reduce nausea in Ménière’s disease. It is
also used in eye-drops to dilate the pupil
before an eye examination or surgery.
An injection of hyoscine hydrobromide
is often given as part of a premedication
because it dries secretions in the mouth
and lungs. Possible adverse effects of
both forms include dry mouth, blurred
vision, drowsiness, and constipation.
hyper-A prefix meaning above, exces-
sive, or greater than normal.
hyperacidityA condition in which ex-
cess acid is produced by the stomach.
Hyperacidity is often confused with acid
reflux or waterbrash. It occurs in people
with a duodenal ulcer (see peptic ulcer)
or Zollinger–Ellison syndrome.
hyperactivityA behaviour pattern in
which children are overactive and have
difficulty in concentrating. The occasional
occurrence of such behaviour in small
children is considered normal. However,
persistent hyperactivity is known as
attention deficit hyperactivity disorder
(ADHD), which may require treatment.
hyperacusisAn excessively sensitive
sense of hearing. In hyperacusis, expo-
sure to loud noises may cause pain or
discomfort in the ears.
hyperaldosteronismA metabolic dis-
order caused by an overproduction of
the hormone aldosteroneby the adrenal
glands(see aldosteronism).
hyperalimentationAdministration of
excessive amounts of calories, usually
intravenously or by stomach tube (see
feeding, artificial).
hyperbaric oxygen treatmentA meth-
od of increasing the amount of oxygen
in the tissues. This is achieved by plac-
ing a person in a special chamber and
exposing him or her to oxygen at a
much higher atmospheric pressure than
normal. Hyperbaric oxygen treatment is
used to treat poisoning from carbon
monoxideand in cases of gas gangrene.
hyperbilirubinaemiaA raised blood
level of bilirubin. It may be undetectable
except by a blood test, but jaundice
occurs if the blood bilirubin rises to
twice the normal level.
hypercalcaemiaAn abnormally high
level of calciumin the blood, commonly
caused by hyperparathyroidism.Cancer
may also cause hypercalcaemia, eitherby spreading to bone or producing
abnormal hormones that cause bones
to release calcium. Less commonly, the
condition is a result of excessive intake
of vitamin Dor of certain inflammatory
disorders, such as sarcoidosis.
Hypercalcaemia causes nausea, vom-
iting, lethargy, depression, thirst, and
passing urine excessively. Higher blood
levels of calcium produce confusion,
extreme fatigue, and muscle weakness.
Without treatment, the condition can re-
sult in cardiac arrhythmias, kidney failure,
coma, and even death. Long-standing
hypercalcaemia may cause nephrocalci-
nosis or kidney stones (see calculus,
urinary tract). Diagnosis is by blood tests.
Treatment is of the underlying cause.
hypercapniaExcessive carbon dioxide
in the blood caused by failure of mech-
anisms, such as breathing rate, that
normally control the carbon dioxide
levels in the blood. Hypercapnia leads
to respiratory acidosis.
hyperemesisThe medical term for
excessive vomiting, which may cause
dehydration and weight loss. When the
condition occurs in pregnancy, it is
known as hyperemesis gravidarum.
hyperglycaemia An abnormally high
level of glucosein the blood that occurs
in people with untreated or inadequately
controlled diabetes mellitus. Hyperglycae-
mia may also occur in diabetics as a
result of an infection, stress, or surgery.
Features of the condition include passing
large amounts of urine, thirst, glycosuria,
and ketosis. If severe, hyperglycaemia
may lead to confusion and coma, which
need emergency treatment with insulin
and intravenous infusionof fluids.
hypergonadismOveractivity of the go-
nads (testesor ovaries) that results in
overproduction of androgen hormones
or oestrogen hormones. Hypergonadism
may be due to disorders of the gonads
or a disorder of the pituitary glandthat
results in overproduction of gonado-
trophin hormones. During childhood,
the condition causes precocious sexual
development and excessive growth.
hyperhidrosisExcessive sweating, which
may be localized (affecting only the arm-
pits, feet, palms, or face) or affect all
body areas supplied by sweat glands.HYPER- HYPERHIDROSISH