HYPERTHERMIA
HYPERVENTILATION
stopping smoking.
Biofeedback training
and relaxation techniques can help
reduce blood pressure. If self-help mea-
sures have no effect, or hypertension is
severe, 1
or a combination of
antih}sper-
tensive drugs
may be given,
hyp ertherm ia A medical term for very
high body temperature,
hypertherm ia, m alignant A rapid rise
in body temperature to a dangerously
high level, brought on by general
anaes-
thesia.
The condition is rare. In most
cases, susceptibility is inherited; people
suffering from certain muscle disorders
may also be at risk. The patient's body
temperature rises soon after the anaes-
thetic is given. Emergency treatment and
intensive care are needed.
hyperthyroidism
The overproduction
of
thyroid hormones
by an over active
thyroid gland
. The most common form
of hyperthyroidism is
Graves' disease,
which is an
autoimmune disorder
. Less
commonly, the condition is associated
with the development of enlarged nod-
ules within the thyroid gland.
The characteristic signs of hyperthy-
roidism include weight loss, increased
appetite, increased
sweating
, intolerance
to heat, a rapid
heart-rate
, and protrud-
ing eyes. In severe cases, the thyroid
gland often becomes enlarged (see
goitre
) and there is physical and mental
hyperactivity and muscle wasting.
The diagnosis of hyperthyroidism is
confirmed by measuring the level of
thyroid hormones present in the blood.
The condition can be treated with drugs
that inhibit the production of thyroid
hormones or by removal of part of the
thyroid gland.
hypertonia
Increased rigidity in a mus-
cle, which may be caused by damage to
its nerve supply or changes within the
muscle. Hypertonia causes episodes of
continuous muscle spasm. Persistent
hypertonia in limb muscles following a
stroke
or
head injury
leads to
spasticity
.
hypertrichosis
Growth of excessive
hair,
often in places that are not normally
hairy. Hypertrichosis often occurs as a
result of taking certain drugs (including
ciclosporin
and
minoxidil
). The term
hypertrichosis is also used to describe
hair growth in a mole. Hypertrichosis is
HYPERTRICHOSIS
not the same as
hirsutism
, which is due
to abnormal levels of male hormones.
hypertrophy
Enlargement of an organ
or tissue due to an increase in the size,
rather than number, of its constituent
cells. For example, skeletal muscles
enlarge in response to increased physi-
cal demands. (See also
hyperplasia.)
hyperuricaemia
An abnormally high
level of
uric acid
in the blood. Hyperuri-
caemia may lead to
gout
due to the
deposition of uric acid crystals in the
joints; it may also cause kidney stones
(see
calculus, urinary tract
)
and
tophus.
Hyperuricaemia may be caused by an
inborn error of metabolism (see
metab-
olism, inborn errors of
), by the rapid
destruction of cells in a disease such
as
leukaemia
, or by medication that
reduces the excretion of uric acid by the
kidneys, such as
diuretic drugs.
Large
amounts of
purine
in the diet may also
cause hyperuricaemia.
Drugs such as
allopurinol
or
sulfin-
pyrazone
are prescribed for the duration
of the patient's life. Purine-rich foods
should be avoided.
hyperventilation
Abnormally deep or
rapid breathing that is usually caused
by
anxiety
. Hyperventilation may also
occur as a result of uncontrolled
dia-
betes meUitus,
oxygen deficiency,
kidney
failure
, and some lung disorders.
Hyperventilation causes an abnormal
loss of carbon dioxide from the blood,
which can lead to an increase in blood
alkalinity. Symptoms include numbness
of the extremities, faintness,
tetany
, and
293
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