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Endo > SM_178b: Thyroid Pathophysiology & Nodules / Cancer > Flashcards

SM_178b: Thyroid Pathophysiology & Nodules / Cancer Flashcards

1
Q

Describe the hypothalamus-pituitary-thyroid negative feedback loop

A

Hypothalamus-pituitary-thyroid negative feedback loop

  1. Hypothalamus secretes TRH
  2. Pituitary secretes TSH
  3. Thyroid secretes T4, T3
  4. Peripheral cell and T4, T3 negatively feedback onto pituitary and hypothalamus
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2
Q

In hypothyroidism, TSH is ____, T4 is ____, and T3 is ____

A

In hypothyroidism, TSH is high, T4 is low, and T3 is low

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3
Q

In hyperthyroidism, TSH is ____, T4 is ____, and T3 is ____

A

In hyperthyroidism, TSH is low, T4 is high, and T3 is high

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4
Q

Hypothyroidism can be ____, ____, or ____

A

Hypothyroidism can be primary, surgical, or central

  • Primary: autoimmune destruction (Hashimoto’s) in iodine-sufficient population, iodine deficiency is most common worldwide, radiation induced
  • Central hypothyroidism: primary pituitary, TBI
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5
Q

24 yo woman with fatigue, constipation, and weight gain over past 7 months and family Hx of thyroid disease. Next step is to ___

A

24 yo woman with fatigue, constipation, and weight gain over past 7 months and family Hx of thyroid disease. Next step is to check TSH

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6
Q

Low TSH. low fT4, and high TPO antibody indicates ____

A

Low TSH. low fT4, and high TPO antibody indicates Hashimoto’s thyroiditis

  • Treat with levothyroxine, TSH monitoring
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7
Q

Hashimoto’s thyroiditis ultrasound shows ____

A

Hashimoto’s thyroiditis ultrasound shows heterogeneous (hypoechoic) echotexture

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8
Q

Hypothyroidism often presents with ____ such as ____, ____, ____, and ____

A

Hypothyroidism often presents with nonspecific symptoms such as fatigue, weight gain, constipation, and hair/skin changes

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9
Q

Subclinical hypothyroidism is ____

A

Subclinical hypothyroidism is elevated TSH with normal T4

  • Always treat if TSH > 10
  • Treat TSH > 7 if age < 65, possible prevention of CV outcomes and improvement in lipids
  • Always treat in pregnancy
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10
Q

Mechanism of levothyroxine for treating hypothyroidism is ___

A

Mechanism of levothyroxine for treating hypothyroidism is conversion of T3 by mono-deiodinases which helps normalize TSJ

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11
Q

Overt hypothyroidism is ____

A

Overt hypothyroidism is high TSH and low fT4

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12
Q

____ treats hypothyroidism

A

Levothyroxine treats hypothyroidism

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13
Q

Hyperthyroidism is when ____

A

Hyperthyroidism is when elevated T3 and T4 cause decreased TSH

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14
Q

_____, _____, and _____ are the most common causes of thyrotoxicosis and hyperthyroidism

A

Graves disease, toxic multinoudlar goiter, and thyroiditis are the most common causes of thyrotoxicosis and hyperthyroidism

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15
Q

Describe presentation of hyperthyroidism

A

Hyperthyroidism

  • Weight loss despite increase in appetite
  • Heat intolerance
  • Hyperactivity
  • Fatigue
  • Irritability
  • Tremor
  • Anxiety
  • Insomnia
  • Menstrual disturbances
  • SOB
  • Palpitations
  • Pelvic and pectoral girdle muscle weakness
  • Sleep disturbance
  • Weakness
  • Eye pain, tearing, gritty feeling
  • Tachycardia, wide pulse pressure, systolic HTN, dynamic precordium, brisk reflexes, tremor of outstretched hands
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16
Q

____ and ____ confirm diagnosis of Graves disease

A

Ultrasound and antibodies confirm diagnosis of Graves disease

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17
Q

Hyperthryoidism treatment involves ____ and ____

A

Hyperthryoidism treatment involves beta blockers for rapid amelioration of adrenergic symptoms (cardiac exam) and methimazole

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18
Q

Methimazole is commonly used to treat ____

A

Methimazole is commonly used to treat hyperthyroidism

  • First line anti-thyroid drug
  • Short term: to cool the patient down prior to RAI or surgery
  • Long-term: generally continued for 12-18 months then stopped to assess for remission
  • Side effects: agranulocytosis (major), rash / urticaria / pruritis / fever / GI (minor)
  • Recheck TSH, fT4 and T3 in 4 weeks and TSI every other lab check
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19
Q

Propylthiouracil can cause side effect of ____

A

Propylthiouracil can cause side effect of severe liver injury (fulminant hepatic necrosis)

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20
Q

____ is an option to treat hyperthyroidism for patients with large toxic nodular goiters and compressive symptoms, pregnant women with large anti-thyroid drug doses, pre-pregnancy, and patients with severe drug-related adverse effect

