thyroid -SB

Question 1

What is the preferred initial test for evaluating thyroid function?

Answer 1

Thyroid-Stimulating Hormone (TSH).

Question 2

What is the relationship between small changes in T4 and the resulting changes in TSH called?

Answer 2

A log-linear relationship.

Question 3

High-dose supplementation with what vitamin can falsely lower TSH levels?

Answer 3

Biotin (5-10 mg/day).

Question 4

In patients with goiter and/or subclinical hypothyroidism, measuring _____ antibodies is useful for predicting the development of overt hypothyroidism.

Answer 4

Thyroid Peroxidase (TPO)

Question 5

What is the most common cause of hypothyroidism in the United States?

Answer 5

Hashimoto’s thyroiditis (Chronic Autoimmune Thyroiditis).

Question 6

What is the most common cause of hypothyroidism worldwide?

Answer 6

Iodine deficiency.

Question 7

What is the mechanism behind consumptive hypothyroidism?

Answer 7

Neoplastic tissues overexpress deiodinase type 3 (D3), leading to rapid inactivation of thyroid hormones T4 and T3.

Question 8

What is the typical full replacement dose of levothyroxine (L-T4) for overt primary hypothyroidism?

Answer 8

1.6 mcg/kg, ideally based on ideal body weight (IBW).

Question 9

How soon should TSH be rechecked after initiating levothyroxine therapy?

Answer 9

In 4-6 weeks.

Question 10

Why is TSH not a useful marker for monitoring levothyroxine therapy in central hypothyroidism?

Answer 10

TSH can be suppressed with small doses of L-T4, falsely suggesting over-replacement.

Question 11

What is the approximate half-life of T4 (levothyroxine)?

Answer 11

7 days.

Question 12

What is the approximate half-life of T3 (liothyronine)?

Answer 12

Approximately 22 hours.

Question 13

Why should T3-containing preparations be avoided during pregnancy for treating hypothyroidism?

Answer 13

Fetal neurodevelopment in early gestation depends on maternal free T4.

Question 14

What is the recommended IV loading dose of levothyroxine for a patient in myxedema coma?

Answer 14

200-400 µg IV.

Question 15

According to ATA/AACE guidelines, treatment for subclinical hypothyroidism is definitively recommended when the TSH level is greater than what value?

Answer 15

$>10$ mIU/L.

Question 16

A patient develops hyperthyroidism followed by hypothyroidism. This is a common side effect of which drug class?

Answer 16

Immune checkpoint inhibitors (e.g., anti-CTLA-4, anti-PD-1).

Question 17

Amiodarone-Induced Thyrotoxicosis (AIT) Type I is caused by unregulated thyroid hormone production and typically occurs in patients with what underlying condition?

Answer 17

A pre-existing abnormal thyroid gland (e.g., multinodular goiter or latent Graves’ disease).

Question 18

What is the first-line treatment for Amiodarone-Induced Thyrotoxicosis (AIT) Type II?

Answer 18

Prednisone (glucocorticoids).

Question 19

A patient presents with a painful, tender, and slightly enlarged thyroid, with pain radiating to the jaw. This clinical picture is characteristic of what condition?

Answer 19

Subacute thyroiditis.

Question 20

Riedel’s thyroiditis is characterized by infiltration of _____ in the thyroid and extensive fibrosis.

Answer 20

IgG4-positive plasma cells

Question 21

Which of the following sonographic features is associated with an increased risk of thyroid cancer: hyperechoic or hypoechoic?

Answer 21

Hypoechoic.

Question 22

What sonographic feature is described as punctate echogenic foci and is associated with a high risk of thyroid cancer?

Answer 22

Microcalcifications.

Question 23

According to the ACR TI-RADS classification, a nodule that is ‘taller-than-wide’ in shape receives how many points?

Answer 23

3 points.

Question 24

Under the ATA (2015) guidelines, what is the estimated risk of malignancy for a solid hypoechoic nodule with irregular margins and microcalcifications?

Answer 24

> 70 to 90% (High suspicion).

Question 25

What is the recommended FNA biopsy size cutoff for a 'low suspicion' thyroid nodule according to ATA (2015) guidelines?

