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Clin Med Exam 3 > Thyroid > Flashcards

Thyroid Flashcards

1
Q

what is the main function of the thyroid?

A

helps regulate metabolism

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2
Q

what releases TRH?

A

hypothalamus when senses body needs T4/T3

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3
Q

what happens when the hypothalamus releases TRH?

A

TRH signals to anterior pituitary to secrete TSH

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4
Q

what releases TSH?

A

anterior pituitary

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5
Q

what happens when anterior pituitary releases TSH?

A

TSH tells thyroid to release thyroxine

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6
Q

what is the active form, T4 or T3?

A

T3

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7
Q

what converts T4 to T3?

A

iodine

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8
Q

what does a deficiency in iodine lead to?

A

a large thyroid b/c it keeps trying to produce the hormones, but there is no iodine there to convert it

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9
Q

what is thyrotoxicosis?

A

elevated unbound (“free”) thyroid hormone circulating in the body

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10
Q

what is the #1 cause of hyperthyroidism in the US?

A

Graves Disease

  • women>men
  • 20-40 y/o
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11
Q

what is Graves Disease

A

autoimmune disorder

  • increase and synthesis of release of both T4 and T3 from the thyroid
  • thyrotropin antibodies bind to TSH receptor to stimulate gland to keep secreting T4 and T3 (excess T4/T3)
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12
Q

what can exacerbate Graves disease?

A

Life stressors can exacerbate Graves Disease if patient is in remission

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13
Q

is Graves disease familial?

A

Yes, Familial tendency to get Graves Disease

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14
Q

other 2 causes of hyperthyroidism?

A

Toxic Multinodular Goiter (15-30%)

Toxic Nodular Goiter

-both are hyperplasia of thyroid cells that are functioning on their own (no feedback loops)

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15
Q

what type of adenoma can also cause hyperthyroidism? what are the levels of TSH like?

A

pituitary adenoma
-TSH/T4/T3 levels are high

(in hyperthyroidism, TSH is low)

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16
Q

common symptoms of hyperthyroidism?

A

Sweating, heat intolerance, palpitations, SOB (due to palpitations, weight loss (despite increase in hunger)

HYPERACTIVITY

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17
Q

what will you find on hyperthyroidism physical exam of skin/nails?

A

pruritus, moist skin, thinning hair, hyper pigmentation, onycholysis

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18
Q

what will you find on hyperthyroidism physical exam of HEENT?

A
  • lid lag and stare
  • opthalmopathy/exophthalmos
  • goiter or nodules
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19
Q

what will you find on hyperthyroidism physical exam of cardiac?

A

tachycardia/afib

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20
Q

what will you find on hyperthyroidism physical exam of neuro?

A

fine tremor and hyperreflexia

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21
Q

what else will you find on physical exam for hyperthyroidism?

A

Infiltrative Dermopathy raised hyperpigmented orange skin

Thyroid acropathy from prolonged hyperthyroidism – clubbing digits

Goiter with bruit

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22
Q

what is the mainstay of diagnosis for hyperthyroidism?

A

Labs!!!

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23
Q

when diagnosing hyperthyroidism what will the labs show?

A
  • TSH (decreased b/c a lot of T4/T3)
  • elevated T3/T4
  • antibodies (Anti-TPO, anti-thyrotropin receptor, thyroid-stimulating immunoglobulin)

(also decreased serum cholesterol & hypercaclcemia)

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24
Q

imaging studies for hyperthyroidism?

A

Nuclear scintigraphy w/RAIU (thyroid scan)
-thyroid scan with radioactive iodine uptake

(also ultrasound + doppler & see increased flow in thyroid)

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25
Q

treatments for hyperthyroidism

A

symptomatic treatment (oral/IV rehydration, beta-blockers)

antithyroid drugs (thioamids)

  • Methimazole
  • Propylthiouracil (1st trimester in pregnancy)

RADIOACTIVE IODINE TREATMENT

surgery

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26
Q

who are thioamides good for?

A

patients with mild hyperthyroidism/small goiters who are likely to go into remission or not candidates for surgery or waiting radioactive iodine treatment

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27
Q

side effects of thioamides?

A

agranulocytosis

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28
Q

what is the treatment of choice for hyperthyroidism?

A

Radioactive iodine treatment

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29
Q

how does radioactive iodine treatment work and what’s its downfall?

A

PO single dose

  • destroys thyroid over weeks
  • results in permanent hypothyroidism, requiring Levothyroxine for the rest of your life
30
Q

when is surgery for hyperthyroidism indicated & what will it require?