A

Total thyroidectomy is an option to treat hyperthyroidism for patients with large toxic nodular goiters and compressive symptoms, pregnant women with large anti-thyroid drug doses, pre-pregnancy, and patients with severe drug-related adverse effect

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21
Q

Graves ophthalmopathy (thyroid eye disease) presents with ____, ____, ____, and ____

A

Graves ophthalmopathy (thyroid eye disease) presents with proptosis, diplopia, optic nerve involvement, and inflammatory changes including conjunctival injection / periorbital edema / chemosis

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22
Q

____ is used to treat Graves ophthalmopathy (thyroid eye disease

A

Teprotumumab is used to treat Graves ophthalmopathy (thyroid eye disease

(monoclonal Ab that inhibits IGF1R, IGF1R and TSHR both located on orbital fibrocytes)

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23
Q

____ clinical manifestation of excess thyroid hormone action at the tissue level due to inappropriately high circulating thyroid hormone concentrations

A

Thyrotoxicosis is the clinical manifestation of excess thyroid hormone action at the tissue level due to inappropriately high circulating thyroid hormone concentrations

(hyperthyroidism is a subset)

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24
Q

Describe different thyroid scans in thyrotoxicosis

A

Thyroid scans in thyrotoxicosis

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25
Q

These thyroid scans represent ____

A

These thyroid scans represent Graves disease

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26
Q

This thyroid scan represents a ____

A

This thyroid scan represents a toxic adenoma

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27
Q

This thyroid scan represents a ____

A

This thyroid scan represents a toxic multinodular goiter

28
Q

____ supplementation for hair and nails can lead to low TSH and high T4 and T3

A

Biotin supplementation for hair and nails can lead to low TSH and high T4 and T3

  • Biotin can lead to false results by capturing monoclonal antibodies
29
Q

Low TSH and presenting with hair loss postpartum and stress might be ____

A

Low TSH and presenting with hair loss postpartum and stress might be biotin supplementation

30
Q

Low TSH, neck tenderness to palpation, and recent URI is ____

A

Low TSH, neck tenderness to palpation, and recent URI is painful thyroiditis

  • Ultrasound is chaotic if patient lets you image
  • I-123 scan shows no uptake
  • ESR high
  • Low grade fever
  • TSH suppressed, fT4 high, total T3 less elevated
  • NSAIDs, prednosine (often)
31
Q

Thyroiditis is ___

A

Thyroiditis is damage to thyroid gland

  • Leakage of stored thyroid hormone causing thyrotoxicosis: lasts 6-8 weeks until stored thyroid hormone is depleted
  • Return to euthyroid state orwing to transient hypothyroidism (damaged follicular cells need to recover)
32
Q

Low TSH and postpartum may be ___

A

Low TSH and postpartum may be postpartum thyroiditis

33
Q

Gestational thyrotoxicosis is ___

A

Gestational thyrotoxicosis is hCG-mediated increase in thyroid hormone production

  • Occurs in late 1st and early 2nd trimesters with improvement as hCG decreases
34
Q

Gestational thyrotoxicosis has ____ and ____

A

Gestational thyrotoxicosis has no goiter and negative TSH receptor antibody

35
Q

Subclinical hyperthyroidism is ____ TSH, ____ fT4, and ____ T3

A

Subclinical hyperthyroidism is persistently low TSH, normal fT4, and normal T3

  • Cardiac (Afib, heart failure), bone, mortality
36
Q

Incidence of atrial fibrillation ____ with decreasing serum TSH

A

Incidence of atrial fibrillation increases with decreasing serum TSH

37
Q

High risk of fracture is subclinical hyperthyroidism with TSH ___ or endogenous cause

A

High risk of fracture is subclinical hyperthyroidism with TSH < 0.1 mIU/L or endogenous cause

38
Q

TSI, TBII, and TRAb are for ___

A

TSI, TBII, and TRAb are for Graves disease

39
Q

Up to ____ of people have thyroid nodules but risk of cancer in thyroid nodule is ____

A

Up to 60% of people have thyroid nodules but risk of cancer in thyroid nodule is 10%

  • Many more detected on ultrasound than palpation
  • Some noted by patient, third party, or other tests
40
Q

Thyroid neoplasms can be ____ or ____

A

Thyroid neoplasms can be benign or malignant

41
Q

Thyroid adenoma requires ___

A

Thyroid adenoma requires careful evaluation of the capsule

  • Benign neoplasm
  • Solitary nodule
  • Follicular / Hurthle cell
42
Q
A
43
Q

First step in evaluating thyroid nodule is ____

A

First step in evaluating thyroid nodule is TSH

  • If TSH is low, do a thyroid scan
  • If TSH is normal / high, do ultrasound
44
Q
A
45
Q

Describe ATA patterns

A

ATA patterns

  • 3 points -> TR3 mildly suspicious -> FNA if ≥ 25 cm, follow if ≥ 1.5 cm
  • 4-6 points -> TR4 moderately suspicious -> FNA if ≥ 1.5 cm, follow if ≥ 1 cm
46
Q

