Chapter 2 - Thyroid

Question 1

Disorder characterized by defective organification of iodine, goiter and sensorineural deafness

Answer 1

Pendred syndrome

Question 2

What are the 5 factors that alter thyroid function in pregnancy?

Answer 2

1) Inc HCG (stimulates TSH-r)
2) Inc TBG (via estrogen)
3) altered immune system
4) Inc thyroid hormone metabolism (placenta)
5) Inc urinary iodide excretion

Question 3

What hormones can suppress TSH secretions?

Answer 3

Dopamine
Glucocorticoids
Somatostatin

Question 4

The most useful physiologic marker of thyroid hormone action?

Answer 4

TSH

Question 5

Most common cause of diffuse nontoxic goiter worldwide?

Answer 5

Iodine deficiency

Question 6

Most common malignancy of the endocrine system?

Answer 6

Thyroid carcinoma

Question 7

Well differentiated thyroid ca

Answer 7

Papillary

Follicular

Question 8

Undifferentiated thyroid ca

Answer 8

Anaplastic

Question 9

What is the marker used in surveillance for:
A) Papillary and follicular Ca
B) Medullary Ca

Answer 9

A) Thyroglobulin

B) Calcitonin

Question 10

Most common type of thyroid cancer?

Answer 10

Papillary Ca

Pathology: psammoma bodies, orphan annie nuclei
Spread: lymphatic, capsule invasion

Question 11

What are the poor prognostic features of follicular thyroid ca?

Answer 11

1) Distant mets
2) >50 yo
3) >4cm size
4) Hurthle cell histology
5) Marked vascular invasion

Question 12

Goal TSH level prior to starting RAI?

Answer 12

> 25 mIu/L

Question 13

In hypothyroidism, after determining elevated TSH levels, the next step is to…?

Answer 13

Measure unbound T4

Question 14

Elevated TSH, normal T4 but with present TPO antibodies and symptoms–do we treat with T4?

Answer 14

Yes

If TPO antibodies are negative and no symptoms, subject the patient to annual follow up

Question 15

TRUE OR FALSE

Primary hypothyroidism is defined as elevated TSH, decreased T4

Answer 15

True

Present TPO antibodies determine an autoimmune cause and should be treated with T4

Question 16

TRUE OR FALSE

In patients with normal TSH levels, low unbound T4, it would be prudent to rule out drug effects, sick euthyroid syndrome and evaluate for anterior pituitary disease

Answer 16

True

Question 17

In evaluating thyroid nodules, the next step after receiving a NORMAL or ELEVATED TSH is?

Answer 17

Ultrasound
FNAB
Non diagnostic–repeat FNAB–if still non-diagnostic, close ff up or surgery
Malignant–pre op UTZ then surgery

Question 18

In evaluating thyroid nodules, the next step after receiving a DECREASED TSH is?

Answer 18

Radionuclide scanning

Nonfunctioning nodule–UTZ
Hyperfunctioning nodule–manage as hyperthyroid

Question 19

What is the protein precursor of thyroid hormones?

Answer 19

Thyroglobulin

Question 20

Major positive regulator of TSH

Answer 20

TRH

Question 21

What is the recommended average daily intake of iodine for specific populations?

Answer 21

Adults: 150-250mg/day
Children: 90-120mg/day
Pregnant/Lactating: 250mg/day

Question 22

Most common cause of neonatal hypothyroidism?

Answer 22

Thyroid gland dysgenesis

Question 23

Serum thyroglobulin levels are increased in all types of thyrotoxicosis except in where?

Answer 23

Thyrotoxicosis factitia

Question 24

Autoantibodies that stimulate TSH-R in Graves disease?

Answer 24

TSI

Question 25

Increased antibodies in autoimmune thyroid disease?

Answer 25

TPO

Question 26

Effect of estrogen on: A) TBG B) Free hormones level

Answer 26

A) Inc TBG | B) Normal (Total hormones are elevated)

Question 27

Sign illicited when arms are raised and it causes venous neck distention and difficulty breathing? Common in retrosternal goiters.

Answer 27

Pemberton's sign

Question 28

Method of choice to determine thyroid size accurately

Answer 28

Ultrasound

Question 29

Insidious painless goiter with symptoms due to compression?

Answer 29

Riedel's thyroiditis

Question 30

Treatment of subacute thyroiditis

Answer 30

Aspirin 600mg q4-q6 NSAIDS Prednisone 40-60mg

Question 31

Treatment of thyroid storm

Answer 31

PTU 500-1000mg loading then 250mg q4 SSKI 5 drops q6 Propranolol 60-80mg q4 Hydrocortisone 300mg IV bolus then 100mg q8

Question 32

Hormone pattern in sick euthyroid syndrome

Answer 32

Low total and unbound T3 Normal T4 and TSH Due to impaired T4 to T3 conversion

Question 33

What are the 2 major forms of amiodarone induced thyrotoxicosis?

Answer 33

Type I - with underlying thyroid abnormality with excessive thyroid hormone synthesis (Jod-Basedow phenomenon) Type II - no underlying thyroid abnormality; drug induced lysosomal activation leading to destructive thyroiditis with histiocyte accumulation

Question 34

Phenomenon when excess iodide transiently inhibits thyroid iodide organification?

Answer 34

Wolff-Chaikoff effect

Question 35

Dosing if methimazole and PTU?

Answer 35

Methimazole 10-20mg q8-12 | PTU 100-200mg q6-8

Question 36

Condition in the elderly wherein thyrotoxicosis may be subtle or masked?

Answer 36

Apathetic thyrotoxicosis

Question 37

Most common cause of thyrotoxicosis?

Answer 37

Grave's disease

Question 38

Difference between thyrotoxicosis and hyperthyroidism?

Answer 38

Thyrotoxicosis - state of hormone excess Hyperthyroidism - result of excessive thyroid function

Question 39

Daily replacement dose of levothyroxine?

Answer 39

1.6

Question 40

Dose of levothyroxine in starting treatment for subclinical hypothyroidism?

Answer 40

35-50 microgram/cl Goal is to normalize TSH

Question 41

Pathophysiology of myxedema in hypothyroidism

Answer 41

Increased dermal glycosaminoglycan content traps water

Question 42

Disease wherein there is a marked lymphocytic infiltration of the thyroid with germinal center formation, atrophy of the follicles?

Answer 42

Hashimoto's thyroiditis