Enuresis 153enuresis; these studies have implicated different chromosomal sites in
different families. This may reflect the existence of many relevant genes,
each of which is rare but potentially powerful.
Environmental factors also seem to play a part.
1 Enuresis is associated withurinary tract infections(UTIs), particularly in
girls. Thus in 5-year-old girls, asymptomatic UTIs are present in about
5% of those with enuresis, as opposed to about 1% of those without.
The likelihood of associated UTIs is even higher if the enuresis is diurnal
or particularly frequent.
2 Stressful life eventsat the age of 3–4 are associated with twice the risk
of enuresis. Relevant events include family break-up, separation from
parents, moving house, the birth of a sibling, admission to hospital and
accidents. Recurrent hospital admission is particularly associated with
bed-wetting. Sexual abuse is associated with secondary enuresis.
3 Enuresis is associated with several indicators ofsocial disadvantage:lower
socio-economic status, an overcrowded home and institutional care.
4 Startingtoilet trainingafter 20 months is associated with a higher rate
of subsequent enuresis. Otherwise, the role of specific toilet training
practices is unclear. Harsh training seems undesirable since it is more
upsetting for the child, but there is no evidence that it results in more
enuresis.
Pathophysiology
1 Two-thirds of nocturnal enuresis involves some combination of two
underlying problems:
(a)In most children and adolescents, the rate of urine production falls
at night as a result of increased nocturnal secretion of antidiuretic
hormone. This can reduce the quantity of urine that accumulates
in the bladder overnight to an amount that the individual can hold
in their bladder without waking or wetting themselves. Nocturnal
enuresis is associated with a high rate of urine production at night –
either they secrete unusually little antidiuretic hormone levels at
night or their kidneys are resistant. As a result, bladder capacity
is reached rapidly. Pointers to this pattern of nocturnal enuresis
include large wet patches and the first episode of wetting occurring
fairly soon after going to sleep. A lack of antidiuretic hormone at
night can be treated by taking desmopressin (an artificial equivalent
of antidiuretic hormone) before sleep (see below).
(b)Reaching bladder capacity would not result in bed wetting if the
individual woke up and went to the toilet. However, enuresis is also
associated with a reduced likelihood of waking up in response to the
sensation of a full bladder. Contrary to what many families suspect,
this is not due to sleeping unusually deeply. Enuresis can occur at
any stage of sleep and individuals with enuresis do not sleep more
deeply than other people. An enuresis alarm can help the individual
to learn to wake up in response to a full bladder (see below).