Path 6 Thyroid Flashcards Preview

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Flashcards in Path 6 Thyroid Deck (45):
1

C cells

Neuroendocrine parafollicular cells that secrete calcitonin

2

Calcitonin function (4)

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

3

Thyroid regulation

++ Thyrotropin (TSH)

4

Thyroid follicular cell function

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

5

T3 and T4 in plasma

Bound to transthyretin

6

T3 and T4 in cells

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

7

2 congenital thyroid malformation

-Thyroglossal duct cyst
-Lingual thyroid

8

Hyperthyroidism cell effects

Mediated by T3
-Increased synthesis of ATPase and ATP
-Increased B-adrenergic receptor expression

9

Hyperthyroidism clinical

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

10

Hyperthyroidism unique clinical

Lid lag (overstimulation of levator palpebrae superioris)

11

Thyroid storm

Thyrotoxic crisis
-Life threatening hypermetabolic state
-Common in Graves with infection, surgery, stress

12

Hyperthyroidism Dx

High free T3/4, low TSH
-Radioactive iodine uptake scan

13

Drug for hyperthyroidism

B-blocker important for thyroid storm

14

TSH secreting pituitary adenoma

Very rare

15

Graves disease

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

16

Graves disease lab

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

17

Graves clinical

-Exophthalmos and pretibial myxedema
-Diffuse goiter

18

Exopthalmos mechanism

Glycosaminoglycans

19

Graves histo

Scalloped border colloids
-Irregular follicles
-Chronic inflammation

20

Graves Tx

B-blockers
-Thionamides
-Radioiodine ablation

21

Hypothyroid cretinism

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

22

Hypothyroid myxedema non-skin

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

23

Hypothyroid myxedema skin

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

24

Iodine deficiency goiter

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

25

Hashimoto thyroiditis

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

26

Hypothyroidism Dx

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

27

Hypothyroidism Tx

Levothyroxine

28

Hashimoto Thyroiditis mutation

HLA-DR5

29

Hashimoto thyroiditis histo

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

30

Hashimoto thyroiditis clinical

Initial hyperthyroidism -> hypothyroidism after scarring

31

Hashimoto thyroiditis cancer risk

MALT lymphoma (mucosa-associated lymphoid tissue)

32

Subacute Granulomatous Thyroiditis

Transient painful hyperthyroidism following viral infection
-Coxsackie, mumps, measles, adenovirus

33

Subacute granulomatous thyroiditis histo

Giant cell granules in chronic inflammation

34

Reidel Fibrosing Thyroiditis

Chronic inflammation -> extensive fibrosis, destruction
-Hard as wood, painless thyroid

35

Thyroid nodule in male

More likely to be neoplastic

36

131-I radioactive uptake studies

-Hot Nodules - Graves disease/goiter
-Cold Nodules - Adenoma, malignancy

37

Follicular adenoma

Benign nonfunctioning proliferation surrounded by Fibrous Capsule
-Unilateral, painless
-Rarely hyperfunctional or carcinoma

38

Papillary Carcinoma

Asymptomatic until mass effect
-Most common (80%), excellent prognosis
-Fine Needle Aspiration test (unique nuclei)

39

Papillary Carcinoma genetics

MAPk activation
-RET/PTC translocation (Pap.Thy.Carc.)
-BRAF mutation

40

Papillary Carcinoma histo (5)

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

41

Follicular Carinoma

Distinguished from adenoma by invasion through fibrous capsule or vascular invasion

42

Anaplastic Carcinoma

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

43

Medullary Thyroid Carcinoma

Derived from parafollicular C cells
-Calcitonin -> hypocalcemia

44

Medullary Thyroid Carcinoma genetics

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

45

Medullary Thyroid Carcinoma histo

Amyloid stromal background (from calcitonin)
-Membrane bound granules in EM