Answer 25

> 1.5 cm.

Question 26

In the Bethesda system for reporting thyroid cytopathology, what is the diagnostic category for Class IV?

Answer 26

Follicular neoplasm or suspicious for a follicular neoplasm.

Question 27

What is the mean risk of malignancy for a Bethesda Class III (Atypia of undetermined significance) thyroid nodule?

Answer 27

16% (excluding NIFTP).

Question 28

What does the acronym NIFTP stand for?

Answer 28

Noninvasive Follicular Thyroid Neoplasm with Papillary-Like Nuclear Features.

Question 29

The reclassification of some encapsulated follicular variants of PTC to NIFTP was intended to prevent _____ for these indolent tumors.

Answer 29

overtreatment

Question 30

What type of genetic mutations are most commonly found in NIFTP tumors?

Answer 30

RAS mutations.

Question 31

Which aggressive genetic mutation is characteristically absent in NIFTP tumors?

Answer 31

BRAF V600E mutation.

Question 32

What is often considered a sufficient surgical treatment for a confirmed NIFTP tumor?

Answer 32

Lobectomy.

Question 33

According to the provided study, the introduction of an AI decision support system reclassified 80% of nodules initially classified as ACR-TIRADS 3 into what category?

Answer 33

A lower risk category.

Question 34

For a differentiated thyroid cancer tumor that is less than 1 cm without high-risk features, what is the preferred surgical procedure?

Answer 34

Thyroid lobectomy.

Question 35

A total thyroidectomy is recommended for differentiated thyroid cancer tumors that are greater than or equal to what size?

Answer 35

$\geq 4$ cm.

Question 36

For a patient with multifocal papillary microcarcinoma, what is the surgical recommendation if there are five or more foci?

Answer 36

Total thyroidectomy.

Question 37

According to ATA guidelines, radioactive iodine (RAI) is not routinely administered for remnant ablation in which risk group?

Answer 37

Low-risk patients.

Question 38

For which ATA risk group is postoperative radioactive iodine (RAI) ablation recommended?

Answer 38

High-risk patients.

Question 39

According to the ATA risk stratification system, what is the size cutoff for a metastatic lymph node to be considered high risk?

Answer 39

$\geq 3$ cm in largest dimension.

Question 40

In the AJCC 8th edition staging for differentiated thyroid cancer, what is the age cutoff that significantly alters the staging groups?

Answer 40

55 years.

Question 41

For a patient with an excellent response to therapy after total thyroidectomy and RAI ablation, what is the target nonstimulated thyroglobulin (Tg) level?

Answer 41

$<0.2$ ng/mL.

Question 42

A nonstimulated thyroglobulin (Tg) level greater than 30 ng/mL in a patient who underwent a lobectomy signifies what type of response to therapy?

Answer 42

Biochemical incomplete response.

Question 43

What is the recommended serum TSH goal during the first year of monitoring for a patient with high-risk differentiated thyroid cancer?

Answer 43

$<0.1$ mU/L.

Question 44

For a patient with an 'excellent' response to therapy, what is the ongoing TSH suppression goal?

Answer 44

0.5 to 2 mU/L.

Question 45

What is the sonographic appearance of a 'comet-tail artifact' indicative of?

Answer 45

A benign finding, typically representing colloid.

Question 46

During active surveillance of micropapillary thyroid cancer, surgery is recommended if the nodule increases in size by how much?

Answer 46

3 mm.

Question 47

A T3 to T4 ratio greater than 20 is more consistent with _____ than with thyroiditis.

Answer 47

Graves' disease

Question 48

In a patient with intermediate-risk differentiated thyroid cancer, what is the recommended TSH suppression target postoperatively?

Answer 48

0.1 to 0.5 mIU/L.

Question 49

Which two tyrosine kinase inhibitors (TKIs) are approved for advanced medullary thyroid cancer (MTC)?

Answer 49

Vandetanib (VAN) and Cabozantinib (CAB).

Question 50

Which two tyrosine kinase inhibitors (TKIs) are approved for advanced differentiated thyroid cancer (DTC)?

