Endo_Test 1: Maloney_Thyroid Pharmacology

Front 1

47-year-old female presents at her family practice physician complaining of fatigue and chronic constipation. She states that she is always cold and has gained 10 lbs in the last 4 months, even though she has not had much of an appetite. Physical exam revealed dry skin, nonpitting edema in her lower extremities, a somewhat puffy face, and a slightly enlarged thyroid. A test was positive for thyroid peroxidase antibodies. What would you most likely see on her lab test?

Back 1

↓T3, ↓T4

This is Hashimoto's (anti-TPO)
**HYPOthyroidism**

Front 2

Hashimotos and Radiation cause ____thyroidism

Back 2

hypothyroidism

Front 3

What are possible treatment options for primary hypothyroidism (eg. from Hashimoto’s thyroiditis)?

Back 3

Give T3, T4

Front 4

What is primary hypothyroidism?

Back 4

There is a failure of the thyroid to produce sufficient thyroid hormone

Front 5

What is secondary/tertiary hypothyroidism?

Back 5

Diminished stimulation of thyroid by TSH d/t:

hypothalmic disease (tertiary)

pituitary disease (secondary)

Front 6

What are possible treatment options for secondary hypothyroidism (eg from pituitary dysfunction)?

Back 6

Give T3, T4

Front 7

What are the synthetic thyroid hormone preparations?

Back 7

Levothyroxine (T4)

Liothyronine (T3)

Front 8

Which synthetic Thyroid Hormone drug is mainly used?

Back 8

Levothyroxine (T4)

Front 9

Clinical Use:

- Hypothyroidism

-TSH suppression therapy in patients with thyroid cancer

- Occasionally those with nontoxic goiter

Back 9

Mainly Levothyroxine (T4)

Front 10

Why would you use levothyroxine in a euthyroid patient with a nontoxic goiter?

Back 10

There is a decreased release of TSH from pituitary

Decrease the growth and size of the goiter

Front 11

MOA: Levothyroxine in treating a nontoxic goiter

Back 11

Blocks TSH from pituitary

Reduces size and growth of tumor

reduces TH released

Front 12

What might you expect to see when treating a nontoxic goiter with levothyroxine?

Back 12

Hyperthyroidism

(you are giving synthetic TH while the patient is still producing human TH)

Front 13

Why is levothyroxine (T4) preferred over liothyronine (T3) for hormone replacement therapy?

Back 13

T4 is converted to T3

T4 has the longest half-life

Front 14

When might you want
to use liothyronine (T3) ?

Back 14

An emergency such as MYXEDEMA COMA.

T3 would work much faster to reverse hypothyroidism

Front 15

A 37-year-old female presents to your clinic for unintentional weight loss. Over the past 3 months, she
has lost approximately 15 lb without changing her diet or
activity level. Otherwise, she feels great. She has an
excellent appetite, no gastrointestinal complaints except for occasional loose stools, a good energy level, and no complaints of fatigue. She denies heat or cold
intolerance. Her heart rate is 108 bpm, blood pressure
142/82 mm Hg, and she is afebrile. When she looks at
you, she seems to stare, and her eyes are somewhat
protuberant. You note a large, smooth, nontender
thyroid gland, and her skin is warm and dry. There is a
fine resting tremor. She most likely has:

A. Diffuse (simple) goiter
B. Graves’ disease
C.Hashimoto’s thyroiditis
D.Myxedema
E. Toxic multinodular goiter

Back 15

Graves’ disease

(Auto-antibodies to TSH receptor)

Front 16

A 37-year-old female presents to your clinic for unintentional weight loss. Over the past 3 months, she
has lost approximately 15 lb without changing her diet or
activity level. Otherwise, she feels great. She has an
excellent appetite, no gastrointestinal complaints except for occasional loose stools, a good energy level, and no complaints of fatigue. She denies heat or cold
intolerance. Her heart rate is 108 bpm, blood pressure
142/82 mm Hg, and she is afebrile. When she looks at
you, she seems to stare, and her eyes are somewhat
protuberant. You note a large, smooth, nontender
thyroid gland, and her skin is warm and dry. There is a
fine resting tremor.

You determine she has Grave's Disease

Propanolol would be useful in treating which of her symptoms?

Back 16

**Tremor**
blocks β2 on muscle

**Tacchycardia**
blocks β1 on heart

**HTN**

Front 17

How could you treat a patient's hyperthyroidism who is diagnosed with Grave's Dz?

A. Inhibit thyroid hormone synthesis

B. Inhibit thyroidhormone release

C. Inhibit the thyroid hormone receptor

D. Destroy thyroid tissue

Back 17

A. Inhibit thyroid hormone synthesis

B. Inhibit thyroidhormone release

D. Destroy thyroid tissue

Front 18

**Antithyroid Agents**

______ → inhibit synthesis

______ → inhibit synthesis/release

______ → Destroy Tissue

Back 18

Front 19

Name the Drug Class:

Methimazole

Propylthiouracil

Back 19

Thioamides

(Inhibit TH synthesis)

Front 20

MOA: Thioamides for hyperthyroidism

Back 20

Inhibit thyroid peroxidase (TPO) from forming T3, T4

Front 21

What enzyme catalyzes the reaction between iodide, H2O2 and TG to form MIT and DIT, and the coupling reaction between MIT and DIT to form T3 and T4?

