disorders of the thyroid - waldron Flashcards
what is the largest endocrine organ in the body
thyroid
what hormones does the thyroid produce
calcitonin
thyroxine (T4)
tri-iodothyronine (T3)
what makes up the thyroid
follicular cells
how is the thryoid hormone regulated
negative feedback loop
high TSH - is a slow thyroid
low TSH - fast thyroid
what is Goiter
an enlarged thyroid or abnormal growth of thyroid gland
depending on cause: may be associated with normal, decreased or increased thyroid hormone production
what is the most common causes of Goiter
worldwide: iodine deficiency
US: multi-nodular goiter, chronic autoimmune thyroiditis (Hashimoto’s), Graves disease
physiological (puberty/pregnancy), dysmorphogenesis (sporadic), radiation exposure, TSH release from pituitary gland, autoimmunity, infection, granulomatous disease
what types of food may affect thyroid function
broccoli, kale, cauliflower, peaches, strawberries, mustard, teas, red wine, soy products
what synthesizes the thyroid hormone
iodine
what is sporadic goiter
dysmorphogenesis and endemic goiter (iodine deficiency) mostly occur during childhood; thyroid gland increases more in size with age
what is the presentation of Goiter
most asymptomatic
swelling may be discovered incidentally
concern for compressive symptoms: dysphagia, dyspnea, hoarseness
may compress neck veins causing facial congestion, discomfort
pain is rare
what is seen on PE with Goiter
central neck swelling
cervical LA think malignancy: workup accordingly
vocal cord exam if hoarseness or before surgical intervention
pemberton maneuver
what is Pemberton maneuver
elevating arms may lift goiter into thoracic inlet and cause stridor, dyspnea or enlargement of neck veins
how do you workup/diagnose Goiter
TSH, free T4, T3
US to assess nodules - FNA cytology under US guidance
CXR
CT/MRI
radionuclide scanning
If a TSH below normal when Goiter is suspected what needs to be assessed next
check serum free T4 and T3
- hyperthyroidism: graves disease, multinodular goiter, toxic adenoma
if a TSH is above normal when Goiter is suspected what needs to be assessed next
check T3 and T4
hypothyroidism: hashimoto’s thyroiditis most likely, ecept areas of endemic goiter due to iodine deficiency
what is the usual TSH range
0.45 - 4.5
What is the treatment of non-toxic goiter
no tx: annual follow up
medical therapy is controversial
if intervention: usually surgery (thyroidectomy = mainstay tx)
radioiodine ablations
what is the etiology of hypothyroidism
autoimmune thyroiditis
previous thyroid surgery
radiation therapy
lithium
PTU
what is the etiology of hyperthyroidism
Grave’s disease
toxic nodule (toxic adenoma)
toxic multi-nodular goiter (Plummer’s disease)
thyroiditis
silent, post-partum, deQuervains thryoiditis (subacute)
what is the presentation of hypothyroidism
anorexia
fatigue, depression, lethargy
cold intolerance
constipation
dry, coarse hair
anemia
muscle stiffness and or cramps
memory impairment
bradycarida
hypo-reflexia
(slows them down)
what is the presentation of hyperthyroidism
nervousness
heat intolerance
sweating
increased appetite, weight loss (some gain)
loose stools
irritability/anxiety
fatigue
muscle weakness
tachycardia, afib, palpitations, PACs
hyper-reflexia
(speeds them up)
What is graves disease
most common cause of hyperthyroidism
autoimmune disease: usu +FHx, F>M, associated with HLA
precipitated by environmental factors: stress, smoking, infection, iodine, exposure, post-partum
TSH-receptor antibodies (TRAb) stimulate thyroid hormone production
what causes graves disease
thyroid stimulating immunoglobulin (TSI)
what stimulates TSH
TRab binding with TSH receptor on the thyroid
what causes hyperthyroidism and thyromegaly
TRab stimulating both thyroid hormone synthesis and thyroid gland growth
What is the process of Graves (toxic goiter, thyrotoxicosis)
stimulating antibodies to TSH-R (TRab) -> diffuse enlargement of thyroid gland -> increasing levels of thyroid hormones suppress TSH at anterior pituitary -> low TSH, normal or high T3, T4
What is the presentation of Graves disease
most patients present with signs and symptoms of hyperthyroidism
rare presentation of graves orbitopathy (TED)
depends on age of onset, severity, duration
how do the elderly present with graves disease
symptoms may be subtle/masked
may have non-specific: fatigue, weight loss, new onset Afib
atypical: “apathetic thyrotoxicosis”
what is the presentation of younger patients with graves disease
common presentation: heat intolerance, sweating, fatigue, weight loss, palpitation, hyperdefecation, tremors
other possible: insomnia, anxiety, hyperkinesia, dyspnea, muscle weakness, pruritus, polyuria, loss of labido
eyes: lid swelling, ocular pain, conjunctival redness, dipolopia
what are physical signs of hyperthryoidism
tachycardia, HTN with increased PP, signs of heart failure, afib, fine tremors, hyperkinesia, hyperreflexia, warm/moist skin, palmar erythema, hair loss, diffuse palpable goiter, AMS
