DMS 240- Unit 1

Pyramidal lobe

Arises superiorly from the isthmus

Larger

Females typically have a _________ thyroid gland than men

6mm L×2mm AP×2mm TRV

Typical thyroid measurements

Structures in carotid sheath

• Vagus nerve

• Carotid a.

• Internal jugular v.

Function of the Thyroid

• Metabolism

• Synthesis, storage, and secretion of thyroid hormones

• Iodine metabolism to create thyroid hormones

Colloid

Common benign nodule in the thyroid, storage for thyroid hormones Iodine metabolism, contains fluid produced by the thyroid

Strap muscles

Sternohyoid, sternothyroid, omohyoid

Sternohyoid

A strap muscle, “higher” than the rest, located anterior to the thyroid

Sternothyroid

A strap muscle, located immediately superoior/lateral to the thyroid

Omohyoid

A strap muscle, located lateral to the sternothyroid muscle

Left

The esophagus is located slightly to the ______

Arteries supplying the thyroid

• 2 superior thyroid arteries

• 2 inferior thyroid arteries

Superior thyroid a.

These arteries are a branch of the external carotid arteries

Internal jugular vein

The superior/mid thyroid veins drain to the __________ _______ _____

Innominate vein

The internal jugular vein drains inferiorly to the ___________ _____

T3

Triiodothyronine

T4

Thyroxine

• Most abundant hormone secreted by the thyroid

Calcitonin

• Secreted by c-cells of the thyroid

• Inhibits breakdown of bone matrix and increases formation of bone- decreases blood levels of calcium

Euthyroid

Normal thyroid function

Hypothyroidism

Under secretion of thyroid hormones

• Caused by low iodine intake, malfunctioning thyroid, malfunctioning pituitary

Sx of hypothyroidism

Weight gain, hair loss, lethargy, intellectual/motor slowing, excess sub Q around eyes, cold intolerance, constipation, deepening of voice

Hyperthyroidism

Over secretion of thyroid hormones

• Caused by loss of thyroid gland control or localized neoplasm causes overproduction

Sx of Hyperthyroidism

Weight loss, increased appetite, nervous energy, tremor, excessive sweating, heat intolerance, palpitations, exphthalmos

Hyperthyroidism typical lab values

Decreased TSH, increased T3 & T4

Hypothyroidism typical lab values

Increased TSH, decreased T3 & T4

Uptake

Nuc med tracks the _________ of iodine

Thyroid normal sonographic appearance

“Headphone” or “earmuff” shape, typically hyperechoic to surroundings hypoechoic muscles, smooth homogenous fine echotexture

Lymphnode normal sonographic appearance

Blob shaped, well defined borders with hyperechoic hilum and hypoechoic cortex, should have stalk with color dopp

< 1 cm

Normal lymphnode thickness

< 3-4 mm

Normal lymphnode cortex thickness

Signs of abnormal lymphnode

Rounded appearance, loss of hyperechoic center, increased cortex thickness, vascularity throughout node instead of the stalk

Pressure

Too much _________ from the TRX on the neck can impede blood flow in a lymphnode

Goiter

Any enlargement of thyroid gland

• Most common abnormality

• Hypertrophy and hyperplasia due to hampered hormone secretion

Types of goiter

Graves’ disease, thyroiditis, neoplasm, cyst

nodular

Goiter can appear diffuse and symmetric or irregular and _________

Nontoxic goiter

Goiter in which thyroid hormones remain in normal range

• NOT caused by nodule or neoplasm

Toxic goiter

Goiter in which thyroid hormones are elevated

1st stage simple Goiter

Enlargement from compensation of TSH for lack of iodine causing hyperplasia

2nd stage simple Goiter

Gland begins to lag, colloid involution leads to multinodular gland, resulting in hemorrhage, calcification, and asymmetry

Multinodular

All long standing simple goiter coverts to _____________ goiters

Toxic multinodular goiter sonographic appearance

Enlarged thyroid, inhomogenous, focal scarring, focal areas of ischemia, necrosis, cyst formation, fibrosis, calcifications, may have halo appearance around nodules, asymmetric

Graves’ disease

Thyroid inferno (gets name from hypervascular flow)

• Diffuse toxic goiter

• Cutaneous manifestations (Thickened tissue, common on legs and feet)

• Autoimmune disorder

• Hyperplastic thyroid with hyperemic flow

Thyroiditis

Inflammation of the thyroid

• From either infection or autoimmune process

Types of Thyroiditis

De Quervain’s, Hashimotos, Reidel’s

De Quervain Thyroiditis

Thyroiditis caused from viral infection

• Diffuse inflammation

• Gradual to relatively abrupt onset

• Transient hyperthyroidism (may produce excess and goes back to normal function)

Hashimoto’s Thyroiditis

Most common form of inflammation of the thyroid

• Autoimmune disease

• Progresses to a severely damaged gland with hypothyroidism

• Normal or increased in size, irregular surface heterogenous in echotexture

Riedel’s Thyroiditis

Rare, fibrous thyroiditis

• Progressive, chronic

• Enlarged thyroid, fixed and hard