HYDROCHLORIC ACID
HYOSCINE
epilepsy
,
irritability, lethargy, and the
absence of normal reflex actions. If it is
not treated, hydrocephalus progresses
to severe brain damage, which may
result in death within weeks. When the
condition occurs later in life, symptoms
include headache, vomiting, loss of
coordination, and the deterioration of
mental function.
In most cases, treatment of hydro-
cephalus is by draining the fluid from
the brain to another part of the body,
such as the abdominal cavity, where it
can be absorbed.
hydrochloric acid
A strong acid re-
leased by the stomach lining. This acid
forms part of the stomach juices and
helps to digest proteins.
hydrochlorothiazide
A
thiazide diur-
etic drug
used to reduce
oedema
in
people with
heart failure
,
nephrotic syn-
drome
,
and
cirrhosis
.
It is also given for
hypertension
. Adverse effects include
leg cramps, dizziness, rash, and impo-
tence. The drug may rarely cause
gout
and may aggravate
diabetes meUitus
.
hydrocortisone
A
hormone
produced
naturally by the
adrenal glands
.
Syn-
thetic hydrocortisone is used as a
corticosteroid drug
to treat inflammatory
or allergic conditions, such as
ulcerative
colitis
or
dermatitis
.
Used in excess, hydro-
cortisone creams may thin the skin.
hydrogen peroxide
An
antiseptic
sol-
ution used to treat infections of the skin
or mouth and to bleach hair.
hydronephrosis
A condition in which
a
kidney
becomes swollen with urine as
a result of an obstruction in the
urinary
tract
.
Many people with hydronephrosis
have a
congenital
narrowing of the
ure-
ter
. The obstruction of a ureter may be
caused by a stone (see
calculus, urinary
tract
),
a
kidney tumour
,
or a blood clot.
Occasionally, hydronephrosis is caused
by obstruction to the outflow of urine
from the bladder by an enlarged pros-
tate gland (see
prostate
,
enlarged
).
Acute hydronephrosis, with sudden
blockage of the ureter, causes severe
pain in the loin. Chronic hydronephro-
sis, in which the obstruction develops
slowly, may cause no symptoms until
total blockage results in
kidney failure
.
If
the blockage can be removed surgically,
the kidney is likely to function normally
again. Occasionally, however, a kidney is
so badly damaged that it requires re-
moval (see
nephrectomy
).
hydrophobia
A popular term, now al-
most obsolete, for
rabies
.
hydrops
An abnormal accumulation of
fluid in body tissues or in a sac.
hydrops fetalis
Serious swelling, or
oedema,
that occurs in a
fetus
before
birth. Hydrops fetalis is often the result
of
Rhesus incompatibility
(see
haemolytic
disease of the newborn
).
hydrotherapy
The use of exercises in
water to aid recovery from injury or
improve mobility. Cold baths after an
injury can reduce swelling and bruising.
(See also
heat treatment; ice-packs.)
hydroxocobalamin
A long-acting syn-
thetic preparation of
vitamin B12,
given
by injection.
hygiene
The science and practice of
preserving health. The word hygiene is
commonly equated with cleanliness, but
it can also refer to
public health
.
hygiene, oral
See
oral hygiene
.
hygroma, cystic
A
lymphangioma
that
occurs around the head and neck, the
armpits, or the groin and contains clear
fluid. Cystic hygromas are usually pre-
sent from birth and disappear naturally
from the age of about 2.
hymen
The thin membrane around the
vaginal opening. The hymen has a central
perforation which is usually stretched
or torn by the use of tampons or during
sexual intercourse for the 1st time.
Imperforate hymen is a rare condition
in which the hymen has no perforation;
at the onset of menstruation, menstrual
blood collects in the
vagina
, causing
lower abdominal pain. The condition is
easily corrected by a minor operation.
hyoid
A small, U-shaped bone situated
centrally in the upper part of the neck. It
is not joined to any other bone but is
suspended by ligaments from the base
of the skull. It provides an anchor point
for the muscles of the tongue and of the
upper front part of the neck.
hyoscine
An
anticholinergic drug
pre-
scribed in 2 distinct forms. Hyoscine
butylbromide is used to relieve
irritable
bowel syndrome
. Hyoscine hydrobromide
is used to control
motion sickness
and to
H
289
previous page 287 BMA Illustrated Medical Dictionary read online next page 289 BMA Illustrated Medical Dictionary read online Home Toggle text on/off