10/8- Disease of the Thyroid I Flashcards

1
Q

What is a goiter?

A

Chronic enlargement of the thyroid gland not due to neoplasm

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2
Q

What is an endemic goiter?

  • Epidemiology
A
  • Areas where > 5% of children 6-12 years of age have goiter
  • Common in China and central Africa, Himalayan foothills, Andes
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3
Q

What is a sporadic goiter?

A
  • Occurs in areas where < 5% of children 6-12 yo have goiter
  • Multinodular goiter often denotes the presence of multiple nodules rather than gross gland enlargement
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4
Q

What are possible etiologies behind goiter?

A
  • Hashimoto’s thyroiditis
  • Graves’ disease
  • Chronic Iodine excess
  • Medications: Lithium
  • Neoplasm
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5
Q

Describe the possible goiter in Hashimoto’s thyroiditis

A
  • Goiter may be present in early stages only, late stages show atrophic changes
  • May present with hypo, hyper, or euthyroid state
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6
Q

What causes goiter in Graves’ disease?

A

Chronic stimulation of TSH receptor

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7
Q

How does chronic iodine excess cause goiter?

A

Iodine excess leads to increased colloid formation and can prevent hormone release

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8
Q

How dose lithium cause goiter?

A

Lithium prevents release of hormone, causes goiter in 6% of chronic users

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9
Q

What is the pathogenesis behind goiter in iodine deficient vs. replete areas?

A

Iodine deficient areas:

  • Heterogeneous response to TSH
  • Chronic stimulation leads to multiple nodules

Iodine replete areas

  • Thyroid follicles are heterogeneous in their growth and activity potentia
  • Autopsy series show MNG - 30%.
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10
Q

What evaluation should be done if a pt has a goiter?

A

Determination of thyroid state is key in determining treatment!

Thyroid function evaluation:

  • TSH, T4, T3
  • Overt hyperthyroidism (TSH low, T3/T4 high)
  • Subclinical hyperthyroidism (TSH low, T3/T4 normal)
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11
Q

What should be screened for with non-toxic MNG (multi-nodular goiter)?

A

Longstanding MNG has a risk of malignancy identical to solitary nodules FNA in MNG

  • Negative FNA can be followed with annual US
  • Insufficient FNA’s should be repeated
  • Inconclusive FNA or papillary cytology warrants excision
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12
Q

What are treatment options for a non-toxic goiter not causing compressive symptoms?

A
  • US follow-up to monitor for progression
  • Thyroid suppression therapy has been used historically
  • May be used for progressive growth
  • Goiter re-growth occurs rapidly following therapy cessation
  • Surgery
  • Suspicious neck lymphadenopathy
  • History of radiation to the cervical region
  • Rapid enlargement of nodules
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13
Q

What are treatment options for a non-toxic goiter that is causing compressive symptoms?

A

RAI (radio-active iodine) ablation

  • Not a treatment of choice due to SLOW process
  • Volume reduction
  • Improvement of dysphagia or dyspnea
  • Post RAI hypothyroidism (pretty inevitable)
  • Need for additional ablation depends on size of gland, number of nodules and dose of original ablation

Surgery

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14
Q

How are types of thyroid nodules determined?

A

Based on uptake scan and on USS

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15
Q

What is the prevalence of thyroid nodules?

A

10-15% of US population

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16
Q

Approach to the thyroid nodule?

A
  • Labs
  • USS
  • RAIUS
  • FNA
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17
Q

Pathophysiology of Nodules

  • Benign
  • Malignant
A

Benign (~95%):

  • MNG
  • Hashimoto’s
  • Cysts
  • Adenomas
  • Hurthle-cell adenoma

Malignant (~5%):

  • Primary carcinoma
  • Lymphoma
  • Mets
18
Q

A single nodule should raise the possibility of what?

Especially if what association?

A

A single nodule, especially if associated with a cold defect, should always raise the possibility of malignancy

~ 15-20 % of cold nodules are malignant

19
Q

What do hot nodules reflect?

A

Hyperfunction causing hyperthyroidism

20
Q

Which nodules have higher malignancy potential, solid or cystic?

A

Solid nodules have a higher malignancy potential, but cystic nodules >4cm also pose cancer risk

21
Q

When do you suspect malignancy in nodular thyroid disease?

A
  • Age : children; nodules in young patients, or new nodules in the older patient (age under 30 or over 60)
  • Gender : though all forms of thyroid disease are more common in women, malignancy is more likely in the male patient with a thyroid nodule
  • Rapid enlargement in size
  • Hard nodules
  • Family history of thyroid cancer
  • Previous head and neck irradiation
  • Cold defects
22
Q

What are the FNA guidelines for diagnosing a thyroid nodule?