Thyroid nodules are suspicious if ___

A

Thyroid nodules are suspicious if hypoechoic solid nodule or partially cystic nodule with ≥ 1 of the following suspicious features

  • Microcalcifications
  • Shape taller than wide
  • Irregular margins
  • Extrathyroidal extension
  • Interrupted rim calcifications with soft tissue

(risk of malignancy > 70-90%)

47
Q

Intermediate thyroid nodule suspicion pattern is ___

A

Intermediate thyroid nodule suspicion pattern is hypoechoic nodules with regular smooth margins

  • Papillary carcinoma, benign hyperplastic nodule
48
Q

Low thyroid nodule suspicion pattern is ___

A

Low thyroid nodule suspicion pattern is iso- to hyperechoic nodules with regular margins

  • Benign Hurthle cell adenoma, PTC foll variant, hyperplastic nodule
49
Q

Very low thyroid nodule suspicion pattern is ___

A

Very low thyroid nodule suspicion pattern is mixed cystic / solid nodules (spongiform)

50
Q

Pure cystic thyroid nodule is most likely ___

A

Pure cystic thyroid nodule is most likely benign

51
Q

ACR TI-RADS is ___

A

ACR TI-RADS is guidelines for thyroid nodules discovered incidentally

52
Q

If thyroid nodule is suspected to be malignant after fine needle biopsy, patient is treated with ____

A

If thyroid nodule is suspected to be malignant after fine needle biopsy, patient is treated with thyroidectomy

53
Q

Describe what to do after fine needle aspiration for thyroid nodule

A

Fine needle aspiration for thyroid nodule

  • Benign (60-70%): follow
  • Malignant (10%): surgery
  • Inadequate (5%): repeat biopsy
  • Suspicious / indeterminate (20%): ultrasound features or molecular markers
54
Q

Molecular testing is used to inform management of ___ thyroid nodules

A

Molecular testing is used to inform management of indeterminate nodules

  • High sensitivity and NPV
55
Q

Most common thyroid cancer is ____, which originates from ____

A

Most common thyroid cancer is papillary cancer, which originates from follicular thyroid cells (well-differentiated)

56
Q

Describe papillary carcinoma

A

Papillary carcinoma

  • Most common
  • Well-differentiated
  • Multifocal
  • Lymphatic spread
  • Excellent prognosis
  • Papillae with vascular core
  • Optically clear nuclei
  • Nuclear pseudoinclusions
  • Nuclear grooves
  • Rare or absent mitoses
  • Psammoma bodies
57
Q

Follicular carcinoma is ____ or ____

A

Follicular carcinoma is minimally invasive or widely invasive

  • Minimally invasive: vascular or capsular invasion
  • Widely invasive: more extensive invasion into the surrounding muscle, vessels, trachea, etc
58
Q

Describe treatment of thyroid cancer

A

Thyroid cancer treatment

  1. Lobectomy or total thyroidectomy
  2. Radioactive iodine treatment and postop thyroglobulin and ultrasound
  3. LT4 for TSH suppression
59
Q

Increasing suppression of TSH leads to ____, ____, and ____

A

Increasing suppression of TSH leads to increased risk of atrial fibrillation, aggravation of postmenopausal osteoporosis, and increased risk of signs / symptoms of thyrotoxicosis

  • The higher risk the cancer history, the lower TSH should be
60
Q

Anaplastic carcinoma of thyroid has three patterns: ____, ____, and ____

A

Anaplastic carcinoma of thyroid has three patterns: spindle cell, giant cell, and squamoid cells

  • Older age group (poor survival)
  • Rapidly growing mass
  • Necrosis and hemorrhage
61
Q

Medullary thyroid carcinoma is a ____ that produces ____ and ____

A

Medullary thyroid carcinoma is a neuroendocrine tumor of the parafollicular C cells that produces calcitonin or carcinoembryonic antigen

  • Most sporadic, others hereditary due to MEN type 2
62
Q

MEN 2 is an ____ disorder caused by mutations in the ____ proto-oncogene

A

MEN 2 is an autosomal dominant disorder caused by mutations in the RET proto-oncogene

  • Strong genotype-phenoptye correlation
  • MEN2A: medullary thyroid cancer, pheochromocytoma, hyperparathyroidism
  • MEN2B: medullary thyroid cancer, pheochromocytoma, ganglioneuromas, marfanoid habitus
63
Q

Once medullary thyroid cancer diagnosis is established, ____, ____, and ____

A

Once medullary thyroid cancer diagnosis is established

  • Screen for pheochromocytoma with 24 hour or plasma free metanephrine measurement
  • Determine Ca and PTH if hyperparathyroidism possible
  • RET gene analysis
64
Q

In medullary thyroid cancer, it is not usually possible to localize residual / recurrent disease unless ___

A

In medullary thyroid cancer, it is not usually possible to localize residual / recurrent disease unless calcitonin > 150 pg/ml

65
Q

____ are large fleshy masses that often arise in long-standing autoimmune thyroiditis

A

Lymphomas are large fleshy masses that often arise in long-standing autoimmune thyroiditis

  • Usually B cell lymphoma

Endo (25 decks)

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