Thyroid

Question 1

What are the three thyroid hormones?

Answer 1

Triiodothyronine (T3)
Tetraiodothyronine (T4, thyroxine)
Calcitonin

Question 2

What is a Calcitonin?

Answer 2

A Ca+2 regulatory hormone- decreases plasma calcium concentration by incorporating it into the bone and increasing elimination in the kidneys

Question 3

Which thyroid hormone is more potent?

Answer 3

Triiodothyronine (T3) is more potent than T4

Question 4

Which hormone is inactive?

Answer 4

Reverse T3 (rT3)

Question 5

Which hormone is active and how does it become this way?

Answer 5

T4 gets converted intracellularly to T3, which is the active hormone

Question 6

What is released from the hypothalmus and causes the release of TSH?

Answer 6

TRH

Question 7

What is released from the anterior pituitary and stimulates production of T3 and T4?

Answer 7

TSH

Question 8

How does Iodide get transported into the thyroid follicle epithelial cells intially?

Answer 8

By the Na+/I- symporter in the basement membrane

Question 9

What inhibits Iodide transportation by Na+/I-?

Answer 9

SCN, TcO4, ClO4

Question 10

What transports Iodide in the apical membrane?

Answer 10

Pendrin- which is also found in the cochlea of the inner ear

Question 11

What does Pendrin deficiency cause?

Answer 11

Deafness and Goiter (hypothyroidism) (Pendred’s Syndrome)

Question 12

What converts Iodide into Iodine?

Answer 12

Thyroidal peroxidase

Question 13

What is thyroidal peroxidase blocked by?

Answer 13

High Iodide levels and thioamide drugs

Question 14

After converting Iodide into Iodine, Thyroidal peroxidase then does what?

Answer 14

Iodinates tyrosine residues in thyroglobulin to form mono-iodotyrosine (MIT) & di-iodotyrosine (DIT)

Question 15

The process of Thyroidal peroxidase conversion of iodide to iodine, and tyrosine to MIT & DIT is called:

Answer 15

Iodide Organification

Question 16

MIT and DIT combine and form what?

Answer 16

combination of T3 and two DIT, which then forms T4

Question 17

T4 and T3 are released how?

Answer 17

By proteolytic cleavage of thyroglobulin and exocytosis.

Question 18

High Iodide inhibits what?

Answer 18

Proteolysis of thryoglobulin, inhibiting T3/T4 release

Question 19

What are T3 and T4 bound to in the plasma?

Answer 19

TBG

Question 20

What removes the outer ring of Iodide and what does it form?

Answer 20

5’ deiodinase removes the ring and forms active T3 (3,5,3’ triiodothyronine)

Question 21

Removal of the INNER ring of Iodide gives what?

Answer 21

inactive reverse T3

Question 22

Hypothyroidism is marked by what?

Answer 22

Elevated TSH levels and low free T4 and T3

Question 23

Hypothyroidism is cased by:

Answer 23

1) Hashimoto’s thyroiditis (autoimmune disease)
2) Congenital (cretinism in children)
3) Radiation
4) 131 Iodide
5) Thyroidectomy
6) Dis-hormogenesis
7) Drug Induced- Amiodarone, Ipodate
8) Iodine Deficiency

Question 24

Hyperthyroidism is caused by:

Answer 24

1) Grave’s Disease (autoimmune)
2) Toxic uninodular goiter and multinodular goiter
3) Subacute thyroiditis
4) Thyroid Storm (acute)

Question 25

List the thyroid preparations:

Answer 25

1) Synthetic | 2) Animal Origin

Question 26

Synthetic thyroid preparations of T4 are:

Answer 26

Levothyroxine (T4)- DOC**** - generic - Synthroid - Levoxyl - Levo-T - Levothyroid - Levolet - Novothyrox - Unithroid

Question 27

Synthetic thyroid preparations of T3 are:

Answer 27

Liothyronine (T3) - generic - Cytomel - Triostat

Question 28

What drug has a combo of T4 & T3?

Answer 28

Thyrolar (Liotrix) (4:1 T4:T3)

Question 29

Animal origin prep'd thyroid:

Answer 29

Dessicated thyroid - generic - Armour Thyroid - Thyroid Strong - Thyrar

Question 30

Anti-thyroid agents are...

