Thyroid & Parathyroid Glands Flashcards
what is the thyroid’ job
maintains metabolism, growth, and development
synthesizes, stores, and secretes hormones through tissue/blood not ducts
function - control BMR (basil metabolic rate)
the thyroid/parathyroid are in what system of the body
largest endocrine gland in the body
the thyroid is located in the ___________ neck at the level of the thyroid cartilage
anteroinferior
how many lobes does the thyroid have
2 - left and right
what connects the 2 lobes of the thyroid
the isthmus
the thyroid straddles the ________ anteriorly
trachea
the thyroid is bounded laterally by the _______ arteries and _______ veins
carotid arteries
jugular veins
_______ _______ arises from the isthmus
pyramidal lobe
the thyroid develops prenatally in the _____ week
3rd
_________ duct connects thyroid to the tongue
thyroglossal
thyroglossal duct atrophies by the _____ week
8th
if thyroglossal duct persists what might form
cyts, fistulas, accessory pyramidal lobe** (15-30%)
extends superiorly from isthmus
can be considered ______ tissue
ectopic
what is the shape of the thyroid
U or H shape
thryroid varies with what 3 things
age, gender, and body surface
what lobe is usually larger, right or left
right lobe
do females or males have larger thyroids
females
lobes = ______
size
what is the normal size of an adult thyroid
4-6 cm long x 1.3-1.8 cm AP x 1.5-2 cm wide
what is the normal size of the isthmus
2-6 mm
what is anterior to the thyroid
strap muscles
sternocleidomastoid muscle
what is posterolateral to the thyroid
important
CCA
IJV
longus colli muscle
what is medial to the thyroid
larynx
trachea
esophagus
what are the 3 strap muscles
sternohyoid
omohyoid
sternothyroid
the thyroid is _____ vascular
highly
2 _____ _____ arteries from ECA descend to upper poles
superior thyroid
2 ______ ______ arteries from subclavian and ascend to lower poles
inferior thyroid
corresponding veins drain into the ______ vein
IJV (internal jugular vein)
what is the first branch off the ECA
superior thyroid
______ is processed by follicular cells to manufacture, store, and secrete thyroid hormones
iodine
the thyroid gland traps iodine from _____ and through a series of _____ reactions
blood
chemical
trapping iodine produces which thyroid homones
T3 (triiodothyronine) and T4 (thyroxine)
when thyroid hormone is needs by the body, it is released into the bloodstream by action of thyrotropin, or ______-______ hormone, produced by pituitary gland
thyroid - stimulating hormone (TSH)
_______ decreases concentration of calcium in blood by first acting on bone to inhibit its breakdown
calcitonin
calcitonin helps to maintain what
homeostasis of blood calcium
secreted by C-cells or parafollicular cells
what is the most potent hormone
T3 - triiodothyronine 10%
thyroid produces 90% of which hormone
T4 - thyroxine
hormones are stored in the _____
colloid
the pituitary produces what hormone
TSH
secreation of TSH is controlled by what….what produces with hormone
TRH
hypothalmus
what is euthyroid
the correct amount of hormone production
what is hyperthyroidism
increased amount of hormone production
what is hypothyroidism
decreased amount of hormone production
describe hypothyroidism
undersecretion of hormones low intake of iodine inability of thyroid to produce thyroid hormones chronic autoimmune thyroiditis pituitary gland or hypothalamus disease
some clinical signs of hypothyroidism
weight gain hair loss increased tissue around eyes lethargy cold intolerance dry skin bradycardia
sonographic appearance of hypothyroidism
diffusely abnormal decreased heterogeneous echogenicity normal enlarged with irregular surface small calcifications
describe hyperthyroidism
oversecretion of thyroid hormones
entire gland out of control
Graves’ disease
toxic adenomas
clinical signs of hyperthyroidism
dramatic increase in metabolic rate weight loss with increased appetite nervous energy tremors excessive sweating tachycardia exopthalmos - bulging eyes & retraction of eyelids
