When to start hypothyroidism treatment
Hypothyroidism and Hashimoto's Thyroiditis: Visual Explanation for Students
hi this is tom from zero to finals calm
in this video I'm going to be talking
about hypothyroidism you can find
written notes on this topic at zero da
finals comm slash hypothyroidism or in
the endocrinology section of the zero to
finals Medicine book let's jump straight
in hyperthyroidism is the term used to
describe inadequate output of thyroid
hormones by the thyroid gland there's a
few different causes the most common
cause of hyperthyroidism in the
developed world is Hashimoto's
thyroiditis and this is caused by
autoimmune inflammation of the thyroid
gland so the body's immune system
attacking the thyroid gland it's
associated with anti-thyroid peroxidase
or anti TPO antibodies and also with
anti thyroid globulin antibodies
initially it causes a bit of a goiter
after which there's atrophy of the
thyroid gland as the hyperthyroidism
sets in iodine deficiency is the most
common cause of hyperthyroidism in the
developing world and this is because
iodine is essential for the production
of thyroid hormones iodine is added to
foods like table salt to prevent iodine
deficiency and to prevent hypothyroidism
hyperthyroidism can also occur as a
result of treatment for hyperthyroidism
so all the treatments for
hyperthyroidism have the potential to
overshoot and cause hypothyroidism so
these are treatments like kaboom azole
propath io uracil radioactive iodine and
of course thyroid surgery there are also
medications that can cause
hyperthyroidism lithium inhibits the
production of thyroid hormones in the
thyroid gland and so can cause a goiter
and hypothyroidism amiodarone interferes
with the thyroid hormone production and
metabolism and usually it causes a
hyperthyroidism
but it can also cause a thorough
toxicosis there's also secondary causes
of hyperthyroidism or central causes and
this is where the pituitary gland is
failing to produce enough TSH and this
is often associated with a lack of other
pituitary hormones as well such as ACTH
and this is called hypopituitarism and
it has quite a few different causes and
these causes can be tumors of the
pituitary gland infections in that area
vascular pathology such as something
called Sheehan syndrome where you get
pituitary necrosis
after massive blood loss during child
and radiation therapy to the pituitary
gland so how do patients with
hypothyroidism present well they can
present with weight gain fatigue dry
skin coarse hair and hair loss they can
have fluid retention so they can develop
a Deemer or pleural effusions or ascites
they can have amenorrhea so the periods
stop and it can slow down the bowels and
make the very constipated so when you
suspect hypothyroidism how do you
investigate them well firstly you would
do a TSH find that the TSH is abnormal
and then do t3 and t4 levels in primary
hypothyroidism this is caused by a
thyroid gland insufficiency so the
thyroid hormones like t3 and t4 will be
low and the TSH level will be high
because there's no negative feedback to
the pituitary gland
so the Petrucci produces lots of TSH to
try and get the thyroid working again in
secondary hypothyroidism it's caused by
pituitary pathology and that results in
a low production of TSH
so TSH will be low and the thyroid
hormones will be low how do we manage
hypothyroidism
well it's quite straightforward we
simply replace the thyroid hormone that
isn't there with oral lever thyroxine so
we give them oral thyroid hormone in the
form of levothyroxine levothyroxine is
synthetic t4 and it metabolizes in the
body to t3 so you get t4 and t3 from
this one medication the doses are
titrated until TSH levels are normal so
when you start lever thyroxine initially
measure the TSH levels monthly until the
TSH level is stable and then once stable
it can be checked less frequently unless
the patient becomes symptomatic so if
the TSH level is high you know the dose
of levothyroxine is too low so it needs
to be increased and if the TSH level is
low you know that the dose of
levothyroxine is too high and it needs
to be reduced
so thanks for watching I hope you found
this video helpful if you did don't
forget there's plenty of other resources
on the zero to finals website including
loads and loads of notes on various
different topics that you might cover in
medical school with specially made
illustrations there's also a whole test
section where you can find loads of
questions to test your knowledge and see
where you're up to in preparation for
your exams
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I'll see you again soon
