ATA hyperthyoidism guidelines

Question 1

What biochemical profile defines overt hyperthyroidism?

Answer 1

A low or undetectable serum TSH level with an elevated serum free thyroxine (FT4) and/or triiodothyronine (T3) level.

Question 2

How is subclinical hyperthyroidism defined biochemically?

Answer 2

A low or undetectable serum TSH level with normal serum free thyroxine (FT4) and triiodothyronine (T3) levels.

Question 3

In a patient with overt hyperthyroidism, the presence of what antibody is highly specific for Graves’ disease?

Answer 3

Thyrotropin receptor antibodies (TRAb), including thyroid-stimulating immunoglobulins (TSI).

Question 4

A patient with hyperthyroidism has a low radioactive iodine uptake (RAIU). What is the likely etiology?

Answer 4

Thyroiditis or exogenous thyroid hormone intake.

Question 5

What are the three definitive treatment options for Graves’ disease?

Answer 5

Radioactive iodine ($^{131}$I) therapy, antithyroid drugs (ATDs), and thyroidectomy.

Question 6

Which antithyroid drug is preferred for most non-pregnant patients with Graves’ disease due to its longer half-life and better safety profile?

Answer 6

Methimazole (MMI).

Question 7

During which specific period is propylthiouracil (PTU) the preferred antithyroid drug?

Answer 7

The first trimester of pregnancy.

Question 8

What is the primary mechanism of action of thionamides like methimazole and propylthiouracil?

Answer 8

They inhibit thyroid peroxidase (TPO), thereby blocking the organification and coupling steps of thyroid hormone synthesis.

Question 9

Propylthiouracil (PTU) has an additional mechanism of action not shared by methimazole. What is it?

Answer 9

It inhibits the peripheral conversion of T4 to the more active T3.

Question 10

What is the most severe, though rare, idiosyncratic reaction to thionamide therapy?

Answer 10

Agranulocytosis (absolute neutrophil count < 500/mm$^3$).

Question 11

What critical instruction must be given to every patient starting a thionamide regarding the risk of agranulocytosis?

Answer 11

To stop the medication immediately and obtain a complete blood count if they develop a fever or sore throat.

Question 12

Propylthiouracil carries a black box warning for what severe adverse effect?

Answer 12

Severe liver injury and acute liver failure.

Question 13

Why is methimazole avoided in the first trimester of pregnancy?

Answer 13

It is associated with a specific pattern of birth defects known as methimazole embryopathy, including aplasia cutis and choanal atresia.

Question 14

What is the therapeutic goal for free T4 levels when treating a pregnant patient with Graves’ disease?

Answer 14

To maintain the maternal free T4 at or just above the upper limit of the pregnancy-specific normal range using the lowest possible ATD dose.

Question 15

The use of _____ should be strongly considered for persistent subclinical hyperthyroidism (TSH < 0.1 mIU/L) in patients over 65 years old.

Answer 15

treatment (with RAI or ATDs)

Question 16

In the management of thyroid storm, when should iodide therapy (e.g., SSKI) be administered relative to thionamides?

Answer 16

At least one hour after the administration of a thionamide to prevent the iodide from being used as substrate for new hormone synthesis (Wolff-Chaikoff effect).

Question 17

What is the most significant modifiable risk factor for the development and progression of Graves’ orbitopathy (thyroid eye disease)?

Answer 17

Cigarette smoking.

Question 18

Radioactive iodine ($^{131}$I) therapy is absolutely contraindicated in which two patient populations?

Answer 18

Pregnant and breastfeeding women.

Question 19

What prophylactic medication should be considered in patients with risk factors for Graves’ orbitopathy who are undergoing radioactive iodine therapy?

Answer 19

Glucocorticoids (e.g., prednisone).

Question 20

What preoperative regimen is typically used to prepare a patient with Graves’ disease for thyroidectomy?

Answer 20

Pretreatment with methimazole to achieve euthyroidism, followed by 7-10 days of saturated solution of potassium iodide (SSKI) to decrease thyroid gland vascularity.

Question 21

A patient on methimazole develops arthralgias and a rash. Laboratory testing reveals a positive p-ANCA. What is the diagnosis?

Answer 21

ANCA-associated vasculitis, a rare but serious side effect of thionamide therapy.

Question 22

A hyperthyroid patient has a thyroid scan showing a single ‘hot’ nodule with suppression of the remaining thyroid tissue. What is the most likely diagnosis?

Answer 22

Toxic adenoma.

Question 23

What is the definitive treatment of choice for a solitary toxic adenoma or toxic multinodular goiter?

Answer 23

Radioactive iodine ($^{131}$I) therapy or surgery.

Question 24

When monitoring a patient on antithyroid drugs for Graves’ disease, how often should TSH and free T4 be checked after initiating therapy?

Answer 24

Every 4-6 weeks until the patient is euthyroid and the dose is stable.

Question 25

What is the typical duration of a course of antithyroid drug therapy for Graves' disease before considering remission?

