THALIDOMIDE
THERMOMETER
T
trait), which is never severe, is caused by
1 defective gene. The presence of 2 defec-
tive genes causes beta-thalassaemia
major (Cooley's anaemia). The much
rarer disorder alpha-thalassaemia varies
in severity; alpha-thalassaemia major
usually results in fetal death.
Symptoms of beta-thalassaemia major
appear 3-6 months after birth. If un-
treated, bone marrow cavities expand,
leading to a characteristic enlargement
of the skull and facial bones.
Beta-thalassaemia major is diagnosed
from microscopic examination of the
blood, and from other
blood tests.
Treat-
ment is with
blood transfusions
and,
sometimes,
splenectomy.
However, suc-
cessive
blood
transfusions
cause
a
buildup of iron in the body (see
haemo-
siderosis
).
Chelating agents
are given by
continuous infusion to help the body
excrete the excess iron. A
bone marrow
transplant
offers a cure for the disease.
Genetic counselling is advised for par-
ents or other close relatives of a child
with thalassaemia, and also for any per-
son with thalassaemia trait.
thalidomide A drug that was withdrawn
in the UK in 1961 after it was found to
cause limb deformities in many babies
born to women given the drug during
pregnancy. Thalidomide is still used to
treat certain forms of
Hansen's disease
(leprosy) and
Behget's syndrome.
thallium A rare metallic element that is
present as compounds in some zinc and
lead ores. Poisoning over a prolonged
period causes loss of hair, disorders of
the nerves in the limbs, and disturbance
of the stomach and intestines. Thallium-
201
(an artificial radioactive isotope) is
sometimes used in
radionuclide scan-
ning
of the heart.
THC The abbreviation for tetrahydro-
cannabinol, the active ingredient in
marijuana.
theophylline A
bronchodilator drug
some-
times used to treat severe
asthma
and
heart failure
in cases that have failed to
respond to other treatments. Theophyl-
line is usually given orally but can be
given intravenously as emergency treat-
ment. Possible adverse effects include
dizziness, nausea, vomiting, diarrhoea,
palpitations,
and
seizures.
therapeutic A term meaning related to
treatment. The therapeutic dose of a
drug is the amount required to have the
greatest beneficial effect.
therapeutic community A method of
treating
drug dependence
and
alcohol
dependence
, and some
personality dis-
orders
,
that
entails
patients
living
together as a group in a nonhospital
environment,
usually
under
super-
vision. (See also
social skills training.)
therapy The treatment of any disease or
abnormal physical or mental condition.
thermography A technique by which
temperature patterns on the surface of
the skin are recorded in the form of an
image. Thermography provides clues to
the presence of diseases and abnormal-
ities that alter the temperature of the
skin, such as problems of the circulation,
inflammation, and tumours. There are 2
types of thermography. In one, a camera
or scanner picks up infrared radiation
naturally emitted from the skin. In the
other, sheets of temperature-sensitive
liquid crystals are applied to the skin;
they change colour in response to
changes in temperature.
thermometer An instrument used to
measure
temperature
. A traditional clin-
ical thermometer consists of a glass
capillary tube (a tube with a very fine
bore) that is sealed at one end and has
a mercury-filled bulb at the other.
Modern versions of the clinical therm-
ometer
include
an
electronic probe
connected to a digital display, and an
aural thermometer, which measures the
THERMOMETER
USING AN AURAL THERMOMETER
546
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