A
  • All hypoechoic nodules ≥ 10 mm
  • Irregular margins
  • Chaotic intra-nodular vascular spots
  • Micro-calcifications
23
Q

What may cause thyroiditis/what are the different types?

A
  • Hashimoto’s thyroiditis
  • Subacute thyroiditis
  • Silent / Post-partum thyroiditis
  • Acute thyroiditis
  • Riedel’s thyroiditis
24
Q

What is the most common cause of goiter and hypothyroidism in the US?

A

Hashimoto’s thyroiditis

25
What causes Hashimoto's thyroiditis? - Gland size
- Result of antibodies to TPO, TBG - AI disease with progressive gland destruction - Gland size varies from goitrous enlargement to an impalpable gland
26
Hashimoto's thyroiditis typically presents in what population?
Females 30-50 yrs.
27
What are clinical features of Hashimoto's thyroiditis? - Physical exam findings - Lab studies
_Clinical features_ - Reflect a hyper- or hypothyroid state depending on the natural progression of the disease. _Physical_: - Usually non-tender and asymptomatic _Lab studies_ - Hypothyroidism (elevated TSH) - Abs are typically positive * Anti TPO antibodies (90%) * Anti Thyroglobulin antibodies (20-50%) - Acute Hyperthyroidism (5%)
28
Treatment for Hashimoto's thyroiditis?
Levothyroxine if hypothyroid - Replace thyroid hormone
29
What is Subacute (de Quervains) Thyroiditis? - Prognosis
- Self limiting disease of variable duration & severity - Most common cause of a (exquisitely) painful thyroid gland, likely secondary to an antecedent viral infection
30
How to diagnose Subacute (de Quervains) Thyroiditis?
- Elevated ESR - Low TSH, elevated T4 \> T3 - Low anti-TPO/Tgb - Low RAI uptake (same as silent thyroiditis)
31
What is the course of Subacute (de Quervains) Thyroiditis?
- Pain and thyrotoxicosis (3-6 weeks) - Asymptomatic euthyroidism - Hypothyroid period (weeks to months) - Recovery (complete in 95% after 4-6 months)
32
Treatment during the early painful stage of Subacute (de Quervains) Thyroiditis includes what?
- **NSAID’s** and **salicylates**. - **Oral steroids** in **severe** cases (powerful anti-inflammatory effect) - **Beta blockers** for symptoms of **hyperthyroidism** (thyroid hormones act through B adrenergic receptors; provide relief from tachycardia, palpitations, etc.) - **Thionamides NOT** indicated since excess hormone results from leak instead of hyperfunction - Symptoms can recur requiring repeat treatment
33
What is silent thyroiditis? - Clinical features
- "Post-partum thyroiditis" if it occurs within 1 yr of delivery _Clinically:_ - PAINLESS - Hyperthyroid symptoms at presentation - Progression to euthyroidism followed by hypothyroidism for up to 1 year. - Hypothyroidism generally resolves
34
How is silent thyroiditis diagnoses complicated?
May be confused with post-partum Graves' relapse
35
Treatment for silent thyroiditis?
- Beta blockers during toxic phase - No anti-thyroid medication indicated - Iodinated Rx for severe hyperthyroidism - Thyroid hormone during hypothyroid phase.
36
What is the very broad progression of thyroid function in thyroiditis (pretty much all types)?
Hyperthyroid -\> transient euthyroid -\> possibly hypothyroid
37
What are causes of acute thyroiditis?
_Infection_ - Bacterial (S aureus, S pyogenes) (68%) - Fungal (15%) - Mycobacterial (9%) - Common in HIV _Secondary to:_ - Pyriform sinus fistulae - Pharyngeal space infections - Persistent thyroglossal remnants - Thyroid surgery wound infections (rare)
38
How is acute thyroiditis diagnosed?
- Warm, tender, enlarged thyroid (don't confuse with subacute thyroiditis) - FNA to drain abscess, obtain culture - RAIU normal * Pretty much just infection of euthyroid/normally functioning thyroid * Contrast to decreased function in DeQuervain’s - CT or US if infected TGDC suspected
39
Treatment for acute thyroiditis?
- High mortality without prompt treatment - IV Antibiotics - Search for pyriform fistulae (BA swallow, endoscopy) - Recovery is usually complete
40
What is Reidel's thyroiditis?
Rare disease causing fibrosis of the thyroid gland
41
How is Riedel's Thyroiditis diagnosed?
- Thyroid Ab’s present in 2/3 - Painless goiter “woody” - Open biopsy often needed to diagnose - Associated with focal sclerosis syndromes (retroperitoneal, mediastinal, retroorbital, and sclerosing cholangitis)
42
Treatment for Riedel's Thyroiditis?
- Resection for compressive symptoms - Steroids may be effective - Thyroid hormone only if hypothyroidism