Thyroid Overview and Cancer

Question 1

Functions of Thyroid Gland

Answer 1

• hormonal regulation
• secretes thyroid hormone
• homeostasis of metabolic processes

Question 2

Anatomy of Thyroid Gland

Answer 2

• 2 lobes on either side of trachea (R larger)
• isthmus
• swallowing = upward movement

Question 3

What is the HPA Axis?

Answer 3

hypothalamus –> anterior pituitary –> thyroid gland

• TRH is released by hypothalamus to anterior pituitary
• TSH is released by pituitary to thyroid gland
• thyroid gland releases thyroid hormone T3 (negative feedback to hypothal and pituitary)

Question 4

What type of rhythm does TSH have?

Answer 4

diurnal: highest at night, but has long half life

Question 5

What stimulates thyroid hormone production?

Answer 5

• TSH exposure

- other: medication interference, etc

Question 6

What is required for thyroid hormone production?

Answer 6

• requires thyroglobulin
• iodine and tyrosine combine to form mono and di-iodotyrosines
• these couple 3 or 4 to make iodothyronines

Question 7

Thyroxine/T4

Answer 7

• coupling of two DIT
• 80% production in thyroid
• converted to T3 in tissues

Question 8

Triiodothyronine/T3

Answer 8

• coupling of DIT and MIT
• 20% production in thyroid
• most active form

Question 9

Normal TSH Range

Answer 9

0.4-4.8 mIU/mL

Question 10

Normal Total T3

Answer 10

80-200 ng/dL

Question 11

Normal Total T4

Answer 11

4.5-10.9 ng/dL

Question 12

Normal Free T4

Answer 12

0.8-1.7 ng/dL

Question 13

What might be the findings for anti-TG or anti-TPO testing?

Answer 13

antibody is abnormal = present in autoimmune diseases

Question 14

What are examples of local compression findings in thyroid disorders?

Answer 14

• dysphagia
• dyspnea
• hoarseness
• cervical pain

Question 15

Does a thyroid disorder typically present with pain?

Answer 15

no - very few will have tender thyroid (think subacute thyroiditis)

Question 16

What is the most common endocrine cancer?

Answer 16

thyroid cancer

Question 17

How is thyroid cancer diagnosed?

Answer 17

find needle aspiration biopsy

Question 18

What is the most common type of thyroid cancer?

Answer 18

papillary carcinoma = 80% of all thyroid cancer

Question 19

Papillary Carcinoma

Answer 19

• mets to nodes are common at dx
• 40-80 years
• long term survival/cure excellent

Question 20

Follicular Carcinoma

Answer 20

• well-differentiated
• 45-80 years
• commonly silent
• mets to nodes only 10% –> more common to find spread to bone, brain, lung

Question 21

Medullary Carcinoma

Answer 21

• <10% of thyroid cancers
• increases calcitonin levels
• genetic predisposition
• 20-50 years
• symptomatic: dysphagia, pressure

Question 22

Anaplastic Carcinoma

Answer 22

• highly aggressive, 1% of thyroid CA
• prevalent in goiter populations
• 60-80 years
• most are symptomatic: pain, dysphonia, dysphagia, dyspnea
• no cure: fatal w/in year

Question 23

Thyroid Lymphoma

Answer 23

• rapidly growing neck mass
• dysphagia, pain, dyspnea
• prognosis depends on stage 5-89% survival

Question 24

Thyroid CA Tx

Answer 24

• surgery for most
• after surg, radioactive iodine treatment for most
• goal is complete TSH suppression

Question 25

What is thyroid US used for?

Answer 25

• to visualize thyroid nodules and cysts

- aids in biopsy

Question 26

What is fine needle aspiration biopsy used for?

Answer 26

-to exclude malignancy

Question 27

What is radioactive iodine uptake scan used for?

Answer 27

• iodine absorption is evaluated

- does NOT treat or kill

Question 28

What is the difference between a hot and cold nodule in RAIU scans?

Answer 28

• hot = increased I uptake = benign

- cold = decreased uptake = possible cancer

Question 29

Sxs of Hyperparathyroid

Answer 29

• depression
• fatigue
• loss of appetite
• constipation, kidney stones
• osteoporosis, fractures

Question 30

Sxs of Hypoparathyroid

Answer 30

• painful spasms of face, hands, arms and feet

- seizures