Answer 25

Approximately 12 to 18 months.

Question 26

What is the most useful predictor of long-term remission after a course of antithyroid drug therapy for Graves' disease?

Answer 26

The normalization or disappearance of TRAb levels.

Question 27

In a patient with amiodarone-induced thyrotoxicosis (AIT), how can Type 1 be distinguished from Type 2?

Answer 27

Type 1 (iodine-induced) has increased vascularity on color flow Doppler and may have a positive RAIU if iodine stores permit, while Type 2 (destructive thyroiditis) has absent vascularity and low RAIU.

Question 28

What is the primary treatment for Amiodarone-Induced Thyrotoxicosis Type 2 (AIT-2)?

Answer 28

Glucocorticoids, such as prednisone.

Question 29

A patient presents with a tender thyroid gland, fever, and symptoms of hyperthyroidism following a viral URI. What is the most likely diagnosis?

Answer 29

Subacute (de Quervain's) thyroiditis.

Question 30

What is the primary treatment for the pain associated with subacute thyroiditis?

Answer 30

Nonsteroidal anti-inflammatory drugs (NSAIDs) or, in severe cases, glucocorticoids.

Question 31

What is the primary role of beta-blockers in the management of hyperthyroidism?

Answer 31

To control adrenergic symptoms such as palpitations, tremor, and anxiety.

Question 32

Which beta-blocker is often preferred in severe hyperthyroidism or thyroid storm due to its additional effect of inhibiting peripheral T4 to T3 conversion?

Answer 32

Propranolol.

Question 33

In patients with overt hyperthyroidism (TSH < 0.1), there is an increased risk of what specific cardiac arrhythmia?

Answer 33

Atrial fibrillation.

Question 34

Postpartum thyroiditis typically presents with a transient _____ phase followed by a _____ phase.

Answer 34

thyrotoxic; hypothyroid

Question 35

What is the recommended management of hyperthyroidism in a breastfeeding woman?

Answer 35

Low-dose methimazole (up to 20 mg/day) or propylthiouracil (up to 300 mg/day), with the infant's thyroid function monitored periodically.

Question 36

What are the two major potential complications of thyroidectomy for Graves' disease?

Answer 36

Recurrent laryngeal nerve injury and permanent hypoparathyroidism.

Question 37

In a patient with Graves' disease, what physical exam finding is most indicative of active, inflammatory orbitopathy?

Answer 37

Conjunctival injection, chemosis (edema), or periorbital edema.

Question 38

What is the first-line treatment for moderate-to-severe and active Graves' orbitopathy?

Answer 38

High-dose intravenous glucocorticoids.

Question 39

The monoclonal antibody _____ targets the IGF-1 receptor and is approved for the treatment of Thyroid Eye Disease.

Answer 39

Teprotumumab

Question 40

A TSH-secreting pituitary adenoma causes what type of hyperthyroidism?

Answer 40

Secondary hyperthyroidism (characterized by an inappropriately normal or high TSH in the setting of elevated FT4/T3).

Question 41

What is the term for hyperthyroidism caused by a struma ovarii?

Answer 41

Ectopic hyperthyroidism, where thyroid hormone is produced by thyroid tissue within an ovarian teratoma.

Question 42

What laboratory test can help differentiate a TSH-secreting pituitary adenoma from thyroid hormone resistance syndrome?

Answer 42

The alpha-subunit to TSH molar ratio, which is typically elevated (>1.0) in TSH-secreting adenomas.

Question 43

Treatment for persistent subclinical hyperthyroidism (TSH < 0.1 mIU/L) should be considered in postmenopausal women for what reason?

Answer 43

To reduce the risk of osteoporosis and fractures.

Question 44

What is Jod-Basedow phenomenon?

Answer 44

Iodine-induced hyperthyroidism, typically occurring in patients with underlying autonomous thyroid nodules or multinodular goiter after exposure to a large iodine load.

Question 45

What class of medication is contraindicated in the initial management of hyperthyroidism due to thyroiditis?

Answer 45

Antithyroid drugs (MMI, PTU), as the hyperthyroidism is due to release of pre-formed hormone, not new synthesis.

Question 46

A patient with painless (silent) thyroiditis is at an increased risk of developing what long-term thyroid condition?

Answer 46

Permanent hypothyroidism.

Question 47

What is apathetic hyperthyroidism?

Answer 47

A presentation of hyperthyroidism, typically in the elderly, characterized by blunted symptoms like lethargy, depression, and weight loss, rather than classic hyperactivity.

Question 48

In patients treated with radioactive iodine for Graves' disease, what is the most common long-term outcome?

Answer 48

Permanent hypothyroidism, requiring lifelong levothyroxine replacement.

Question 49

How does hydatidiform mole cause hyperthyroidism?

Answer 49

The molar pregnancy produces extremely high levels of human chorionic gonadotropin (hCG), which has weak TSH-like activity and can stimulate the TSH receptor.