Thyroid
&
Parathyroid
Surgery
What is
the thyroid
gland?
The
thyroid
gland is a
butterfly
shaped organ
that resides
in the front
part of your
neck, just
in front of
your
windpipe and
below your
voice box.
The gland
normally
weighs one
ounce or
less. In
thin
individuals,
a portion of
the gland
may be
palpated
(felt with
the fingers)
through the
overlying
skin and
muscle in
the neck.
In very
muscular
individuals
or those
with
increased
amounts of
adipose
tissue, the
gland can be
difficult or
impossible
to feel with
the
fingertips.
It has a
very rich
blood
supply, and
is fed by
branches of
the
subclavian
and carotid
arteries.
The thyroid
gland rests
on top of
the nerves
which are
responsible
for moving
your vocal
cords. The
internal
thyroid
architecture
is composed
of multiple
spherical
groups of
cells
surrounding
a gelatinous
material
known as
colloid.
The
spherical
units are
known as
follicles.
Colloid is a
collection
of protein
bound to
thyroid
hormone.
The cells
forming the
colloid-containing
spheres
(follicles)
are called
follicular
cells.
These are
the most
abundant
cells in the
thyroid.
What does
the Thyroid
Gland do?
The
thyroid
gland
absorbs
iodine from
your blood
stream and
turns this
iodine into
thyroid
hormone.
Iodine is
found in
many foods
and enters
the body via
the
gastrointestinal
tract.
There are
two
important
types of
thyroid
hormone: T3
which
contains 3
iodide
(iodine)
molecules
and T4 which
contains 4
iodide
molecules.
The thyroid
gland
secretes
thyroid
hormone into
the
bloodstream
and the
hormone
circulates
throughout
the body.
Thyroid
hormone is
responsible
for your
body’s
metabolism
(breakdown
of molecules
to form
energy) and
certain
forms of
protein
synthesis.
Every cell
in the body
relies on
thyroid
hormone to
regulate its
metabolism.
If your
thyroid
gland is
overactive
(hyperthyroid)
and
secreting
too much
hormone, you
may
experience
rapid heart
rate,
palpitations,
weight loss,
anxiety and
heat
intolerance
(you always
feel warm).
If your
thyroid
gland is
underactive
(hypothyroid)
you may gain
weight,
become
lethargic,
suffer from
constipation
and have
cold
intolerance
(you always
feel cold).
Thyroid
Nodules
Thyroid
nodules are
relatively
common.
Clinical
studies show
that
ultrasound
can detect
thyroid
nodules in
20%-76% of
the general
population
[1,2].
Three
percent to
7% of the
population
has a nodule
that can be
palpated
(felt)
during a
routine
physical
examination
[3,4].
Solid
thyroid
nodules form
when one or
more cells
in the
thyroid
gland
deviate from
the normal
cell life
cycle and
engage in
unregulated
cell
division.
Some nodules
show steady
growth, many
become
stable in
size and
others
regress.
Most solid
nodules
produce less
thyroid
hormone than
the
surrounding
normal
thyroid
tissue.
These
nodules
appear
“cold” on a
thyroid
function
scan.
However,
some nodules
also display
unregulated
production
of thyroid
hormone.
These
nodules
appear “hot”
on a thyroid
function
scan. Hot
nodules can
cause
hyperthyroidism.
Sometimes
the nodules
form large
follicles
and contain
colloid
(colloid
nodule)-see
explanations
of
“follicle”
and
“colloid”
above in
“What is the
thyroid
gland?”
Nodules may
be solitary
or
associated
with other
nodules in
the gland.
An enlarged
thyroid
gland with
multiple
nodules is
called a
multinodular
goiter.
Very large
nodules or
multinodular
goiters may
cause an
obvious
cosmetic
deformity in
the neck,
difficulty
swallowing
or
compression
of the
trachea with
difficulty
breathing.
The vast
majority of
thyroid
nodules are
benign (not
cancerous).
About 1 in
20 thyroid
nodules are
cancerous.
Cancerous
nodules have
the ability
for the
abnormal
thyroid
cells to
invade into
the
surrounding
thyroid
tissue and
spread
beyond the
thyroid to
lymph nodes
and other
structures
in the
neck. In
rare
circumstances,
the lungs
and then
other parts
of the body
may be
invaded by
thyroid
cancer.
Certain
features are
associated
with an
increased
risk of
cancer in
thyroid
nodules: A
family
history of
papillary or
medullary
types of
thyroid
cancer, age
less than 20
or greater
than 70
years, male
gender,
history of
head and
neck
radiation as
a child
(this was
performed
for acne or
enlarged
tonsils
years ago),
an enlarging
or
non-mobile
nodule, and
associated
vocal cord
paralysis.
Unfortunately,
there is no
fail-safe
way to
distinguish
benign
nodules from
cancerous
nodules by
way of
physical
examination
or imaging
(ultrasound,
thyroid
scan, CT
scan or MRI).
Furthermore,
nodule size
is not
predictive
of
malignancy.
Fine
needle
aspiration
biopsy is a
useful test
to help
determine
malignancy
or increased
suspicion
for
malignancy
in a thyroid
nodule.
During this
test, the
skin
overlying
the thyroid
gland is
cleansed and
anesthetized
(usually
injected
with
lidocaine).
A small
needle is
passed
through the
skin and
underlying
soft tissue
and then
into the
thyroid
gland. The
needle
enters the
thyroid
nodule and
extracts
some
abnormal
cells. The
cells are
spread on to
a glass
slide and
analyzed by
a
pathologist.
If the
thyroid
nodule cells
are
malignant,
suspicious
for
malignancy,
or if
malignancy
cannot be
ruled out,
partial or
complete
removal of
the thyroid
gland may be
discussed.
Additional
treatment ,
such as
radioactive
iodine, may
be necessary
if thyroid
cancer is
present. If
the needle
biopsy
suggests a
benign
nodule then
observation
of the
nodule is
often
undertaken.
This is
accomplished
with follow
up
ultrasound
to evaluate
for interval
growth.
Significant
growth
between
ultrasounds
is
concerning
for
malignancy.
