HOOKWORM INFESTATION
HOT FLUSHES
H
2
different alleles controlling that trait.
(See also
inheritance; genetic disorders.)
hookworm infestation
An infestation
of the small intestine by small, round,
blood-sucking worms of the
necator
AMERICANUS
or
ANCYLOSTOMA DUODENALE
species. Hookworm infestation occurs
mainly in the tropics.
The larvae penetrate the skin of the
feet or are ingested. They migrate
throughout the body and mature in the
small intestine. Adult worms lay eggs,
which pass out in the faeces.
When larvae penetrate the skin, a red,
itchy rash may develop on the feet. In
light infestations, there may be no fur-
ther symptoms. In heavier infestations,
migration of the larvae through the lungs
may produce cough and
pneumonia
;
adult worms in the intestines may
cause abdominal discomfort. The most
important problem is iron-deficiency
anaemia
due to loss of blood.
Diagnosis is made by microscopic ex-
amination of the faeces for worm eggs.
Anthelmintic drugs
kill the worms. (See
also
larva migrans
.)
hordeolum
The medical name for a
stye
.
hormonal disorders
Conditions caused
by malfunction of an
endocrine gland.
hormone
A chemical released into the
bloodstream by a gland or tissue that
has a specific effect on tissues else-
where in the body.
Many hormones are produced by
endo-
crine glands
. Hormones are also secreted
by other organs, including the brain,
kidneys, intestines, and, in pregnant
women, the
placenta
. They control many
body functions, including
metabolism
of
cells, growth, sexual development, and
the body's response to stress or illness.
hormone antagonist
A drug that blocks
the action of a
hormone.
hormone replacement therapy (HRT)
The use of a synthetic or natural
hor-
mone
to treat a hormone deficiency.
Most commonly, HRT refers to the use
of female hormones to relieve symptoms
associated with the
menopause
, such as
hot flushes and vaginal dryness. HRT
also reduces the risk of the long-term
effects associated with low
oestrogen
levels, such as
osteoporosis
. An oestro-
gen is usually taken in combination
with a
progestogen
.
The hormones may
be taken orally or released into the
bloodstream from a hormonal implant,
skin patch, or gel.
Minor adverse effects of HRT include
nausea, breast tenderness, fluid reten-
tion, and leg cramps. In some women,
oestrogen therapy may increase the risk
of abnormal blood clotting. Women tak-
ing HRT in the long term are thought to
be at a slightly increased risk of breast
cancer, but are thought to be less likely
to develop
coronary artery disease
.
horn, cutaneous
A hard, noncancer-
ous protrusion occasionally found on
the skin of elderly people and caused by
an overgrowth of
keratin
.
Horner's syndrome
A group of phys-
ical signs (narrowing of the eye pupil,
drooping of the eyelid, and absence of
sweating
)
affecting
1
side of the face
that indicates damage to part of the
sympathetic nervous system (see
auto-
nomic nervous system
).
horseshoe kidney
A
congenital
abnor-
mality in which the
2
kidneys are fused
at the base, forming a horseshoe shape.
The joined kidneys usually function
normally, but may be associated with
other congenital kidney defects.
hospice
A hospital or part of a hospital
devoted to the care of patients who are
terminally ill (see
dying, care of the
).
hospitals, types of
Most of the hospitals
in the UK are part of the National Health
Service. Each NHS district has a general
hospital providing services that include
medicine, surgery,
gynaecology
,
obstetrics
,
and
paediatrics
. Some more specialist
services are concentrated in fewer cen-
tres. Many of the UK's private hospitals
are nursing homes for the elderly; others
cater for nonemergency surgery, obstetric
care, or inpatient care for the mentally ill.
hot flushes
Temporary reddening of the
face, neck, and upper trunk that is
accompanied by a sensation of heat
and is often followed by
sweating
. Hot
flushes are usually caused by decreased
oestrogen
production during or after the
menopause
, and they sometimes occur
following removal of the ovaries (see
oophorectomy
). Hot flushes can often
be alleviated by treatment with
hor-
mone replacement therapy (HRT)
.
286
previous page 284 BMA Illustrated Medical Dictionary read online next page 286 BMA Illustrated Medical Dictionary read online Home Toggle text on/off