Answer 50

Sorafenib (SOAR) and Lenvatinib (LEN).

Question 51

How should a hypothyroid woman adjust her levothyroxine dose as soon as pregnancy is confirmed?

Answer 51

Increase the dosage by approximately 30% (e.g., taking two extra doses per week).

Question 52

What is the primary treatment for a toxic adenoma?

Answer 52

Thyroid lobectomy.

Question 53

A patient has a slightly elevated TSH (4.4), high free T4 (2.8), and a normal pituitary MRI. This presentation is most consistent with what diagnosis?

Answer 53

Thyroid Hormone Resistance (THR).

Question 54

In the differential diagnosis between a TSH-secreting pituitary adenoma and thyroid hormone resistance, an elevated serum alpha-subunit would favor which condition?

Answer 54

TSH-secreting pituitary adenoma (TSHoma).

Question 55

In euthyroid patients taking amiodarone, TSH is often in the _____-normal range.

Answer 55

high

Question 56

What is the specific indicator of thyrotoxicosis in a patient on amiodarone?

Answer 56

A suppressed TSH.

Question 57

In Sick Euthyroid Syndrome, which thyroid hormone level is usually the first to become low?

Answer 57

T3.

Question 58

In a patient with subclinical hyperthyroidism who is young, asymptomatic, and has a TSH of 0.2 mIU/L, what is the recommended management?

Answer 58

Recheck thyroid function tests in six months.

Question 59

A patient has a high total T4 but normal free T4, normal T3, and normal TSH. This pattern is characteristic of what condition?

Answer 59

Familial Dysalbuminemic Hyperthyroxinemia (FDH).

Question 60

What is the recommended management for a symptomatic substernal goiter?

Answer 60

Thyroidectomy via collar incision.

Question 61

A thyroid nodule FNA is Bethesda Class 4, and molecular analysis reveals a RET/PTC rearrangement. What is the recommended management?

Answer 61

Total thyroidectomy, due to the high risk of cancer.

Question 62

In a patient with thyrotoxicosis and low radioiodine uptake, what laboratory test helps differentiate between painless thyroiditis and factitious thyrotoxicosis?

Answer 62

Serum thyroglobulin (elevated in thyroiditis, low in factitious thyrotoxicosis).

Question 63

A patient with differentiated thyroid cancer has an 'indeterminate response' to therapy one year after treatment. What is the recommended management?

Answer 63

Repeat surveillance testing in one year.

Question 64

What is the presentation of anaplastic thyroid cancer?

Answer 64

A rapidly growing, firm neck mass, often with pain, in an older patient.

Question 65

In managing Graves' disease during pregnancy, the goal is to keep the maternal free T4 in what range?

Answer 65

In the high-normal to mildly elevated range.

Question 66

When converting a patient from oral to IV levothyroxine, what percentage of the oral dose should be administered intravenously?

Answer 66

50-75%.

Question 67

What is the definitive treatment for sight-threatening Graves' orbitopathy (e.g., ischemic neuropathy) that has failed high-dose steroid therapy?

Answer 67

Urgent orbital decompression surgery.

Question 68

HCG-induced thyrotoxicosis can be caused by germ cell tumors when HCG levels are significantly high, typically greater than what value?

Answer 68

$>$ 400,000 to 500,000 IU/L.

Question 69

Hürthle cell carcinoma is a distinct tumor type that is often refractory to what common therapy for differentiated thyroid cancer?

Answer 69

Radioiodine (RAI) therapy.

Question 70

In a patient with suspected panhypopituitarism and adrenal crisis, which hormone must be replaced first: hydrocortisone or levothyroxine?

Answer 70

Hydrocortisone must be administered first to prevent precipitating an adrenal crisis.

Question 71

Women who require RAI treatment for thyroid cancer should wait at least how long after treatment before attempting pregnancy?

Answer 71

At least six months.

Question 72

A patient on methimazole develops a fever and sore throat. What is the most immediate and critical next step?

Answer 72

Repeat the CBC with differential to check for agranulocytosis.

Question 73

If a patient's TSH remains elevated despite escalating doses of levothyroxine, and free T4 is rising, what should be suspected?

