10/8- Disease of the Thyroid I Flashcards
What is a goiter?
Chronic enlargement of the thyroid gland not due to neoplasm
What is an endemic goiter?
- Epidemiology
- Areas where > 5% of children 6-12 years of age have goiter
- Common in China and central Africa, Himalayan foothills, Andes
What is a sporadic goiter?
- 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
What are possible etiologies behind goiter?
- Hashimoto’s thyroiditis
- Graves’ disease
- Chronic Iodine excess
- Medications: Lithium
- Neoplasm
Describe the possible goiter in Hashimoto’s thyroiditis
- Goiter may be present in early stages only, late stages show atrophic changes
- May present with hypo, hyper, or euthyroid state
What causes goiter in Graves’ disease?
Chronic stimulation of TSH receptor
How does chronic iodine excess cause goiter?
Iodine excess leads to increased colloid formation and can prevent hormone release
How dose lithium cause goiter?
Lithium prevents release of hormone, causes goiter in 6% of chronic users
What is the pathogenesis behind goiter in iodine deficient vs. replete areas?
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%.
What evaluation should be done if a pt has a goiter?
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)
What should be screened for with non-toxic MNG (multi-nodular goiter)?
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
What are treatment options for a non-toxic goiter not causing compressive symptoms?
- 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
What are treatment options for a non-toxic goiter that is causing compressive symptoms?
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
How are types of thyroid nodules determined?
Based on uptake scan and on USS
What is the prevalence of thyroid nodules?
10-15% of US population
Approach to the thyroid nodule?
- Labs
- USS
- RAIUS
- FNA
Pathophysiology of Nodules
- Benign
- Malignant
Benign (~95%):
- MNG
- Hashimoto’s
- Cysts
- Adenomas
- Hurthle-cell adenoma
Malignant (~5%):
- Primary carcinoma
- Lymphoma
- Mets
A single nodule should raise the possibility of what?
Especially if what association?
A single nodule, especially if associated with a cold defect, should always raise the possibility of malignancy
~ 15-20 % of cold nodules are malignant
What do hot nodules reflect?
Hyperfunction causing hyperthyroidism
Which nodules have higher malignancy potential, solid or cystic?
Solid nodules have a higher malignancy potential, but cystic nodules >4cm also pose cancer risk
When do you suspect malignancy in nodular thyroid disease?
- 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
What are the FNA guidelines for diagnosing a thyroid nodule?
- All hypoechoic nodules ≥ 10 mm
- Irregular margins
- Chaotic intra-nodular vascular spots
- Micro-calcifications
What may cause thyroiditis/what are the different types?
- Hashimoto’s thyroiditis
- Subacute thyroiditis
- Silent / Post-partum thyroiditis
- Acute thyroiditis
- Riedel’s thyroiditis
What is the most common cause of goiter and hypothyroidism in the US?
Hashimoto’s thyroiditis
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
Hashimoto’s thyroiditis typically presents in what population?
Females 30-50 yrs.
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%)
Treatment for Hashimoto’s thyroiditis?
Levothyroxine if hypothyroid
- Replace thyroid hormone
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
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)
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)
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
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
How is silent thyroiditis diagnoses complicated?
May be confused with post-partum Graves’ relapse
Treatment for silent thyroiditis?
- Beta blockers during toxic phase
- No anti-thyroid medication indicated
- Iodinated Rx for severe hyperthyroidism
- Thyroid hormone during hypothyroid phase.
What is the very broad progression of thyroid function in thyroiditis (pretty much all types)?
Hyperthyroid -> transient euthyroid -> possibly hypothyroid
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)
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
Treatment for acute thyroiditis?
- High mortality without prompt treatment
- IV Antibiotics
- Search for pyriform fistulae (BA swallow, endoscopy)
- Recovery is usually complete
What is Reidel’s thyroiditis?
Rare disease causing fibrosis of the thyroid gland
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)
Treatment for Riedel’s Thyroiditis?
- Resection for compressive symptoms
- Steroids may be effective
- Thyroid hormone only if hypothyroidism