what are the extrathyroidal manifestation signs
thyroid eye disease
marked thickening of skin, mainly over tibia
bone: sub-periosteal bone formation and swelling in metacarpal bones
onchyolysis (plummer nails), clubbing: rare
what is thyroid storm
sudden on set with severe symptoms of thyrotoxicosis
medical emergency - high mortality rate d/t cardiac arrhythmias
HTN, tachy, fever, mental status changes, N/V/D
what is graves ophthalmopathy
proptosis, conjunctival irritation, eye pain, eye dryness, double vision -> refer to ophtho
how do you diagnose/work up graves disease
most pts: usually clear signs/symptoms
diagnostic tests: TSI, TSH (low), T3 and T4 (elevated), TRab (elevated), tyroid radioavtive iodine uptake (i131), US to assess thyroid BF, CT/MRI of orbits
what is the treatment of hyperthyroidism
consider endocrine referral (strongly)
medications: propylthiouracil (PTU), methimazole
-radioactive iodine (RAI) tx
-total thyroidectomy
propranolol PO -supportive until thyrotoxicosis is resolved
what is the recommended first line treatment for graves disease
radioactive iodine
advantages: permanent resolution, non-invasive
disadvantages: results in hypothyroidism, delay of onset (6-8weeks)
when is radioactive iodine contraindicated
pregnant or breast-feeding women
what is the advantages/disadvantages of thiourea drugs (propylthiouracil (PTU) or methimazole)
weeks to control hyperthryoidism, usu. 12-24 months
advantages: if spontaneous resolution, now euthyroid on no meds
dis: difficult to control thyroid hormone levels, neurotpenia, liver enzyme elevation, rash, arthralgia, possibility of relapse
what is the drug of choice for graves disease with pregnancy
PTU (propylthiouracil)
what are the advantages/disadvantages with total thryoidectomy
advant: fast resolution of hyperthyroidism
dis: invasive, full anesthesia, post-op hypothyroid
consider in pregnant women intolerant to PTU
what is the treatment of thyroid storm
referral to endocrine via ER
block thyroid hormone action: beta blocker
block thyroid hormone release and conversion from T4 to T3:
- PTU, postassium iodine, ipodate sodium (iodinated contrast), hydrocortisone IV
supportive
What is Plummers disease
toxic nodular goiter (TNG)
autonomously functioning thyroid nodules, with resulting hyperthyroidism
second most common cause of hyperthyroidism in western world
What is the pathophysiology of TNG
spectrum of single hyperfunctioning nodule (toxic adenoma) within a multinodular thyroid to a gland with multiple areas of hyperfunctioning
hyperthyroidism usu. occurs with single nodules > 2.5cm in diameter
What is the Jod-Basedow effect
initial iodine supplementation can lead to hyperthyroidism
What is the epidemiology for TNG
W>M
women and men >40, prevalence rate of palpable nodule is 5-7% and 1-2%
most patients with TNG > 50yo
toxicity usu. peaks in 6th and 7th decade of life
what are the TNG thyrotoxic symptoms
signs of hyperthyroidism: heat intolerance, palpitations, tremor, weight loss, hunger, hyperdefication (usu. younger patients)
what are the symptoms for elderly patients with TNG
weight loss: m/c complain in elderly
anorexia and constipation
dyspnea or palpitations
tremor: may be confused with essential tremor
CV concerns: Hx AFib, HF, angina
what are obstructive symptoms of TNG
sx related to mechanical obstruction
large substernal goiter: dysphagia, dyspnea, or frank stridor - rarely a sx emergency
involvement of recurrent or superior laryngeal nerve may result in complains of hoarseness or voice change
what are the common lab findings with TNG
low TSH with NORMAL free T4
what is seen on PE with TNG
more subtle than graves
widended, palpebral fissues; tachycardia; hyperkinesis; moist, smooth skin; tremor; proximal muscle weakness; brisk DTR
what is a positive Pemberton sign
mechanical obstruction may cause SVC syndrome
what is the diagnosis/work up for TNG
thryoid function test
TSH: best initial screening tool; will be low
free T4: elevated or normal
nuclear scintigraphy (radioactive iodine - 123 - preferred)
US or CT neck
FNA
what is seen on nuclear scintigraphy with TNG
patchy with areas of increased and decreased uptake
what is the diagnosis/work up for TNG
thyroid function test
TSH: best initial screening tool; will be low
free T4: elevated or normal
nuclear scintigraphy (radioactive iodine - 123 - preferred)
when is FNA indicated for TNG
autonomously functioning (hot) thyroid nodule
dominant cold nodule present in mutinodular goiter
clinically significant nodule >1cm max diameter
non-palpable nodules; FNA with US assistance
what is the treatment for TNG
optimal tx remains contraversial
autonomously functioning nodules should be treated definitively with radioactive iodine or surgery
monitor
meds/surgery
endocrinology consult*
what are medication treatment options for TNg
anti-thyroid drugs (thioamides - PTU, methimazole) and beta blockers used for short courses
what is included within thyroiditis
