Water Intoxication Alert
Due to a medical crisis where a young person with PWS ended up in intensive
care with a possible diagnosis of water intoxication, I e-mailed our medical
boards about the situation. The following responses are from physicians with
experience regarding PWS and water toxicity. We’re sharing their thoughts here
to make the PWS community aware of this potential medical condition ~
Janalee Heinemann, Medical Director
Water intoxication is well known to occur in children and adults with eating
disorders regardless of mental abilities, and also in individuals who are
severely retarded. This is not a new phenomenon. I am frankly surprised that it
doesn’t occur more often in PWS.
We have seen this type of situation several times. In my opinion, anyone who
drinks 72 oz. (9 x 8 oz. ) is drinking too much water, unless he or she is in a
situation such as intense exercise and/or in a hot climate where there is a high
rate of water loss. We have been trying to restrict intake to 1- 1/2 quarts per
day. I would think that even some “normal” people who drink that much water
daily would be at risk for hyponatremia.
We have had several of our patients with PWS worked up by adult
endocrinologists with no specific findings, except one who might be mildly
deficient in anti-diuretic hormone (ADH), and most of the time, he does not take
his DDAVP and keeps a normal sodium with a restricted fluid intake. I think that
this case is probably water intoxication, such as happens in many major cities,
usually in babies who have parents who do not know better than to feed water to
The problem of water intoxication is a difficult one and may be related to
two different physiological mechanisms: some of the patients we have seen have
compulsive water drinking and often need to be restricted and/or monitored in
order to keep their electrolytes in balance; this seems to be a problem related
to the PWS itself.
On the other hand there is a syndrome called SIADH, which is related to a
problem the kidney has in filtering out the excretions, and in this case the
kidney absorbs too much water. This problem may be related to medications, may
occur with other psychiatric maladies and may occur unrelated to all of these.
The latter situation is much more likely to throw the electrolytes out of order,
as the body usually seems designed to handle fluids without throwing
electrolytes off. However, for the person with PWS this may be more complicated
because of right heart failure, and decidedly needs to be reviewed and handled
by a pediatrician/internist.
This person needs to be fluid restricted, but much more importantly, this
person needs to be evaluated by a good endocrinologist (and perhaps a
neurologist as well). It may be SIADH, but several tests are needed before a
diagnosis and treatment plan are made. Water toxicity can be very dangerous.
I would be skeptical about water intoxication. What you haven’t said is what
medications the individual was on or if there were other medical issues. It is
possible that this may be a case of SIADH that can have a host of causes. In
SIADH, there is an inappropriate release of anti-diuretic hormone that causes
water retention and can cause this severe of hyponatremia. Also when you said
the kidneys were normal, what studies were used? Without more information, this
is all speculation, but the amount of water we are told was consumed should be
adequately handled by normally functioning kidneys as long as there is not an
underlying problem like SIADH.
There are two issues: first, identifying individuals at risk and situations
in which risk is increased for all individuals; second, protection and
Individuals at risk are those who consume large amounts of fluids daily where
the majority of fluid consumed is water. Specific high-risk situations occur
when fluids such as sweat, diarrhea, etc. — that is, fluids containing salt —
are lost and then replaced with water, which obviously contains no salt. Certain
medications and medical conditions also have a likelihood of causing SIADH that
others have referred to.
For those few individuals at risk, prevention is first the identification, to
ensure that they don’t have unlimited access to water; individuals who sweat a
lot in the summer, etc., need to properly replace lost fluid with fluids such as
Gatorade. Providers and families also need to understand the potential
seriousness of the problem.