sonographic appearance of hyperthyroidism
normal sized or enlarged gland
inhomogeneous
hypervascularity - key sign for Graves’ disease
describe thyroid functioning tests
nuc med
blood tests to measure T3 & T4
describe “hot” nodules on nuc med tests
hyperfunctioning nodule
5-10% of all nodules - usually benign
describe “cold” nodules on nud med tests
nonfunctioning
80-85% of all nodules - 10-15% of these are malignant
what is an important part to do before scanning the thyroid
get patient’s history
how should a patient lay for a thyroid scan
supine positioning with pillow under shoulders for hyperextension of neck
what tranducer is used to scan a thyroid
high frequency linear
each lobe is imaged in ______ and ______ planes
make sure you also image the ______
long and trans
isthmus
transverse sono landmarks
CCA
IJV
trachea
Longitudinal sono landmarks
should extend lateral to include region of CCA
the thyroid has what kind of echotexture
fine homogeneous
vessels will be seen as ______ tubular structures
anechoic
muscles with appear as _______
hypoechoic
what should be documented during a thyroid scan
define texture (solid, cystic, or complex)
single/multiple
location
evaluate adjacent lymph adenopathy
US is also used for _________ procedures of the thyroid
interventional
what is the most common cause of thyroid disorders world wide
iodine deficiency
what does iodine deficiency lead to
goiter formation
hypothyroidism
_________ processes responsible where iodine is not deficent
autoimmune
autoimmune processes can lead to what
hypothyroidism
hyperthroidism
describe a goiter
diffused enlargement of thyroid peak age 35-50 yrs females 3:1 80% is caused by hyperplasia of the gland hampers hormone secretion may become very large endemic goiter
what are the types of goiters
nodular hyperplasia
multinodular goiter
adenomatous hyperplasia
simple/non-toxic - no functional disturbance/happens in puberty
multinodular/toxic - increased/decreased function
causes of goiters
iodine deficiency thyroid hormone deficiency Graves' disease thyroiditis neoplasm cyst
describe non-toxic (simple) goiter
diffuse uniform enlargement
iodine deficiency
dietary shortage or gland malfunction
may lag behind = hypothyroidism
describe toxic multinodular goiter
may be spontaneous may be end stage of simple goiter enlarged heterogeneous focal scarring, ischemia, necrosis, cyst formation, calcifications asymmetry
describe Graves’ disease
female > 30
autoimmune
most frequent cause of hyperthyroidism
what is the Graves’ disease triad
triad - diffuse toxic goiter, exopthalmos, dermis thickening
Graves’ disease sonographically
hypoechoic
diffuse homogeneous enlargement
increased color flow
what is the to go word for Graves’ disease
important
“thyroid inferno”
due to increased color flow
describe thyroiditis
swelling and tenderness
infection or autoimmune
what are the 2 types of thyroiditis
De Quervain’s - viral infection
Hashimoto’s - destructive autoimmune disorder
describe De Quervain’s
subacute granulomatous thyroiditis fever enlarged gland pain on palpation pain may radiate to ear or jaw
describe Hashimoto’s
chronic autoimmune lymphocytic painless onset diffusely enlarged gland young to middle aged females heterogeneous as progresses & tenderness eventual severe gland damage = hypothyroidism - MOST COMMON
Hashimoto’s sonographically
hypoechoic coarse homogeneous thickened fibrous strands - chronic sign increased color flow - in acute stage over time - fibrotic, ill defined, heterogeneous increased risk for malignancy
what is the most common cause for US
palpable nodule
what is degeneration of follicular adenoma, may have debris
cysts
what are neoplasmic, complete fibrous encapsulation, females > males, many appearances commonly have peripheral halo, may cause hyperfunction
adenoma
describe cysts
10-15% of solitary nodules
