We’re gonna be talking about thyroid emergencies,
how you recognize this and treat it in the Emergency Department.
So let’s start out by talking about what the thyroid does.
So the thyroid is located anterior to the trachea and the neck.
It’s a bilobular structure and it secretes two hormones.
So it secretes T3, 20% directly from the thyroid, the remainder is from T4 conversion.
And then it secretes T4 which is a pro-hormone.
So of the hormone that’s secreted 99.5% of that hormone,
so a big large percentage of it is bound to thyroxine binding globulin or TBG.
And it’s important to remember that only free T4 and T3 are metabolically active,
so it’s only about 4.5% of what the thyroid hormone secretes initially is free and metabolically active.
Now thyroid hormone affects cellular basal metabolic rate,
protein synthesis and growth and development.
So whenever you have abnormal levels of these thyroid hormones,
you’re gonna get your basal metabolic rate affected,
protein synthesis and possibly growth and development
and we’ll see that reflected along this lecture based on the symptoms
that people have when they have both hyperthyroid and hypothyroid.
So the thyroid hormone like many hormones in our body exist via a negative feedback loop.
So thyroid hormone production is first regulated by the thalamus and the pituitary gland.
So the hypothalamus stimulates thyroid releasing hormone
which then goes to the pituitary gland which secretes TSH
and then TSH stimulates production and release of T4 thyroxine and triiodothyronine—
I’m not gonna say that anymore for the rest of the lecture—T3 from the thyroid gland.
So once it’s released, T4 and T3 then have negative feedback mechanisms
on production of TRH and TSH.
The other thing that happens in the peripheral tissues,
T4 gets converted to T3 because T4 is a pro-hormone.