Path 6 Thyroid

Question 1

C cells

Answer 1

Neuroendocrine parafollicular cells that secrete calcitonin

Question 2

Calcitonin function (4)

Answer 2

• Inhibit intestinal Ca absorption
• Inhibit renal tubular Ca reabsorption
• Inhibit bone osteoclast activity
• Inhibit renal phosphate reabsorption

Question 3

Thyroid regulation

Answer 3

++ Thyrotropin (TSH)

Question 4

Thyroid follicular cell function

Answer 4

Convert thyroglobulin into Thyroxine (T4) and Triiodothyronine (T3)

Question 5

T3 and T4 in plasma

Answer 5

Bound to transthyretin

Question 6

T3 and T4 in cells

Answer 6

Binds to nuclear receptors -> TREs (thyroid hormone response elements) in nucleus

Question 7

2 congenital thyroid malformation

Answer 7

• Thyroglossal duct cyst

- Lingual thyroid

Question 8

Hyperthyroidism cell effects

Answer 8

Mediated by T3

• Increased synthesis of ATPase and ATP
• Increased B-adrenergic receptor expression

Question 9

Hyperthyroidism clinical

Answer 9

• Weight loss
• Heat intolerance (and flushed skin)
• Arrhythmias
• Anxiety
• Oligomenorrhea
• Osteoporosis (bone resorption)
• GI hypermotility
• Thyroid myopathy

Question 10

Hyperthyroidism unique clinical

Answer 10

Lid lag (overstimulation of levator palpebrae superioris)

Question 11

Thyroid storm

Answer 11

Thyrotoxic crisis

• Life threatening hypermetabolic state
• Common in Graves with infection, surgery, stress

Question 12

Hyperthyroidism Dx

Answer 12

High free T3/4, low TSH

-Radioactive iodine uptake scan

Question 13

Drug for hyperthyroidism

Answer 13

B-blocker important for thyroid storm

Question 14

TSH secreting pituitary adenoma

Answer 14

Very rare

Question 15

Graves disease

Answer 15

IgG to TSH receptor stimulates growth and release, prevents normal TSH binding
-HLA-DR3 association

Question 16

Graves disease lab

Answer 16

• High T3/4, low TSH
• Hypocholesterolemia
• Hyperglycemia

Question 17

Graves clinical

Answer 17

• Exophthalmos and pretibial myxedema

- Diffuse goiter

Question 18

Exopthalmos mechanism

Answer 18

Glycosaminoglycans

Question 19

Graves histo

Answer 19

Scalloped border colloids

• Irregular follicles
• Chronic inflammation

Question 20

Graves Tx

Answer 20

B-blockers

• Thionamides
• Radioiodine ablation

Question 21

Hypothyroid cretinism

Answer 21

• Severe mental retardation
• Short stature
• Protruding tongue
• Umbilical hernia

Question 22

Hypothyroid myxedema non-skin

Answer 22

-Cold intolerance, obesity, constipation, decreased sweating, cool skin, reduced cardiac output, hypercholesterolemia, apathy

Question 23

Hypothyroid myxedema skin

Answer 23

Due to accumulation of glycosaminoglycans and hyaluronic acid
-Non pitting edema, broad face, enlarged tongue, deep voice

Question 24

Iodine deficiency goiter

Answer 24

• Diffuse: diffuse nodularity due to hyperplasia and involution
• Multinodular: chronic on/off periods
• Toxic: follicles become TSH-independent, leads to hyperthyroidism

Question 25

Hashimoto thyroiditis

Answer 25

Anti-microsomal, anti-thyroid peroxidase, and anti-thyroglobulin antibodies

Question 26

Hypothyroidism Dx

Answer 26

• Low T3/4
• High TSH in primary
• Normal or Low TSH in secondary

Question 27

Hypothyroidism Tx

Answer 27

Levothyroxine

Question 28

Hashimoto Thyroiditis mutation

Answer 28

HLA-DR5

Question 29

Hashimoto thyroiditis histo

Answer 29

• Lymphoid germinal centers
• Follicular atrophy
• Hurthle cells (metaplastic, eosinophilic, granular cells)

Question 30

Hashimoto thyroiditis clinical

Answer 30

Initial hyperthyroidism -> hypothyroidism after scarring

Question 31

Hashimoto thyroiditis cancer risk

Answer 31

MALT lymphoma (mucosa-associated lymphoid tissue)

Question 32

Subacute Granulomatous Thyroiditis

Answer 32

Transient painful hyperthyroidism following viral infection

-Coxsackie, mumps, measles, adenovirus

Question 33

Subacute granulomatous thyroiditis histo

Answer 33

Giant cell granules in chronic inflammation

Question 34

Reidel Fibrosing Thyroiditis

Answer 34

Chronic inflammation -> extensive fibrosis, destruction

-Hard as wood, painless thyroid

Question 35

Thyroid nodule in male

Answer 35

More likely to be neoplastic

Question 36

131-I radioactive uptake studies

Answer 36

• Hot Nodules - Graves disease/goiter

- Cold Nodules - Adenoma, malignancy

Question 37

Follicular adenoma

Answer 37

Benign nonfunctioning proliferation surrounded by Fibrous Capsule

• Unilateral, painless
• Rarely hyperfunctional or carcinoma

Question 38

Papillary Carcinoma

Answer 38

Asymptomatic until mass effect

• Most common (80%), excellent prognosis
• Fine Needle Aspiration test (unique nuclei)

Question 39

Papillary Carcinoma genetics

Answer 39

MAPk activation

• RET/PTC translocation (Pap.Thy.Carc.)
• BRAF mutation

Question 40

Papillary Carcinoma histo (5)

Answer 40

• Orphan Annie Eye nuclei
• Intranuclear grooves (coffee bean)
• Intranuclear cytoplasmic inclusions
• Psammoma bodies
• Branching papillae

Question 41

Follicular Carinoma

Answer 41

Distinguished from adenoma by invasion through fibrous capsule or vascular invasion

Question 42

Anaplastic Carcinoma

Answer 42

• So undifferentiated that thyroglobulin expression is lost
• Presents as fixed mass
• 6 months survival

Question 43

Medullary Thyroid Carcinoma

Answer 43

Derived from parafollicular C cells

-Calcitonin -> hypocalcemia

Question 44

Medullary Thyroid Carcinoma genetics

Answer 44

RET proto-oncogene mutation

• FMTC (familiar medullary thyroid carcinoma syndrome)
• MEN syndrome 2A/B (multiple endocrine neoplasia)
• Prophylactic thyroidectomy for known RET mutations

Question 45

Medullary Thyroid Carcinoma histo

Answer 45

Amyloid stromal background (from calcitonin)

-Membrane bound granules in EM