common - colloid or degeneration or necrosis of adenomatous nodules
benign if < 4 cm
describe an adenoma
true benign neoplasm encapsulated solitary well defined females 7:1 most common thyroid neoplasm "cold" nuc med nodule
types of adenomas
embryonal fetal colloid follifular hyperplasic
describe carcinoma of the thyroid
rare
most common 40-60 yrs
risk of malignancy decreases with multiple nodules
sonographically - variable
**calcifications present 50-80% of all types
female 2:1
suspicious if single nodule seen & under 14 or over 65 yrs
describe papillary carcinoma
MOST COMMON - 75-90% 3rd & 7th decade of life female predominant thyroid cancer in children 25 % laminate calcifications 20% metastatic cervical adenopathy least aggressive
papillary carcinoma sonographically
hypoechoic
microcalcifications 90%
hypervascularity 90%
cervical lymph node metastasis 20%
describe follicular carcinoma
MORE AGGRESSIVE than papillary
females
solid nodule
metastases to lung, bone, and other distant sites
follicular carcinoma sonographically
irregular
firm
nodular enlargement
describe medullary carcinoma
5% thyroid cancers
hard bulky mass, enlargement
medullary carcinoma sonographically
bright echogenic foci within solid mass
what is medullary carcinoma associated with
elevated serum calcitonin
multiple endocrine neoplasm (MEN) type II
describe anaplastic carcinoma
rare
occurs after 50
MOST LETHAL
hard fixed mass with rapid growth
invades neck structures, causing death by compression & asphyxiation
6 mos - 1 yr lift expectancy
describe lymphoma
primarily non-hodgkin's type older females < 4% of all thyroid malignancies rapidly growing neck mass preexisting chronic lymphocytic thyroiditis - Hashimoto's
lymphoma sonographically
nonvascular hypoechoic mass
adjacent thyroid heterogeneous
what is the parathyroid anatomy
4 paired glands - (3-5) not uncommon
2 posterior superior poles, 2 posterior inferior poles
may be in neck/mediastinum
flat and disc shaped
parathyroid sonographic findings
not usually seen isoechoic to thyroid normal < 4 mm > 5 mm is enlarged, hypoechoic elongated masses between posterior longus colli & anterior thyroid
parathyroid physiology
calcium-sensing organs
produces PTH (parathyroid hormone)
when serum calcium decreased, PTH increased
PTH acts on bone, kidney, & intestine to enhance calcium absorption
unexplained hypercalcemia = US
describe primary hyperparathyroidism
increased function of the parathyroid glands
females
increased PTH from an adenoma, hyperplasia, or carcinoma
primary hyperplasia - hyperfunction with no apparent cause
describe secondary hyperparathyroidism
chronic hypocalcemia from renal failure, vit D def, malabsorption syndromes
compensatory reaction
leads to PTH stimulation
includes all 4 glands
primary hyperplasia - parathyroid
describe parathyroid adenoma
MOST COMMON cause of primary hyperparathyroidism 80%
can not discern adenoma from cancer
parathyroid adenoma sonographically
hypoechoic
solid
encapulated
discrete borders
neck masses: describe thyroglossal duct cyst
CONGENITAL anomaly
midline & anterior to trachea
remnant of tubular development
oval or spherical masses rarely larger than 2-3 cm
thyroglossal duct cyst sonographically
cystic mass anterior to trachea
neck masses: describe branchial cleft cysts
remnant of embryologic development
tract from pharyngeal cavity to auricle
results in cystic formation lateral to thyroid gland
may present with solid components, especially if infected
neck masses: describe abcesses
can be anywhere in neck
wide range of appearances
MOST COMMON low level echogenicity and irregular walls
describe adenopathy
shape of node should be oval homogeneous with central core echo complex more round - ? malignancy echo free node - ? inflammatory process fine needle aspiration to confirm
describe abn lymph nodes
loss of fatty hilum irregular margins cystic areas of degeneration calcifications round > 7 mm width or AP
