressant drugs. Sedating medications given at bedtime or in the late evening can make it difficult for a child to wake up during the night to void.
- Urinary tract infections and constipation can cause increased bladder irritability, a reduced functional bladder capacity and wetting.
- Structural or anatomic causes (such as a narrowed urethral) of bedwetting are rare.
1. Berry, AK. Helping Children with Nocturnal Enuresis. AJN. 2006;106(8):58-65.
Posted August 2006
Updated August 2009