Thyroid

Question 1

Embryologic origin of thyroid?

Answer 1

Endodermal cells of foramen cecum

Question 2

What may persist during descent of thyroid tissue

Answer 2

pyramidal lobe

Question 3

If the thyroglossal duct doesn’t close what can happen

Answer 3

Thyroglossal duct cyst

Question 4

What are the C cells origin?

Answer 4

4th pharyngeal pouch

Neural crest tissue

Question 5

What is the blood supply of the thyroid gland?

Answer 5

Superior thyroid

Inferior thyroid

Question 6

What is the anatomic location of the superior thyroid artery?

Answer 6

1st branch of external carotid, runs with superior laryngeal nerve.

Question 7

What is the anatomic location of the inferior thyroid artery?

Answer 7

Branch off thyrocervical trunk, runs with recurrent laryngeal nerve
Provides blood supply to all 4 parathyroid glands
50% of the time passes ant, 50% passes post to recurrent laryngeal

Question 8

What provides blood supply to all 4 parathyroid glands

Answer 8

Inferior thyroid artery

Question 9

What is the anatomic location of the thyroid IMA?

Answer 9

Rises off of inominate

5% of people

Question 10

Venous drainage of thyroid gland?

Answer 10

Superior/Middle Drain into internal jugular

Inferior drains into inominate(bracheocephalic)

Question 11

Hyperthyroidism tx?

Answer 11

1st medical therapy
PTU, Methimazole: Agranulocytosis, aplastic anemia

PTU okay for pregnancy
Methimazole causes cretinism in pregnancy

Question 12

Graves Disease pathophys?

Answer 12

Autoimmune dz caused by Ab to TSH -> hyperthyroid

Question 13

What does graves look like on scintigraphy?

Answer 13

Diffuse uptake of entire thyroid gland

Question 14

Grave Disease tx?

Answer 14

1st medical management
PTU, Methimazole, beta blocker

2nd
Radioactive ablation

3rd - Surgical tx
Thyroidectomy

Question 15

If grave’s needs thyroidectomy what is important to do pre-op?

Answer 15

Must be euthyroid
Beta blocked + Lugol’s solution 14 days prior to surgery
To avoid thyroid storm

Question 16

Toxic multinodular goiter - pathophys

Answer 16

Prolonged low grade TSH stimulation - cause

Question 17

Toxic multinodular goiter Tx

Answer 17

Total or subtotal lobectomy

because iodine ablation doesn’t work as well

Question 18

Hyper-Thyroid workup

Answer 18

1st: TSH
If low then think hyperthyroid
2: US w/ FNA

Question 19

Hashimoto’s thyroiditis pathophy, s/s, treatment?

Answer 19

Chronic lymphocytic thyroiditis
Anti thyroid antibodies
Enlarged painless thyroid
Tx: Tyroid replacement

Question 20

Dequervian’s (subacute granulomatosis thyroiditis) pathophy, s/s, treatment?

Answer 20

Viral etiology
Painful
Elevated ESR
Dec radioiodine uptake
Tx: Pain control, beta blockers, steroids

Question 21

Palpable thyroid nodule workup

Answer 21

5% turn out to be malignant

H/P: Hx of radiation, FHx of thyroid and endocrine cancers

Labs: TSH

Imaging: US - hypoechogenicity, microcalcification, irregular margins, lymphatic invasion

Thyroid scintigraphy: Distinguish btw solitary toxic adenoma and graves disease with cold nodules

FNA Biopsy: Solid hypoechoic nodule > 10 mm

Question 22

Bethesda Criteria

Answer 22

6 possibilites, if discordinant with imaging repeat biopsy.

Repeat FNA if non diagnostic, Follicular cells of undetermined significance;

Just due lobectomy if follicular neoplasms;

If suspicious for malignancy do lobectomy w/ frozen section to see if you need to do a total

1: Non diagnostic - repeat FNA
2: Benign - Okay
3: Follicular of undetermined sig - repeat FNA
4: Follicular neoplasm - lobectomy
5: Suspicious of malignancy - lobectomy with frozen
6: Malignant - Total thyroidectomy

Question 23

Papillary CA - MC cancer

Answer 23

Hx: irradiation to neck
Epidemiology: Women
s/s: Palpable lymph nodes, rare mets
Local invasion affects prognosis
Path: Orphan annie nuclei -> White circle, cleared out nuclei
Tx: Total thyroidectomy - b/c 3 benefits - Removal of potential multifocal disease, preparation of post op radioiodine therapy, able to use thyroglobulin for surveillance

Question 24

What if with papillary CA identify + nodes, biopsy of nodes shows thyroid tissue, or intraop have + nodes

Answer 24

Tx: Total thyroidectomy, expand dissection (include level 6), removal of nodes in section where nodes are posititve

Question 25

Adjuvant therapy?

