Thyroid, Parathyroid A&P Pathophysiology (incomplete) Flashcards
what increased iodide uptake
thyroid stimulating hormone
what helps to inhibit the production of TSH in a negative feedback loop
somatostatin
what is the middle portion of the thyroid gland that connects the two lobes called
isthmus
what is the blood supply to the thyroid gland
superior thyroid artery - off external carotid
also from inferior thyroid after (off of the thyrocervical trunk from the suprascauplar artery)
what innervates the thyroid gland
recurrent laryngeal nerve - branch off the vagus nerve (CN X)
how much hormone does the thyroid store
2-3 months worth
what is the thyroid gland made up of
follicular cells surrounded by colloid
follicular cells are sites for binding of TSH and trigger release of stored TH
can also be neurally controlled by acetylcholine and catecholamines
what is the active form of TH
triodothyronin (T3)
what is made within the follicular cell
thyroglobulin - large protein that contains significant amount of tyrosine amino acids - stored in colloid
what is able to oxyidize the iodide into active form of iodine
thyroid peroxidase
what is the advantaged of T4
longer half life
where is iodide aborbed
in the GI tract
what is thyroid hormone bound to within the blood stream
thyroxine binding globulin
small amount bound to albumin
is thyroid hormone water soluble or lipid soluble
lipid soluble
what are the actions of thyroid homrone
changing ion channel regulation
increase protein catabolism
increase number and size of mitochondria
stimulate glucose metabolism which will increase the basal metabolic rate and encourage glucose uptake, glycoysis
increases thermogenesis
what is primary hyperthyroidism
elevated thyroid hormone (T3 and T4), low thyroid stimulating hormone (does not need to stimulate the thyroid for the elevated production)
what is seen on labs with secondary hyperthyroidism
elevated TH, elevated TSH (excess being production/secreted in the pituitary)
what is thyrotoxicosis
symptomatic elevation in circulating thyroid hormone (hyperthyroidism)
Major primary cause of this is Graves disease
what is the secondary cause of thyrotoxicosis
(not as common) active TSH pituitary adenoma
What is an autoimmune disorder that causes 50-80% of hyperthyroidism
Graves disease
what are the ophthalmologic manifestations of graves disease
lid lag (both upper and lower)
exophthalmos: inflammation, edema, too much content in the orbit
what is the dermatologic manifestations of Graves disease
pretibial myxedema - aka graves dermopathy
what causes pretibial myxedema
thryoid stimulating immunoglobulins causing increased stimulation of T lymphocytes
increased hyaluronic acid production
swelling/induration/erythema to anterior lower extremities
when do nodular thyroid diseases occur
during stressor - typically will normalize after stressor
what is the presentation of hyperthyroid
heat intolerance
sweating
weight loss
diarrhea
weakness
psychiatric disorders
fatigue but inability to sleep
excitable
what is the most common disorder of the thyroid
hypothyroidism
what is primary disease state of hypothyroidism
low thyroid hormone (T3 and T4), high thyroid stimulating hormone (trying to up regulate to TH)
what is secondary disease state of hypothyroidism
low TH, low TSH ( the low TSH is causing the low TH) - associated with trauma, lesions, CVA
what is the most common type of hypothyroidism worldwide
deficiency
what is Hashimoto disease
an autoimmune thyroiditis - hypothyroidism
what does the central cause of hypothyroidism lead to
decreases TRH and/or TSH
what is Sheehan syndrome
necrotic pituitary from postpartum syndrome
what is the presentation of hypothyroidism
cold intolerance, fatigue, low body temp
weight gain, decreased appetite, bradycardia, constipation, fatigue, dry skin, thin nails
may lead to goiter
what is central hypothyroidism
damage to hypothalamus leading to decrease TRH or damage to the anterior pituitary leading to decreased TSH
what are labs indicative of hypothyroidism
low TSH
low T3
low T4
what is an autoimmune thyroiditis with autoantibodies attaching follicular cells
hashimotos thyroiditis
if someone has primary hypothyroidism what are their labs going to show
High TSH
Low T3 and T4
what can Graves disease develop into
Hashimotos
what is Hashitoxicosis
as cells undergo apoptosis it can cause transient hyperthyroidism (so many hormones released all at once)
what is myxedema
prolonged significant hypothyroidism - typically near zero TH
what is myxedema coma
rare and often fatal condition associated with untreated, longstanding hypothyroidism in which the body has not been able to compensate - no true coma
what is the presentation of myxedema coma
AMS
HTN
dry, cool skin - hypothermia
constipation, distension - illeus, impaction, myxedema megacolon
hypoventilation
arrhythmias, heart block
facial changes
nonpitting edema
acquired von willebrand syndrome
what is cretinism
occurs with profoundly low thyroid hormone during development, infancy or early childhood
what is cretinism associated with
agenesis or under developed
mom will supply some in utero
how do you treat cretinism
iodine and T4 - will lead to normal growth
what is an abnormal cellular growth of the thyroid
goiter
what can thyroid goiters be associated with
inability to trap iodide
not enough peroxidase so that iodine can not be oxidized into iodine
lack of or defective thyroid peroxidase (unable to go through final steps of TH formation)
what does the parathyroid release
parathyroid hormone which regulates calcium concentration
what cells are the primary creator of the parathyroid hormone
chief cells
is PTH water or lipid soluble
lipid soluble?
what triggers the release of PTH
hypocalcemia
what does PTH first trigger
inhibition of osteoblasts
what does PTH work with
vitamin D to allow for absorption in GI tract
what activates vitamin D
kidney and liver
when can the parathyroid gland enlarge in live
during pregnancy and breast feeding
what are the action of PTH in the kidney
bind to cell within distal collecting duct
– increase in calcium channels to cause respiration of Ca2+ from urine, will cause increased phosphate excretion
what are the actions of PTH in the intestine
induces the conversion of Vitamin D to active vitamin D - allows for absorption in GI tract
what type of hormone is vitamin D
steroid hormone
what secreted calcitonin
thyroid has C cells - to lower calcium levels in blood
what is the purpose of calcitonin
decrease circulating Ca2+
what is the most common cause of hyperparathyroidism
solitary parathyroid adenoma
what is secondary hyperparathyroidism
elevated PTH but b/c of low Ca2+
- typically associated with CKD or vitamin D deficiency
what is seen with hyperparathyroidism
elevated PTH
hypercalcemia
hypophosphatemia (causes increased renal excretion)
elevated phosphate in urine
elevated calcium in urine
what are the signs of hyperparathyroidism
elevated calcium: fatigue, nephrolithiasis, polydipsia, polyuria, N/V/D, abd discomfort, arrhythmia, osteoporosis, neurologic symptoms
what is seen with significant hypercalcemia
stones, bones, groans, moans and psychiatric overtones
-kidney stones, bone break down, constipation, pancreatitis, fatigue, psychiatric disturbances
what is the most common cause of Hypothyroidism
damage to the parathyroid*
-accidental removal with thyroidectomy
-neck radiation
-purposefully removed
what can you see with hypocalcemia
muscular tetani
Chvostek sign
Trousseau sign
AMS
prolonged QT
what is Chvostek sign
tap facial nerve anterior to the ear - causes facial twitch
what is Trousseau sign
BP cuff will cause carpal spasm - wrist flexion, MCP flexion, interphalangeal joint extension
