Thyroid Notes Flashcards
What is the shape and location of the thyroid gland?
Butterfly shaped and located at the base of the neck.
What are the lobes of the thyroid gland?
2 lobes (right and left) joined by an isthmus.
What is a common anatomical feature of the thyroid gland?
Asymmetry is common (RT>LT).
What anatomical structures are located posterior to the thyroid gland?
Trachea, esophagus, and neurovascular bundle.
What is the size range of the thyroid gland?
Length: 4 to 6 cm, AP: 2 cm, Width: 2 cm, Isthmus: 2 to 6 mm.
What arteries supply blood to the thyroid gland?
Right and left superior and inferior thyroid arteries.
What is the sonographic appearance of the thyroid gland?
Homogeneous with medium-level echoes and a hyperechoic thin capsule.
What is the functional unit of the thyroid gland?
The follicle.
What hormones are produced by the thyroid gland?
Thyroxine (T4), Triiodothyronine (T3), and Calcitonin.
What is hypothyroidism?
Under secretion of thyroid hormones resulting in decreased body metabolism.
What are common symptoms of hypothyroidism? 5
- Weight gain
- Hair loss
- Lethargy
- Cold intolerance
- Constipation.
What is hyperthyroidism?
Over secretion of hormones resulting in increased body metabolism.
What are common symptoms of hyperthyroidism? 4
- Weight loss
- Increased appetite
- Nervousness
- Palpitations.
What lab tests are used to assess thyroid function?
Serum T3, serum T4, serum TSH, and thyroid antibodies.
What is a thyroid scan?
A nuclear medicine test that determines thyroid function using radioisotopes.
What is a common benign focal disease of the thyroid?
Cysts, which can be true cysts or represent cystic degeneration of a follicular adenoma.
What is Hashimoto’s Thyroiditis?
A chronic lymphocytic inflammatory disease and the most common cause of adult hypothyroidism.
What is the sonographic appearance of Hashimoto’s Thyroiditis?
Diffuse heterogeneous enlargement of the gland, hypoechoic with possible discreet nodules.
What causes gland swelling and pain in thyroid conditions?
Due to a viral infection, the gland swells rapidly, is very painful and tender.
What is the initial thyroid function in viral infections?
Initially hyperthyroidism.
Does viral thyroid infection progress to hypothyroidism?
Rarely progresses to hypothyroidism.
What is the sonographic appearance of a gland affected by viral infection? 3
- Enlarged gland
- Hypoechoic
- Normal or decreased vascularity.
What characterizes Silent Thyroiditis? 3
- Enlarged gland with no pain;
- Sonographically resembles Hashimoto’s 3. Clinically resembles Subacute Granulomatous.
What is Invasive Fibrous (Riedel’s Struma)?
The rarest form of thyroid disease, typically resulting in complete destruction of the thyroid gland.
What are the characteristics of Hyperplasia in thyroid conditions? 3
- Goiter
- Diffuse enlargement of the thyroid
- With or without functional disturbances.
What causes a goiter?
Iodine deficiency or a defect in normal hormone synthesis.
What is Grave’s Disease?
A diffuse toxic goiter causing thyrotoxicosis and hyperthyroidism, an autoimmune disorder.
What are the common symptoms of Grave’s Disease? 3
- Exophthalmos
- Skin thickening at low extremities
- Clubbed toes and fingers.
What is the sonographic appearance of Grave’s Disease? 5
- Diffuse symmetrical enlargement
- Lobulated
- Homogenous or heterogenous
- Hypoechoic, ‘thyroid inferno’ -
- Hypervascularity.
What is a Non-toxic Goiter?
Related to a lack of iodine in the diet, with no functional disturbances and slow growth.
What is the sonographic appearance of a Non-toxic Goiter? 2
- Diffusely and uniformly enlarged
- Smooth or nodular echotexture.
What characterizes a Multinodular Goiter?
Adenomatous condition due to iodine deficiency leading to inadequate thyroid hormone production.
What is the sonographic appearance of a Multinodular Goiter? 4
- Enlarged and often asymmetrical
- Diffusely heterogeneous with multiple nodules
- Calcifications
- Cystic areas.
What are the characteristics of malignant thyroid diseases?
Women > men, typically slow growing, solitary nodules more worrisome than multiple.
What percentage of solitary ‘cold’ nodules are malignant?
20% of solitary ‘cold’ nodules are malignant.
What are common signs and symptoms of thyroid malignancy? 4
- Pressure symptoms
- Painless palpable neck mass
- Change in voice
- Hoarseness.
What is the sonographic appearance of malignant thyroid lesions? 7
- Variable
- Hypoechoic
- Poorly defined borders
- Jagged borders
- Absence of halo or incomplete halo
- Microcalcifications
- Taller than wide.
What is the most common type of thyroid cancer?
Papillary thyroid cancer (60-70%).
What are the characteristics of Papillary thyroid cancer?
- Least aggressive
- Slow growing
- May spread to cervical lymph nodes
- Often asymptomatic.
What is the sonographic appearance of Papillary thyroid cancer? 5
- Solid
- Often hypoechoic
- Microcalcifications
- Tiny - 10cm
- Hypervascularity.
What is Follicular thyroid cancer? How common is it?
15 to 20% of thyroid cancers, slow growing but more aggressive than papillary.
What are the characteristics of Medullary thyroid cancer? How common is it?
5% of thyroid cancers, hard bulky mass, metastasizes readily, secretes calcitonin.
What characterizes Anaplastic thyroid cancer? How common is it? 3
- Rarest and most aggressive
- Invades adjacent structures
- Typically in older patients (> 60 years).
What is the sonographic appearance of Anaplastic thyroid cancer? 5
- Hypoechoic
- Solid
- Irregular
- Encasing/invading blood vessels
- Neck muscles.
What is Lymphoma in the context of thyroid diseases? 3
- Primarily non-Hodgkin’s
- Rapidly growing mass
- History of Hashimoto’s.
What are the characteristics of metastatic thyroid diseases? 3
- Infrequent
- Spread through hematogenous route
- Commonly from breast, lung, colon, melanoma.
What are the associated sonographic characteristics of benign thyroid lesions? 5
- Regular
- Well-defined borders
- Thin hypoechoic halo
- Hyperechoic
- Large calcifications around the periphery.
What are the associated sonographic characteristics of malignant thyroid lesions? 3
- Irregular borders
- Absence of a halo
- Microcalcifications.