Answer 25

Adjuvant radioactive iodine when TSH elevated ->4-6 weeks post op Hold exogenous thyroid hormone (levothyroxine - because long half life), or give a recombinant TSH b/c shorter half life post op

Question 26

Follicular thyroid CA

Answer 26

Hematogenous spread Rare lymph spread Hurthle cells - more aggressive follicular Tx: Total thyroidectomy after lobectomy for diagnosis, w/ radioactive iodine ablation Modified radical neck dissection (if positive nodes)

Question 27

Medullary thyroid CA

Answer 27

Parafollicular C cells - neural crest origin, 4th pharyngeal pouch Produces calcitonin - if > 400 then higher likelihood of mets Radioactive iodine is ineffective 50% secretes CEA 20% germline mutations in RET proto-oncogene (MEN, familial thyroid cancer) 80% sporadic Tx: Total thyroidectomy w/ central node dissection if - nodes Total thyroidectomy w/ central and lateral node dissection if + nodes (levels 2-6) Surveillance: Measure calcitonin and CEA levels q 6 months for 1 year, then annually afterwards

Question 28

Central node dissection

Answer 28

level 6

Question 29

Lateral node dissection

Answer 29

Levels 2-5

Question 30

Anatomic variation - non recurrent R laryngeal nerve

Answer 30

Arteria lucoria: Aberrant R subclavian artery

Question 31

How to avoid injury to superior laryngeal nerve

Answer 31

Ligate superior pole vessels close to thyroid

Question 32

Monitor for surveillance

Answer 32

Total thyroglobulin

Question 33

Most active thyroid hormone

Answer 33

T3

Question 34

Where is T3 most produced?

Answer 34

Peripherally with deiodinase

Question 35

Midline mass moves up and down with patient swallowing?

Answer 35

Thyroglossal duct cyst- Remanant of foramen cecum | Tx: Resect cyst with mid point of hyoid bone, b/c of small risk of malignant regeneration and risk of infection

Question 36

What causes fever, tachycardia, HTN post op in pt with Graves?

Answer 36

Thyroid storm Did not pre-op with beta blockade, PTU, lugols Tx: Cooling blankets, beta blockade, PTU, lugols, O2

Question 37

Elevated calcitonin most common symptom?

Answer 37

Diarrhea

Question 38

MEN 2A when is prophylactic thyroidectomy

Answer 38

6 y.o

Question 39

MEN 2B when is prophylactic thyroidectomy

Answer 39

< 2 y.o.

Question 40

Likelihood of thyroid cancer in a kid < 14 w/ thyroid nodule

Answer 40

50% | Most commonly papillary cancer

Question 41

Acute suppurative thyroiditis most common organisms

Answer 41

Staph aureus | Strep pyogenes

Question 42

Acute suppurative thyroiditis presentation

Answer 42

Tender, fluctuant goiter, Inc WBC, normal thyroid function tests, age 20-40 y.o.

Question 43

Acute suppurative thyroiditis diagnosis

Answer 43

Imaging - US | FNA -> Gram stain and culture

Question 44

Acute suppurative thyroiditis treatment

Answer 44

IV abx | If pyriform sinus fistula or abscess then surgical drainage

Question 45

Non tender asymptomatic thyroid nodule w/o adenopathy workup

Answer 45

US FNA (scintigraphy not useful, it is useful if the person is hyperthyroid and you want to know if hot or cold nodule)

Question 46

Malignant US findings

Answer 46

``` Heterogeneous Hypoechoic Microcalcifications Hypervascular Cervical Adenopathy ```

Question 47

Treatment for nodule in Men > 60

Answer 47

Excision Risk of cancer goes from 12 -> 70% from age 60->70 in men. Men at higher risk for nodule being cancer, women at higher risk for having a nodule Cold nodule more likely to be cancerous.

Question 48

Myxedema coma presentation

Answer 48

hypothyroidism; hypocortisolemia; hypoventilation, often requiring intubation; hypothermia; hyponatremia; hypotension; hypoglycemia; and infection. Insulin administration would be inappropriate in the setting of hypoglycemia.