Answer 30

``` Thioamides Anion Inhibitors Iodides Iodinated contrast media Radioactive Iodine B-adrenoceptor blocking drug ```

Question 31

Examples of Thioamide anti-thyroid agents are:

Answer 31

Methimazole (Tapazole) Propylthiouracil (generic) **Used for thyro-toxicosis**

Question 32

Anti-thyroid agents are used for:

Answer 32

thyro-toxicosis

Question 33

What inhibits Iodide transport mechanism?

Answer 33

Anion inhibitors: - Perchlorate (ClO4 2-) - Pertechnate (TcO4 2-) - Thiocyanate (SCN-)

Question 34

Methimazole MOA:

Answer 34

inhibits Iodine organification

Question 35

Iodides are rarely...

Answer 35

used as sole therapy

Question 36

Examples of Iodinated contrast media anti-thyroid agents are:

Answer 36

Diatrizoate (Hypaque) | Iohexol (Omnipaque)

Question 37

What is useful in treating thyro-toxicosis by preventing conversion of T4 to T3?

Answer 37

Iodinated contrast media anti-thyroid agents: - Diatrizoate (Hypaque) - Iohexol (Omnipaque)

Question 38

Examples of Radioactive Iodine anti-thyroid agents are:

Answer 38

131 Iodine (radioiodine)

Question 39

131 Iodine is C/I'd in:

Answer 39

pregnancy and nursing mothers

Question 40

Examples of B-adrenoceptor blocking drug anti-thyroid agents are:

Answer 40

Metoprolol Propranolol Atenolol

Question 41

What is a goiter?

Answer 41

An enlarged thyroid gland

Question 42

What is used to treat HYPOthyroidism?

Answer 42

replacement therapy: | levothyroxine, liothyronine, dessicated thyroid

Question 43

What do you monitor when treating hypothyroidism?

Answer 43

TSH levels

Question 44

Elderly patients with CAD often develop:

Answer 44

Myxedema (severe hypothyroidism- swelling of the affected area)

Question 45

Thyroxine treatment in Elderly patients with CAD can cause

Answer 45

arrhythmia, MI, angina pectoris

Question 46

Myxedema coma is what?

Answer 46

And end stage untreated hypothyroidism and is a MEDICAL EMERGENCY that must be carefully managed in the ICU

Question 47

Hypothyroidism may result in:

Answer 47

anovulation

Question 48

Fetal brain development depends on:

Answer 48

maternal T4 that gets through the placenta, therefore hypothyroid in pregnant women must be carefully managed

Question 49

Subclinical hypothyroidism is what?

Answer 49

A high TSH with a normal thyroid hormone level

Question 50

Subclinical hypothyroidism requires what treatment?

Answer 50

T4 or monitored carefully

Question 51

What drugs can induce hypothyroidism?

Answer 51

Amiodarone (Iodide (I-) containing molecule)

Question 52

Hyperthyroidism is also known as:

Answer 52

thyrotoxicosis

Question 53

What is Grave's Disease and it's MOA?

Answer 53

autoimmune disease: autoantibodies bind TSH receptors in the thyroid and stimulate release of the thyroid hormone.

Question 54

How do you manage Grave's Disease?

Answer 54

Anti-thyroid Drugs, surgical thyroidectomy, and treatment with Radioiodine (131 I)

Question 55

Anti-thyroid drug therapy is treatment with:

Answer 55

methimazole/ propylthiouracil

Question 56

Propylthiouracil vs. Methimazole:

Answer 56

Propylthiouracil is highly protein bound and less likely to cross the placenta- so could be used in pregnancy, whereas Methimazole cannont be used in pregnancy

Question 57

Radioiodine (131 I) does what?

Answer 57

It is a B emitter and gets concentrated in the thyroid and destroys the thyroid cells.

Question 58

When taking 131 I, what must be avoided?

Answer 58

Iodides, in order to maximize uptake of 131 I

Question 59

What hyperthyroidism treatments are C/I'd in Pregnancy?

Answer 59

Methimazole and 131 I

Question 60

Beta adrenergic therapy is used in hyperthyroidism as...

Answer 60

adjunct therapy

Question 61

Neonatal Grave's Disease is caused by:

Answer 61

maternal anti-TSHR autoantibodies and is self-limiting (otherwise needs management)

Question 62

Amiodarone may cause...

Answer 62

hyperthyroidism

Question 63

Hyperthyroidism Type I is due to:

Answer 63

Increased levels of T3 and T4

Question 64

Hyperthyroidism Type I is treated with:

Answer 64

Thioamides

Question 65

Hyperthyroidism Type II is treated with:

Answer 65

Glucocorticoids

Question 66

Hyperthyroidism Type II is due to:

Answer 66

inflammatory damage to gland causing increased release of hormone

Question 67

Nontoxic goiters are caused by:

Answer 67

iodine deficiency

Question 68

How do you treat nontoxic goiters?

Answer 68

Iodine supplements (potassium iodide KI)

Question 69

Thyroid neoplasm (tumor) is treated:

Answer 69

Radioactive treatment following thyroidectomy and lifelong treatment with levothyroxine