spectrum of diseases: asymptomatic, hypothyroidism, with or without diffuse goiter, atrophic, occasionally painful, occasionally nodular, silent thyroiditis, postpartum thyroditis, thyrotoxicosis (rare)
What is Hashimoto’s thyroiditis
autoimmune dx that destroys thyroid cells by cell and antibody-mediated immune process
aka chronic autoimmune thyroiditis and chronic lymphocytic thyroditis
formation of anti-thyroid antibodies that attack thyroid tissue causing progressive fibrosis
what is the m/c lab findings with hashimotos thyroiditis
elevated TSH, low free thyroxine (T4), increased anti-thyroid peroxidase (TPO) antibodies
what is the most common cause of hypothyroidism in iodine -suffieicne world (after age 6)
hashimotos thyroiditis
what is the conventional treatment of Hashimotos
levothyroxine at 1.6-1.8 mcg/kg/day
what is the patho of hashimotos thyroiditis
autoimmune origin with lymphocyte infiltration and fibrosis
current dx based on clinical symptoms with lab results of elevated TSH and normal to low T4
what is the presentation of hashimotos
initially hyperthryoid sx
skin: myxedma (dry and brittle hair and skin)
cardiac: increased PVR, bradycardia, most present with pre-existing CV conditions
fatigue, exertional dyspnea, exercise intolerance
muscle weakness and myopathy
what are the early symptoms of Hashimotos
constipation, fatigue, dry skin, weight gain
what are teh advanced symptoms of hashimotos
cold intolerance, decreased sweating, nerve deafness, peripheral neuropathy, decreased energy, depression, dementia, memory loss, muscle cramps, joint pain, hair loss, apnea, menorrhagia, pressure symtpoms in neck
what are urgent presentation concerns with hashimotos
accumulation of fluid in pleural and pericardiac cavities: admission and drainage
myxedema coma is the most severe clinical and must be managed as medical emergency
what is the workup for hashimotos
TSH- slightly increased to high
T3 and T4 - low
positive anti-TPO and TGab
US and radioactive iodine untake helps distinguish from graves
FNA if malignancy concern
CK, prolactin, total cholesterol, LDL, TG - usu. elevated
what is the mainstay of treatment for hashimotos/hypothyroidism
thyroid hormone replacement
DOC: Titrated levothyroxine sodium PO QD
half life of 7 days - early morning on empty stomach
what should be avoided when taking titrated levothyroxine sodium
iron or calcium supplements, aluminum hydroxide, proton pump inhibitors, grapefruit or orange juice: causes suboptimal absorption
what are other treatment options for hypothyroidism
crtomel (liothyronine) - synthetic T3
armour thyroid (“biologic thyroid replacement”)
What is Myxedema coma
extreme form of hypothyroidism - medical emergency, rare, high mortality
clinical dx
what is the presenatation of myxedema coma
weakness, stupor, hypoventilation, hypothermia, hyponatremia, shock and death
what is the treatment of myxedema coma
ICU admission, IV levothyroxine, supportive care for respiratory and fluid status
What is chronic autoimmune gastritis (CAG)
partial or complete loss of parietal cells leading to impairment of hydrochloric acid and intrinsic factor production
develop iron-deficient anemia (micro), leading to pernicious anemia (macro), then severe gastric atrophy
What is Cretinism
iodine deficiency
What is congenital hypothyroidism from Cretinism
due to a deficiency in thyroid hormone during early fetal development (maternal hypothyroidism during preg), usu. secondary to iodine deficiency
What determines iodine deficiency
iodine intake chronically < 20 /day
what are signs and symptoms of congential hypothyroidism
intellectual disability, deaf, mute, gait disturbances, short stature, puffy hands and feet, spasticity
what are diagnostic tests for thyroid nodule
thyroid ultrasound, TSH, T4
if TSH low: thyroid uptake and scan
if nodules > 0.6cm, strongly consider biopsy
what are the most common thyroid cancers
papillary thyroid cancer (m/c)
follicular thyroid cancer
medullary thyroid cancer
anaplastic thyroid cancer (ATC) (RARE)
what are the risk factors for developing thyroid cancer
F>M
radioactive iodine exposure, fhx, childhood head and neck radiation (20-25 years later)
what is the clinical presentation of thyroid cancer
painless neck swelling
non-tender firm nodule
hoarseness
neck discomfort
dysphagia (compressive symptoms)
palpable thyroid nodule, gland may be stony and hard
single nodule
how do you diagnose/work up thyroid cancer
contingent on cytologic or histologic findings on biopsy
childhood radiation hx
TSH, T3, T4, TSH may be normal (t3/4 may be elevated)
US - anatomic eval - best first step
i131 uptake study= functional evaluation
FNA
what is the treatment of thyroid cancer
surgical resection
RAI ablation
TSH suppression
What is the treatment for ATC CA
little to no role for surgery - local invasion into trachea or vasculature - unresectable
5 year mortality near 100%
what are complications of thyroid cancer
locally invasive if untreated - airway, esophagus or neurovascular structures
metastatsis: lung, bone, soft tissue
surgical complications
