not the same as hirsutism, which is due
to abnormal levels of male hormones.
hypertrophyEnlargement 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.)
hyperuricaemiaAn abnormally high
level of uric acidin the blood. Hyperuri-
caemia may lead to goutdue 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 purinein the diet may also
cause hyperuricaemia.
Drugs such as allopurinolor sulfin-
pyrazoneare prescribed for the duration
of the patient’s life. Purine-rich foods
should be avoided.
hyperventilationAbnormally deep or
rapid breathing that is usually caused
by anxiety. Hyperventilation may also
occur as a result of uncontrolled dia-
betes mellitus, 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, andHYPERTRICHOSIS
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 antihyper-
tensive drugsmay be given.
hyperthermiaA medical term for very
high body temperature.
hyperthermia, malignantA 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.
hyperthyroidismThe overproduction
of thyroid hormonesby an overactive
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.
hypertoniaIncreased 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
strokeor head injury leads to spasticity.
hypertrichosisGrowth 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
HYPERTHERMIA HYPERVENTILATION
FEMALE WITH HYPERTRICHOSIS H
Abnormal hair growth