Let’s diagnose hypothyroidism.
Free T4 will be low in all forms.
TSH will be increased only in what kind of
Anti-thyroglobulin or anti-thyroperoxidase
are huge markers so that you can perhaps identify
and diagnose a patient with Hashimoto.
Hypothalamic and pituitary disease, tell me
what these are respectively?
You would call hypothalamic hypothyroidism
- tertiary; you will call pituitary hypothyroidism
In both of these instances, you would expect
your TSH levels to be decreased.
Now, that first bullet point should make perfect
sense that no matter what the cause of your
hypothyroidism, by definition, you have free
T4 in all forms.
Hypothyroidism… synthetic thyroxine is treatment
of choice, right?
In other words, synthroid.
Replacement dose typically, well, the dosage
is here, you may take a look at it as you
Start a full dose in a young patient, however
as it get older, you want to be careful as
to how much synthroid that you give, please.
Typically requires a dose increase when pregnant
or taking oestrogen, why?
If your patient presenting with hypothyroidism,
you’re giving them thyroxine T4; patient
pregnant oestrogen increased thyroid binding
globulin, it is going to then rob or attach
the free T4, therefore the administration
of your synthroid that you’ve given initially
is pretty much ineffective or has decreased
effectiveness, doesn’t it?
Increase your dosage, that you want to know.
Adjust the T4 of replacement dose… well,
here, once again, if you want to take a look
at the dosage, you may do so in your own time;
adjust those every six to eight weeks because
you’re worried about… now, the half-life
is important for you to know of approximately
You’re monitoring this patient just about
as often as you can.
Treatment, well, specific situations… subclinical
hypothyroidism… controversial, we’ll let
Consider treating however if your patient
has anti-thyroperoxidase given higher rate
of progression to overt hypothyroidism.
Overt meaning what?
We’re going from subclinical into actual
clinical so that becomes very important to
The auto antibodies towards your peroxidase
or perhaps your thyroglobulin.
Huh, situation here… not good, myxoedema
You do everything in your power to slow this
Treatment includes IV T4, IV T3 and stress dose glucocorticoids
Stress dose glucocorticoid coverage often
times that you find a patient with myxoedema
coma is in a very, very highly stressful state.
So, therefore, you were thinking about and
very, very likely give him glucocorticoids.
If no improvement at this point, you have
no choice but to give this patient emergent
Hypothyroidism will make fever, tachy response
to infection, lots of stress taking place;
consider treating if positive for anti-thyroperoxidase
given, once again, you’re worried about
this patient go... given or going into overt
Myxoedema coma is critical.
This table here is going to give you a summary
of all, I repeat, all real quick hyper and
Primary hypothyroidism examples such as Graves’.
We had a full discussion about radioactive
iodine uptake previously.
If you haven’t looked at it or if you are
confused, this would be a good time to make
sure that you’re perfectly clear about when
you would have an increase or decrease with
radioactive iodine uptake.
If it’s primary increased free T4, decreased
TSH; if it’s secondary hyperthyroidism an
increase in TSH, increase in free T4, this
would be a tumour that’s functioning in
the anterior pituitary releasing too much
Now, the topic at hand in this discussion
If it’s primary such as Hashimoto, you have
a decrease in free T4, an increase in TSH.
I wish to repeat here just one more time,
this is where students keep missing is, is
that in primary, not only do you have an increase
in TSH, you also have an increase in TRH,
thus you have hyperprolactinemia.
Do not ever forget that.
In secondary hypothyroidism, the problem is
Anterior pituitary specifically.
Anterior pituitary insufficiency is a topic
that we have had in the very beginning of
endocrinology where examples such as apoplexy
and infarction and a non-functioning adenoma
were all part… all differentials of pituitary
insufficiency resulting in secondary hypothyroidism
with decreased TSH and decreased free T4.