Hyper and Hypo-Thyroidism Flashcards
Three types of thyroid hormones?
Thyroxine (T4) Triiodothryonine (T3) Reverse Triiodothryonine (rT3)
What thyroid hormone is produced the most?
T4 (90%)
What is the more potent thyroid hormone?
T3 (10x more)
In tissue, what turns T4 to T3?
5-deiodinase
Where are T3/T4 synthesized?
In the colloid of follicular cells
On what molecule are T3/T4 synthesized?
A large tyrosine-rich glycoprotein called thyroglobulin
How is iodide transported into the follicular cells?
Na/I cotransporter
What turns I- into I2?
Thyroid peroxidase
How is I2 conjugated onto tyrosine of thyroglobulin?
By thyroid peroxidase forming MIT and DIT
Thyroid peroxidase also couples MIT and DIT what do they form?
MIT + DIT = T3
DIT + DIT =T4
Where is iodinated thyroglobulin stored?
In the colloid of the follicular cells
What occurs to T4?
It is activated to more potent T3 in target cells
Where does T3 bind?
To both an extracellular and an intracellular receptor
5 physiologic effects of thyroid hormone?
Growth CNS development Skeletal/Cardiac muscle Central sympathetic nervous stimulation Upregulates lipid, carbohydrate, oxidative metabolism, protein synthesis
What are the four thyroid replacement drugs?
Levothyroxine (drug of choice)
Liothyronine
Liotrix
Desiccated thyroid
What is Levothyroxine?
T4
What is Liotrix?
T3 + T4
What is Liothyronine?
T3
What is desiccated thyroid?
Porcine thyroid
What is a potential SE of desiccated thyroid?
Antibodies forming against the porcine
What are the drug overdose SE of thyroid replacement drugs?
High sympathetic tone
What test can Liothyronine used for?
TSH suppression test
What are the 5 classes of anti-thyroid drugs?
Radioactive iodides Anion inhibitors Beta blockers Iodides Thioamides
What are the radioactive iodides?
131 I
