Thyroid Flashcards
The thyroid is part of the
endocrine system
The thyroid maintains what 3 things
metabolism, growth, and development
Produces, stores, and secretes what hormones
Triiodothyroinine (T3)
Thyroxine (T4)
Calcitonin
Thyroid is located in the ____ neck
anteriorinferior
Size of thyroid and isthmus
Adult Thyroid Length: 4-6cm
Isthmus: 0.4-0.6cm
Child Thyroid Length: 2-3cm
Blood is supplied by what 4 arteries
Two superior thyroid arteries arise from the ECA
Two inferior thyroid arteries from the thyrocervical trunk of the subclavian artery
The mechanism for producing thyroid hormones is
iodine metabolism
The thyroid traps iodine from the blood and, through chemical reactions produces what
T3 and T4
When the body needs thyroid hormone , it is released into the bloodstream by the action of what
thyrotropin also known as thyroid-stimulating hormone (TSH)
TSH is produced by the
pituitary gland
____ decreases the concentration of calcium in the blood
Calcitonin
Hypothyroidism
Under secretion of the thyroid hormone
Clinical signs and symptoms of Hypothyroidism
Myxedema-swelling and thickening of the skin Weight gain Hair loss Increased subcutaneous tissue around the eyes Lethargy Intellectual and motor slowing Cold intolerance Constipation Deep husky voice
Causes of Hypothyroidism
Low intake of iodine (goiter) in the body
Inability of the thyroid to produce adequate amount of the thyroid hormone
A pituitary gland that does not control the thyroid production
Over secretion of the thyroid hormone
Hyperthyroidism
Clinical signs and symptoms of Hyperthyroidism
Weight loss Increased appetite High amount of nervous energy Tremor Excessive sweating Heat intolerance Palpitations Exophthalmos (Protruding eyes)
The most common cause of thyroid disorders worldwide
iodine deficiency
Enlargement of the thyroid gland that is often visible as an anterior protrusion of the neck
Goiter
Causes of Goiter
Graves’ disease
Thyroiditis
Neoplasm
Cyst
Goiter Sonographic Findings
Enlarged, nodular and appearance may vary
Overall heterogeneous thyroid
Isoechoic to hyerechoic nodules
Thin peripheral halo as a result of perinodular blood vessels and edema
Fibrosis and calcifications may develop
Ultrasound is used to determine the location and characteristics of the masses
Adenoma
Follicular adenoma is benign and characterized by complete fibrous encapsulation.
Types of malignant tumors
Papillary Follicular Medullary Anaplastic Lymphoma
Most common malignant tumor
Papillary carcinoma
Papillary carcinoma ultrasound findings
90% hypoechoic
Microcalcification with or without shadowing
90% hypervascular
Two types of Follicular Carcinoma
minimally invasive and widely invasive
Spreads through bloodstream rather than lymphatics
Follicular Carcinoma
Lymphoma ultrasound findings
Nonvascular Hypoechoic Lobulated Thyroid tissue may be heterogeneous because of associated thyroiditis Can have areas of cystic necrosis
Rapid growing neck mass
Lymphoma
Diffuse Thyroid Disease
Generally causes diffuse enlargement of the gland without palpable nodules
Conditions that cause diffuse enlargement
Graves/ disease
Thyroiditis
Colloid or adenomatous goiter
Types of Thyroiditis
Acute suppurative
Subacute (de Quervain’s)
Chronic lymphocytic (Hashimoto’s disease)
Characterized by thyrotoxicosis and is the most frequent cause of hyperthyroidism
Grave’s Disease
Most common type of thyroiditis
Hashimoto’s Thyroiditis
Hashimoto’s usually occurs in
Young or middle age female
Hashimoto’s ultrasound findings
Coarse and slightly more hypoechoic
Initially homogenous enlargement occurs with nodularity then progresses to inhomogeneous enlargement.
Parathyroid size
Normal size 4mm and not seen on ultrasound
Most common to have 4, but some have 3-5
Parathyroid produces what?
parathyroid hormone (PTH) and monitor serum calcium feedback mechanism
Patients with ______ are the most common referrals for parathyroid sonography.
unexplained hypercalcemia
Miscellaneous Meck Masses
Thyroglossal Duct Cyst
Brachial Cleft Cyst
Abscess
Lymphadenopathy
Causes of Secondary Hyperparathyroidism
Renal failure
Vitamin D deficiency (rickets)
Malabsorption syndromes
Secondary Hyperparathyroidism
Chronic hypocalcemia
Characteristics of Primary Hyperparathyroidism
Increase in function
Women two to three times more likely than men
Particularly common after menopause
Characterized by- hypercalcemia, hypercalcuiria and low serum levels of phosphate (hypophosphatasia)
Most are asymptomatic at time of diagnosis
Primary Hyperplasia
10% of primary hyperparathyroidism cases
Hyperfunction of all parathyroid glands with no apparent cause
Rarely > 1cm
Hyperplasia may or may not involve all glands
Adenoma
Most common cause of primary hyperparathyroidism 80% cases
Most common shape is oval, hypoechoic
Benign usually < 3cm