Answer 73

Heterophilic antibody interference (HAMA) causing a falsely elevated TSH.

Question 74

In a patient with new palpable 2 cm thyroid nodule with irregular margins and microcalcifications, what is the estimated risk of malignancy?

Answer 74

70-90%.

Question 75

What procedure can be used to diagnose metastatic thyroid cancer in a suspicious lymph node when the FNA cytology is negative but clinical suspicion is high?

Answer 75

Thyroglobulin washout of the FNA needle.

Question 76

For mild, active Graves' eye disease, besides local measures, what supplement may improve symptoms?

Answer 76

Selenium (100 micrograms twice daily).

Question 77

The presence of a PAX8/PPAR$\gamma$ rearrangement on molecular analysis of a thyroid nodule is indicative of what?

Answer 77

Malignancy, and referral for total thyroidectomy is recommended.

Question 78

What is the most congruent histologic diagnosis for a low-risk thyroid nodule with a RAS pathogenic variant on molecular testing?

Answer 78

Benign follicular adenoma.

Question 79

What is the effect of oral estrogen on thyroxine-binding globulin (TBG) and total T4 levels?

Answer 79

Oral estrogen increases TBG synthesis, which in turn increases total T4 levels.

Question 80

In a patient with medullary thyroid cancer and extensive metastatic disease, a sudden, dramatic drop in serum calcitonin levels may be due to what laboratory phenomenon?

Answer 80

The 'hook effect,' causing an artificially low measurement.

Question 81

What is a common adverse effect of high-dose radioactive iodine treatment on oral health?

Answer 81

Dental cavities due to salivary gland dysfunction.

Question 82

How should a fine-needle aspiration (FNA) biopsy of a high-suspicion thyroid nodule be managed in a pregnant patient during the first trimester?

Answer 82

The biopsy should be performed, as the nodule is assessed similarly to a non-pregnant patient.

Question 83

What X-linked genetic condition, caused by a defect in the MCT8 gene, presents with severe intellectual disability, spastic quadriplegia, and abnormal thyroid function tests (low T4, high T3)?

Answer 83

Allan-Herndon-Dudley Syndrome.

Question 84

RAI activity should be reduced by what percentage for patients with thyroid cancer and end-stage kidney disease?

Answer 84

0.5

Question 85

After exposure to iodinated contrast media, RAI administration should be deferred for at least how long?

Answer 85

At least 3 months.

Question 86

In a pregnant woman not on thyroid hormone, what is the next step if her first-trimester TSH is between 2.6 and 4.0 mU/L?

Answer 86

Measure TPO antibodies.

Question 87

What is the recommended initial daily dose of levothyroxine for a pregnant woman diagnosed with overt hypothyroidism?

Answer 87

A full replacement dose of 1.6 mcg/kg.

Question 88

For a patient with a Bethesda IV nodule, if genetic testing and a microRNA classifier are both negative, what is the appropriate follow-up?

Answer 88

Follow up with thyroid ultrasound in one year.

Question 89

Increasing thyroglobulin antibodies in a patient previously treated for papillary thyroid cancer are indicative of what?

Answer 89

Recurrent disease.

Question 90

A 45-year-old woman with hyperthyroidism has decreased radioiodine uptake in the neck but measurable serum thyroglobulin. A whole-body scan should be ordered to evaluate for what condition?

Answer 90

Struma ovarii.

Question 91

The genetic condition Pendred syndrome, which causes goiter and sensorineural deafness, is due to pathogenic variants in the _____ gene.

Answer 91

SLC26A4 (pendrin gene)

Question 92

Which benign tissue can sometimes cause false-positive radioactive iodine uptake on scans, particularly in patients with Graves' disease?

Answer 92

Thymic tissue.

Question 93

PTEN hamartoma tumor syndrome, also known as Cowden syndrome, is associated with an increased risk of thyroid cancer, breast cancer, and what type of gastrointestinal lesions?

Answer 93

Gastrointestinal hamartomas.

Question 94

What congenital birth defects are associated with methimazole use in the first trimester of pregnancy?

Answer 94

Aplasia cutis, choanal atresia, and esophageal atresia.