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
