Part 1

Question 1

What is T3 and its main source?

Answer 1

Triiodothyronine (T3); main source is peripheral deiodination

10% is derived from direct thyroidal secretion

Question 2

What percentage of thyroid hormone physiological effects are due to T3 binding to receptors?

Answer 2

More than 90%

Question 3

What is the effect of ionic/anion inhibitors on thyroid hormone production?

Answer 3

Decreases the active transport of iodine into the thyroid, leading to a reduction in thyroid hormone production

Question 4

What condition is associated with the use of Guanethidine eye-drops?

Answer 4

Decreased Exophthalmos

Question 5

What role do glucocorticoids play in hyperthyroid states?

Answer 5

Protect against adrenal insufficiency and relieve thyroid pain and tenderness

Question 6

What is a contraindication for beta-blockers?

Answer 6

Decompensated heart failure unless caused solely by tachycardia

Question 7

What is the effective dosage range of beta-blockers for adrenergic symptoms?

Answer 7

20 to 40 mg four times daily

Question 8

What is the use of radioactive iodine (RAI) in hyperthyroidism?

Answer 8

Ablates thyroid tissue by emitting rays and particles

Question 9

What is the agent of choice for Graves’ disease?

Answer 9

Sodium iodide 131 (131I)

Question 10

What should be given prophylactically to patients receiving 131I?

Answer 10

Laxatives

Question 11

What is the initial dosage of Propylthiouracil for hypothyroidism?

Answer 11

200-400 mg in divided dosages until euthyroid state

Question 12

What are two causes of primary hypothyroidism?

Answer 12

• Autoimmune (Hashimoto’s disease)
• Iatrogenic (surgery or 131I)

Question 13

What is the average daily adult replacement dose of Levothyroxine (L-T4)?

Answer 13

112 mcg given as a single dose

Question 14

What are the goals of therapy for hypothyroidism?

Answer 14

• Restore normal thyroid hormone in tissue
• Provide symptomatic relief
• Prevent neurologic deficits in newborns and children
• Reverse biochemical abnormalities associated with hypothyroidism

Question 15

What are the symptoms of hypothyroidism?

Answer 15

• Tiredness
• Weakness
• Sexual dysfunction
• Dry skin
• Hair loss
• Difficulty concentrating
• Muscle cramps
• Menorrhagia and infertility in women

Question 16

What is the drug of choice for hyperthyroidism?

Answer 16

Carbimazole

Question 17

Fill in the blank: The role of thioamides is based on _______ hormone synthesis.

Answer 17

[decrease in iodination of tyrosine residues]

Question 18

What is the effect of thyroid hormones on the cardiovascular system in hyperthyroidism?

Answer 18

Increases heart rate and myocardial strength

Question 19

What condition causes excessive levels of T4 or T3 in tissues?

Answer 19

Hyperthyroidism (Thyrotoxicosis)

Question 20

What are common symptoms of hyperthyroidism?

Answer 20

• Hyperactivity
• Irritability
• Heat intolerance
• Palpitations
• Weight loss with increased appetite

Question 21

What is the treatment approach for reducing thyroid hormone synthesis?

Answer 21

• Antithyroid drugs
• Ionic/Anion inhibitors
• Radioiodine (131I)
• Surgery

Question 22

What is gynecomastia?

Answer 22

Enlargement of breast tissue in males

This condition can be caused by hormonal imbalances, medications, or certain health conditions.

Question 23

What is exophthalmos?

Answer 23

Protrusion of the eyeballs

Often associated with hyperthyroidism, particularly Graves’ disease.

Question 24

What does pretibial myxedema refer to?

Answer 24

Thickening of the skin on the shins

This condition can occur in patients with thyroid disease, especially hyperthyroidism.

Question 25

What is the first approach to treating hyperthyroidism?

Answer 25

Reducing thyroid hormone synthesis ## Footnote This can be achieved through antithyroid drugs, ionic/anion inhibitors, radioiodine, or surgery.

Question 26

Name three antithyroid drugs.

Answer 26

* Propylthiouracil * Carbimazole * Methimazole (thiamazole) ## Footnote These drugs help reduce the synthesis of thyroid hormones.

Question 27

What is the role of propranolol in hyperthyroidism treatment?

Answer 27

To relieve symptoms by reducing thyroid hormone effects ## Footnote Propranolol is a beta-blocker that helps manage symptoms such as rapid heartbeat.

Question 28

What is the Wolf-Chaikoff effect?

Answer 28

Reduction in synthesis of thyroxin due to large doses of iodide ## Footnote This phenomenon can temporarily inhibit thyroid hormone production.

Question 29

What are the desired outcomes of hyperthyroidism therapy?

Answer 29

* Eliminate excess thyroid hormone * Minimize symptoms and long-term consequences ## Footnote Effective management aims to restore normal thyroid function and improve quality of life.

Question 30

What factors influence individualized therapy for hyperthyroidism?

Answer 30

* Type and severity of hyperthyroidism * Patient age and gender * Existence of non-thyroidal conditions * Response to previous therapy ## Footnote Tailoring treatment to the individual patient is critical for effective management.

Question 31

What does a suppressed radioactive iodine uptake (RAIU) indicate?

Answer 31

Inflammation or thyroiditis reflecting thyrotoxicosis ## Footnote This suggests an excess of thyroid hormones due to the release of preformed stores.

Question 32

What is the normal level of TSH?

Answer 32

Practically excludes abnormality ## Footnote Abnormal elevated TSH levels signify hypothyroidism.

Question 33

What is the initial recommended dose of L-T4 for cretinism therapy?

Answer 33

10–15 µg/kg daily ## Footnote This helps rapidly normalize serum T4 concentration.

Question 34

How is levothyroxine sodium used in adult hypothyroidism?

Answer 34

* 50 µg/day for 2 weeks * 100 µg/day for 2 weeks * 150 µg/day for life ## Footnote This gradual increase helps achieve optimal thyroid hormone levels.

Question 35

What is the strength of Liothyronine sodium compared to T4?

Answer 35

Stronger than T4 (4 times more potent) ## Footnote It has a quicker onset but shorter duration of action.

Question 36

What is the significance of T4 in thyroid hormone synthesis?

Answer 36

It is the most important source of T3 by peripheral tissue deiodination ## Footnote T4 is converted to T3, the most active thyroid hormone.

Question 37

What is the feedback mechanism regulating thyroxine release?

Answer 37

Involves hypothalamic-pituitary axis ## Footnote TSH from the anterior pituitary regulates thyroxine release, which is influenced by TRH from the hypothalamus.

Question 38

What are the three types of hormones synthesized by the thyroid gland?

Answer 38

* Thyroxine (T4) * Tri-iodothyronine (T3) * Thyrocalcitonin (Calcitonin) ## Footnote Each hormone plays a distinct role in metabolism and calcium regulation.

Question 39

What is the primary treatment for thyroid cancer following surgical removal?

Answer 39

L-T4 therapy to suppress TSH stimulation ## Footnote This helps prevent the growth of differentiated thyroid cancers.

Question 40

What is the prevalence of lithium-induced hypothyroidism in patients taking lithium?

Answer 40

Occurs in 20-30% of patients ## Footnote Lithium can inhibit T3 and T4 secretion and is associated with goiter.

Question 41

What is the impact of amiodarone on thyroid function?

Answer 41

Can induce hyperthyroidism in 3% of patients ## Footnote Amiodarone has a high iodine content and may cause abnormal thyroid function tests.

Question 42

What is the most sensitive test for diagnosing thyroid disorders?

Answer 42

Serum TSH ## Footnote It is also the best test to evaluate treatment results in thyroid disorders.