the bloodstream to the lungs. This is
known as a
p u lm o n a r y e m b o lis m
A diagnosis is made by doppler
u lt ra -
s o u n d s c a n n in g
Treatment depends on
the site and extent of the clots. Small
clots may not need treatment if they are
confined to the calf and the patient is
mobile. Otherwise,
a n tic o a g u la n t d ru g s
th ro m b o ly tic d ru g s
are given. If there is a
high risk of pulmonary embolism,
th ro m -
b e c t o m y
(surgical removal of the clot)
may be performed.
The risk of deep vein thrombosis dur-
ing long-haul flights can be reduced by
wearing elastic stockings, moving the
legs and feet around frequently, and
drinking plenty of nonalcoholic fluids.
th ro m b u s
A blood clot that has formed inside an
intact blood vessel. A thrombus is life-
threatening if it obstructs the blood
supply to an organ such as the heart or
brain. A thrombus may also lead to
g a n -
g r e n e
(tissue death)
in an organ or
extremity, or to
e m b o lis m
in w hich a
fragment of the thrombus breaks off
and is carried to obstruct the blood cir-
culation elsewhere in the body (See also
b lo o d c lo t t in g
t h r o m b o s is
. )
th ru s h
A common name for the fungal infec-
c a n d id ia s is
th u m b -s u c k in g
A common habit in young children,
w hich provides comfort, oral gratifica-
reassurance. Thumb-sucking
decrease after age three, and most chil-
dren grow out of it by age seven. In most
cases, it is not harmful. However,
m a lo c -
c lu s io n
permanent teeth may develop if the habit
continues past seven years of age. This
problem is usually temporary, but if the
thumb-sucking persists, an
o rt h o d o n t ic
a p p lia n c e
may be needed.
th y m o m a
A rare
t u m o u r
of the
th y m u s g la n d .
tumour can arise from any of the cell
types in the thymus gland and can be
cancerous or noncancerous. Thymoma
is associated with the autoimmune dis-
m y a s t h e n ia g r a v is
th y m o x a m in e
m o x is y ly t e
th y m u s g la n d
A gland that forms part of the
im m u n e
s y s t e m
The thymus gland lies behind
s te rn u m
(breastbone) and consists of
two lobes that join in front of the
tra c h e a
(windpipe). Each lobe of the thymus
gland is made of lymphoid tissue con-
ly m p h o c y te s
e p ith e liu m
(lining cells), and fat.
The thymus conditions lymphocytes
to become
T -c e lls
It plays a part in the
immune response until
p u b e r t y
ally enlarging during this time. After
puberty, it shrinks, but some glandular
tissue remains until middle-age.
th y ro g lo s s a l d is o rd e rs
A set of congenital defects caused by
failure of the thyroglossal duct to close
up during embryonic development. In
e m b r y o s
this duct runs from the base of
the tongue to the
t h y ro id g la n d
mal development may cause the duct to
persist in its entirety or partly as a cyst.
A cyst may become infected and swollen,
w hich may lead to formation of a
fis tu la
between the cyst and the surface of the
neck). The cyst and any remaining parts
of the duct are removed.
Thyroglossal duct and cyst
The thyroglossal duct, lying between the tongue
and the thyroid, sometimes persists after fetal life,
and a cyst may form at any point along the duct.
th y ro id c a n c e r
t u m o u rs
of the
t h y ro id g la n d .
although exposure to radioactive fallout
increases the risk of the condition.
There are several types, depending on
the cells involved. In all types, the first
sign is a firm nodule in the neck, w hich
may grow slowly or rapidly (however, a
not necessarily
cancer: about 10 per cent of thyroid
tumours are found to be cancerous). In
many cases, the cancer is painless and
symptoms such as difficulty swallow-
ing, and hoarseness or loss of voice,
only develop when the tumour presses
on other structures.
A diagnosis is made by
th y ro id s c a n n in g
n e e d le a s p ira tio n
or a
b io p s y
th y -
ro id e c t o m y
(surgical removal of thyroid
tissue) is usually followed by treatment
with radioactive
io d in e
to destroy any
residual cancer. Cure rates depend on
the cell type and on the size and spread
of the tumour when it is diagnosed.
Patients need to take the thyroid hor-
th y ro x in e
for the rest of their lives.
th y ro id e c to m y
Surgical removal of all or part of the
th y-
r o id g la n d
w hich is performed as a
treatment for
th y ro id c a n c e r
some cases
h y p e rt h y ro id is m
(overactivity of the
thyroid) and of
g o it re
(enlargement of
the thyroid), or a noncancerous tumour
of the thyroid gland.
th y ro id -fu n c tio n te s ts
A group of blood tests used to evaluate
the function of the
th y ro id g la n d
and to
diagnose under- or overactivity of the
gland. Tests may include measurement
of levels of the thyroid hormones T3 and
T4, as well as thyroid-stimulating hor-
mone (TSH), the
p it u it a ry g la n d
that stimulates the thyroid gland.
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