thyroid gland part 2

euthyroid

the state in which the thyroid is producing the right amount of thyroid hormone

hypothyroidism

undersecretion of thyroid hormones

hyperthyroidism

oversecretion of thyroid hormones

hypothyroidism may be caused by:

• low intake of iodine (goiter)

• inability of the thyroid to produce the proper amount of thyroid hormone

• a problem in the pituitary gland that does not control the thyroid production

in hypothyroidism, blood work will show:

• elevated TSH

• low T3 and T4

clinical signs and symptoms of hypothyroidism:

• weight gain and water retention (myxedema)

• hair loss

• cold intolerance

• constipation

• fatigue

• goiter

• deep husky voice

treatment of hypothyroidism:

thyroid hormones can reverse the condition

hyperthyroidism may be caused by:

the entire gland being out of control or if localized neoplasm causes overproduction of the thyroid hormone

in hyperthyroidism, blood work will show:

• low TSH

• elevated T3 and T4

clinical signs and symptoms of hyperthyroidism:

• increased metabolic rate-weight loss

• increased appetite

• high degree of nervous energy

• tremor

• excessive sweating

• heat intolerance

• exophthalmos (protruding eyes)

treatment of hyperthyroidism:

• antithyroid medicine

• radioactive iodine

• thyroidectomy in rare cases

nuclear medicine

• used to determine the function of the thyroid

• a small amount of radioactive iodine is injected into the bloodstream

after radioactive iodine is injected, if a greater percentage is taken up, this indicates:

an area of hyperfunctioning (hot nodule)

after radioactive iodine is injected, if a smaller percentage is taken up, this indicates:

an area of hypofunctioning (cold nodule)

what is the most common cause of thyroid disorders worldwide?

iodine deficiency

nodular thyroid diseases:

• goiter

• Graves disease

• thyroiditis

goiter

• most common thyroid abnormality

• enlargement of the thyroid gland which is often visible on the anterior neck

nontoxic simple goiter

occurs as diffuse thyroid enlargement not resulting from a neoplasm or inflammation

sonographic appearance of a nontoxic simple goiter:

• enlargement of thyroid gland

• sometimes smooth

• sometimes nodular

• one side may enlarge more than the other

• compression of the surrounding structures may be noted

toxic multinodular goiter

hyperthyroid condition resulting from hyperactivity which produces a large nodular gland

sonographic appearance of a toxic multinodular goiter:

• multiple nodules may demonstrate halos and may have clear or non-discrete borders

• the solid portion of the lesions may have the same echotexture as the normal thyroid tissue

• calcifications and cystic areas may be present within nodules

Graves disease

• occurs more frequently in women greater than 30 and is related to an autoimmune disorder

• characterized by thyrotoxicosis and is most frequent cause of hyperthyroidism

Graves disease is characterized by a triad of the following findings:

• hypermetabolism

• diffuse toxic goiter

• exophthalmos

• cutaneous manifestations

sonographic appearance of Graves disease:

• gland is diffusely homogeneous and enlarged

• gland appears hypoechoic with diffuse enlargement without palpable nodules

• doppler shows increased vascularity

thyrotoxic crisis (thyroid storm)

• an acute situation in a patient with uncontrolled hyperthyroidism, usually precipitated by infection or surgery

• may be life threatening because of resulting hyperthermia, tachycardia, heart failure and delirium

thyroiditis

• usually found in middle-aged women

• caused by infection or can be related to autoimmune abnormalities

sonographic appearance of thyroiditis:

the gland appears normal or enlarged in size, hypoechoic and may have an irregular surface

clinical symptoms of thyroiditis:

thyroid is enlarged, tender and pt may have a fever

what are the 2 types of thyroiditis?

• de Quervain’s

• Hashimoto’s

subacute (de Quervain’s) thyroiditis

usually caused by a viral infection of ht thyroid, which results in diffuse inflammation of the thyroid with enlargement and tenderness

Hashimoto’s thyroiditis

• most common form of thyroiditis

• most common cause of hypothyroidism

• characterized by a destructive autoimmune disorder which leads to chronic inflammation of thyroid

sonographic appearance of Hashimoto’s thyroiditis:

inhomogeneous pattern with overall decreased echogenicity of the gland

types of benign lesions:

• colloid cysts

• adenomas

thyroid cysts

usually caused by trauma or degeneration of an adenoma

sonographic appearance of complex cysts:

• blood or debris may be present within them

• cystic mass with irregular borders that may have multiple septations and/or low-level internal echoes

sonographic appearance of hemorrhagic cysts:

purely anechoic areas result from serous or colloid fluid, echogenic fluid or moving fluid/fluid levels

sonographic appearance of simple cysts:

• anechoic

• sharp, well-defined walls

• distal acoustic enhancement

adenoma

• most common nodule occurring in the thyroid

• may be singular or multiple

sonographic appearance of adenomas:

• well-defined round or oval mass that varies in size

• varied echogenicity

• usually solid masses which often have an anechoic halo (thin echolucent/hypoechoic rim surrounding the lesion)

• calcification (calcific rim) may be present and an acoustic shadow may be seen posteriorly

sonographic appearance of a hemorrhagic adenoma:

• very hyperechoic

• looks “fluffy” like a cotton ball

types of malignant lesions:

• papillary carcinoma

• follicular carcinoma

• medullary carcinoma

• anaplastic (undifferentiated) carcinoma

• lymphoma

sonographic appearance of malignant thyroid lesions:

• lesion can be of any size, single or multiple, and can appear as solid, partially cystic, or largely cystic masses

• calcifications are often present

papillary carcinoma

• most common thyroid malignancy

• the predominant cause of thyroid cancer in children

sonographic appearance of papillary carcinoma:

• hypoechogenicity

• microcalcifications that appear as tiny hyperechoic foci

• hypervascularity

follicular carcinoma

more aggressive tha papillary cancer

sonographic appearance of follicular carcinoma:

• usually a solitary mass

• irregular, firm, nodular enlargement

medullary carcinoma

presents as a hard, bulky mass that causes enlargement of a small portion of the gland and can involve the entire gland

sonographic appearance of medullary carcinoma:

• lesions appear as punctuated, bright, echogenic foci within solid masses

• these masses correspond pathologically to deposits of calcium surrounded by amyloid

anaplastic (undifferentiated) carcinoma

• usually occurs after 50 yrs of age

• lesion manifests as a hard, fixed mass with rapid growth

• growth is locally invasive into surrounding neck structures

lymphoma

• non-Hodgkin’s type

• can be associated with Hashimoto’s

• pt presents with a rapidly growing mass in the neck area

sonographic appearance of lymphoma:

• nonvascular and lobulated mass

• large areas of cystic necrosis may be present within tumor or encasement of adjacent neck vessels

• the adjacent thyroid parenchyma may be heterogeneous secondary to associated chronic thyroiditis