Involuntary weight loss is defined as a decrease
of at least 5% of body weight in a 6 month period
that isn't due to dieting, diuretic use or medical
diseases known to affect weight. If you are overweight,
you may wish for this, but if you or a friend are
losing weight unintentionally, it needs to be diagnosed
so there is not an increased risk of disease or dying.
Many times, involuntary weight loss is associated
with elderly adults but it is possible to happen to
anyone. Up to 8% of patients presenting to primary
care physicians complain of weight loss. In 25% of
those, no cause for the weight loss is ever found.
A recent review paper, Bianchi A, Toy EC, Baker B
III: The evaluation of involuntary weight loss. Prim
Care Update Ob/Gyns 1998;5:263-267, categorized three
basic causes of weight loss:
decreased intake - the most common cause, most often
in teenagers and elderly adults
increased fluid-nutrient loss - associated with malabsorption
and diabetes
excess metabolic demand - malignancies often associated
with gastrointestinal tract, genitourinary system
and breast
It is important to document the fact that weight
loss is taking place. Believe it or not, many who
complain of involuntary weight loss have no weight
change by objective documentation. There are some
factors, however, that are diagnostic predictors of
underlying illness:
recent change in cough
nausea or vomitting
a 20 pack-year history of smoking
a recent change in appetite
a decrease in activity due to fatigue
an abnormality on physician's physical examination
If the cause of weight loss is not obvious, the physician
should check initial laboratory tests including CBC,
HIV, blood chemistry, urinalysis, thyroid function,
chest xray and routine recommended cancer screening.
The following specific diseases may be present.
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