10/8- Disease of the Thyroid I

Question 1

What is a goiter?

Answer 1

Chronic enlargement of the thyroid gland not due to neoplasm

Question 2

What is an endemic goiter?

• Epidemiology

Answer 2

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

Question 3

What is a sporadic goiter?

Answer 3

• 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

Question 4

What are possible etiologies behind goiter?

Answer 4

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

Question 5

Describe the possible goiter in Hashimoto’s thyroiditis

Answer 5

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

Question 6

What causes goiter in Graves’ disease?

Answer 6

Chronic stimulation of TSH receptor

Question 7

How does chronic iodine excess cause goiter?

Answer 7

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

Question 8

How dose lithium cause goiter?

Answer 8

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

Question 9

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

Answer 9

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%.

Question 10

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

Answer 10

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)

Question 11

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

Answer 11

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

Question 12

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

Answer 12

• 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

Question 13

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

Answer 13

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

Question 14

How are types of thyroid nodules determined?

Answer 14

Based on uptake scan and on USS

Question 15

What is the prevalence of thyroid nodules?

Answer 15

10-15% of US population

Question 16

Approach to the thyroid nodule?

Answer 16

• Labs
• USS
• RAIUS
• FNA

Question 17

Pathophysiology of Nodules

• Benign
• Malignant

Answer 17

Benign (~95%):

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

Malignant (~5%):

• Primary carcinoma
• Lymphoma
• Mets

Question 18

A single nodule should raise the possibility of what?

Especially if what association?

Answer 18

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

~ 15-20 % of cold nodules are malignant

Question 19

What do hot nodules reflect?

Answer 19

Hyperfunction causing hyperthyroidism

Question 20

Which nodules have higher malignancy potential, solid or cystic?

Answer 20

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

Question 21

When do you suspect malignancy in nodular thyroid disease?

Answer 21

• 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

Question 22

What are the FNA guidelines for diagnosing a thyroid nodule?

Answer 22

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

Question 23

What may cause thyroiditis/what are the different types?

Answer 23

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

Question 24

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

Answer 24

Hashimoto’s thyroiditis

Question 25

What causes Hashimoto's thyroiditis? - Gland size

Answer 25

- Result of antibodies to TPO, TBG - AI disease with progressive gland destruction - Gland size varies from goitrous enlargement to an impalpable gland

Question 26

Hashimoto's thyroiditis typically presents in what population?

Answer 26

Females 30-50 yrs.

Question 27

What are clinical features of Hashimoto's thyroiditis? - Physical exam findings - Lab studies

Answer 27

_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%)

Question 28

Treatment for Hashimoto's thyroiditis?

Answer 28

Levothyroxine if hypothyroid - Replace thyroid hormone

Question 29

What is Subacute (de Quervains) Thyroiditis? - Prognosis

Answer 29

- Self limiting disease of variable duration & severity - Most common cause of a (exquisitely) painful thyroid gland, likely secondary to an antecedent viral infection

Question 30

How to diagnose Subacute (de Quervains) Thyroiditis?

Answer 30

- Elevated ESR - Low TSH, elevated T4 \> T3 - Low anti-TPO/Tgb - Low RAI uptake (same as silent thyroiditis)

Question 31

What is the course of Subacute (de Quervains) Thyroiditis?

Answer 31

- Pain and thyrotoxicosis (3-6 weeks) - Asymptomatic euthyroidism - Hypothyroid period (weeks to months) - Recovery (complete in 95% after 4-6 months)

Question 32

Treatment during the early painful stage of Subacute (de Quervains) Thyroiditis includes what?

Answer 32

- **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

Question 33

What is silent thyroiditis? - Clinical features

Answer 33

- "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

Question 34

How is silent thyroiditis diagnoses complicated?

Answer 34

May be confused with post-partum Graves' relapse

Question 35

Treatment for silent thyroiditis?

Answer 35

- Beta blockers during toxic phase - No anti-thyroid medication indicated - Iodinated Rx for severe hyperthyroidism - Thyroid hormone during hypothyroid phase.

Question 36

What is the very broad progression of thyroid function in thyroiditis (pretty much all types)?

Answer 36

Hyperthyroid -\> transient euthyroid -\> possibly hypothyroid

Question 37

What are causes of acute thyroiditis?

Answer 37

_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)

Question 38

How is acute thyroiditis diagnosed?

Answer 38

- 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

Question 39

Treatment for acute thyroiditis?

Answer 39

- High mortality without prompt treatment - IV Antibiotics - Search for pyriform fistulae (BA swallow, endoscopy) - Recovery is usually complete

Question 40

What is Reidel's thyroiditis?

Answer 40

Rare disease causing fibrosis of the thyroid gland

Question 41

How is Riedel's Thyroiditis diagnosed?

Answer 41

- 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)

Question 42

Treatment for Riedel's Thyroiditis?

Answer 42

- Resection for compressive symptoms - Steroids may be effective - Thyroid hormone only if hypothyroidism