Back 21

Thyroid Peroxidase

Front 22

What enzyme is involved in the
conversion of T4 to T3 in peripheral tissue?

Back 22

Thyroid Hormone Deiodinase

Front 23

Which thioamide partially inhibits the peripheral deiodination of T4 to T3?

Back 23

Propylthiouracil

Front 24

MOA:

Inhibits thyroid peroxidase (TPO)-catalyzed reactions thereby blocking iodine organification (production of MIT, DIT) and iodotyrosine coupling (production of T3, T4).

- This decreases thyroid hormone synthesis

Back 24

Methimazole

Propylthiouracil

(Thioamides)

Front 25

Clinical Use:

- Control hyperthyroidism while waiting for spontaneous remission from Grave's Disease

- Control hyperthyroidism before radioactive iodine or surgical treatment

Back 25

Methimazole

Propylthiouracil

(Thioamides)

Front 26

How quickly will methimazole cause a patient with Graves’hyperthyroidism to become euthyroid?

Back 26

A few weeks

You have stored TH and it will take a few weeks to get rid of the stored stuff

Front 27

Which theoamide agent causes a more rapid achievement of euthyroidism?

Back 27

Methimazole

Front 28

Which thioamide is teratogenic, ESPECIALLY during the first trimester during organogenesis?

Back 28

Methimazole

Front 29

Which thioamide causes hepatotoxicity and liver failure?

Back 29

Prophylthiouracil

Front 30

Which agent is first line for the treatment of hyperthyroidism?

Back 30

Methimazole

(No hepatotoxicity side effects)

Front 31

Which agent would you use for hyperthyroidism during pregnancy?

A. Methimazole throughout

B. Propylthiouracil throughout

C. 1st – Methimazole 2nd, 3rd – Propylthiouracil

D. 1st – Propylthiouracil
2nd, 3rd – Methimazole

Back 31

D. 1st – Propylthiouracil
2nd, 3rd – Methimazole

(Remember, Methimazole is teratogenic during the first trimester)

Front 32

Lugol’s solution = ________

Back 32

Iodide Salts (potassium idodide [SSKI])

Front 33

What is 131^I- ?

Back 33

Radioactive iodine

Front 34

What is the difference in using
high levels of iodide salts and
radioactive iodine to treat
hyperthyroidism?

***

Back 34

**Iodide salts**
the effect is REVERSIBLE and transient. Improvement is seen within 2-7 days but limited to several weeks.

**Radioactive Iodine**
the effect is PERMANENT.
Usually takes several weeks to restore thyroid hormone levels to ‘normal’.

Front 35

Clinical Use:

Destroy some of the thyroid tissue

Back 35

Radioactive iodine

Front 36

Treatment algorithm for hyperthyroidism

Back 36

Front 37

Adverse Effects:

Skin rash
Pruritus
Arthralgias
Fever
Nausea
Agranulocytosis - rare

Back 37

Thioamides

Front 38

What is the biggest
side effect of radioactive iodine?

Back 38

Hypothyroidism if you destroy too much tissue

Front 39

What are the absolute contraindications to Radioactive Iodine?

Back 39

- Pregnancy, lactation

- Inability to comply with radiation safety regulations

Front 40

You are giving a patient methimazole for graves disease and want to add a drug for preoperative treatment. What should you give them?

Back 40

**Iodide Salts**

- Decrease vascularity, size and fragility of the hyperplastic thyroid

- Lower serum thyroid hormone concentrations in patients that are not euthyroid

Front 41

Should iodide salts be used before and/or after radioactive iodine?

Back 41

ONLY AFTER

Giving large doses of iodine before radiation would cause competition at the symporter and neither would get in the colloid space

Front 42

Which anti-thyroid drugs treat thyroid storm? Which are the quickest?

Back 42

Iodide salts (rapid: 2-7 days)

Thioamides

Front 43

An acute, life-threatening, hypermetabolic state induced by excessive release of thyroid hormones (THs) in individuals with thyrotoxicosis.

The clinical presentation includes fever, tachycardia, hypertension, and neurological and GI abnormalities. Hypertension may be followed by congestive heart failure that is associated with hypotension and shock

Back 43

Thyroid Storm

Front 44

What could you use to treat a
thyroid storm?

A. Levothyroxine
B. Methimazole
C. Iodide salts
D. Propranolol
E. Propylthiouracil
F. Radioactive iodine

Back 44

B. Methimazole
C. Iodide salts
D. Propranolol
E. Propylthiouracil

Front 45

Why are iodide salts given at least an hour after a thioamide in a patient with a
thyroid storm?

A. Iodine will block the uptake of thioamides into the thyroid gland

B. The thioamide will
prevent the iodine from
being used as a substrate for new thyroid hormone synthesis

Back 45

The thioamide will prevent the iodine from being used as a substrate for new thyroid hormone synthesis

Front 46

What may be an advantage of using propylthiouracil vs methimazole in a patient with a thyroid storm?

Back 46

Blocks the conversion of T4 to T3 peripherally

More rapid reduction in serum T3 levels