A

Indicated for non compliant patients, patients with very lager goiters compressing structures and children

Will required lifelong Levothyroxine

31
Q

what is thyroid storm?

A

very rare, bad extreme of hyperthyroidism

occurs in people with UNTREATED hyperthyroidism

brought on by a major life stress such as trauma, heart attack, or infection

32
Q

how do you diagnose thyroid storm?

A

clinical (can’t draw labs)

33
Q

how does thyroid storm present?

A
  • fever, tachycardia, HTN, neurological and GI abnormalities
  • HTN may be followed by CHF that is associated with hypotension and shock
  • Delirium, severe tachycardia, vomiting, diarrhea, dehydration, fever, heart failure, pulmonary edema
  • High mortality rate – invariably fatal if left untreated
34
Q

what are the main treatments for thyroid storm?

A

IV thiourea - prevents thyroid from producing anymore, but doesn’t effect T4/T3 that’s circulating

Iodine compound PO (Lugol’s solution) - given one hr after Thiourea; blocks release and conversion of T4/T3

35
Q

what is the most common cause of hypothyroidism in the US?

A

Hashimoto’s

36
Q

when does the risk of hypothyroidism increase?

A

increases with age (most prevalent in the elderly)

37
Q

where are goiters commonly seen & what does a +goiter correlate with?

A

Goiters are commonly seen in areas where iodine deficiency is common due to diet

+ goiter, correlation with progression to papillary thyroid cancer

38
Q

what is hypothyroidisms bad extreme?

A

Myxedema coma - has high mortality rate

39
Q

what is Hashimoto’s?

A 
Autoimmune Thyroiditis (Hashimoto's)
e.g. Chronic Lymphocytic Thyroiditis

-Body attacks the thyroid and destroys it

+Antibodies is hallmark

40
Q

what is the hallmark of Hashimoto’s?

A

+ antibodies

41
Q

other causes of hypothyroidism? (besides Hashimoto’s)

A

Thyroidectomy (for hyperthyroidism, goiter, thyroid cancer)

Central Hypothyroidism HPO axis deficiency

42
Q

what are the common symptoms of hypothyroidism?

A

EVERYTHING SLOWS DOWN (VS HYPERTHYROIDISM IS FAST)

  • fatigue, lethargy, depression
  • cold intolerance
  • weight gain
  • dry skin
  • thinning of hair
  • puffy face/eyelid
  • goiter (in both hyper/hypo)
  • bradycardia
  • delayed reflex
43
Q

what is the best screening test for Hashimoto’s?

A

TSH (will be elevated b/c not producing enough T4/T3, so increasing more TSH)

44
Q

what will T4/T3 levels be in Hashimoto’s?

A

low T4/T3

45
Q

what is the treatment of Hashimoto’s?

A

Levothyroxine - take with water in the morning after overnight fasting

Levo is T4, body convert it to T3

46
Q

why isn’t T3 given instead of Levo (T4)?

A

b/c T3 has short half-life

47
Q

how do you titrate Levo?

A

If elderly, start low and tirate up

Titrate dose up while taking certain medications that are hepatically metabolized

Titrate up as needed based on symptoms and labs (titrate every 6-8 weeks)

48
Q

what antibodies are used for diagnosis of Hashimoto’s?

A

antithyroid peroxidase TPO Ab & antithyroglobulin antibodies TgAb

WILL BE ELEVATED

49
Q

what is myxedema coma?

A
  • Severe, life-threatening hypothyroidism
  • Impaired cognition, confusion coma (myxedema coma)
  • Most often seen in elderly and those who have stopped taking meds
  • Severe hypothermia, hypoventilation (so become hypercarbic), hyponatremia, hypoglycemia, and hypotension
  • Rhabdomyolysis and acute kidney injury may occur (b/c pt not moving)
50
Q

treatment of myxedema coma?

A
  • Large doses of levothyroxine IV
  • Hypothermic warm only with blankets, since faster warming can precipitate cardiovascular collapse
  • Hypercapnia intubate and assist mechanical ventilation
  • Infections must e detected and treated aggressively
  • Suspected concomitant adrenal insufficiency hydrocortisone
51
Q

what is euthyroid sick syndrome? what are the labs like? txt?

A

abnormal thyroid hormone levels (TSH normal, T4 low/normal, T3 low) with normal thyroid gland fxn seen with non thyroidal illness (e.g., MI, DKA, CRF, cirrhosis)

  • serum cortisol elevated & antibodies negative
    txt: treat the underlying cause
52
Q

what is thyroiditis

A

Thyroiditis includes a group of individual disorders causing thyroidal inflammation but presenting in different ways (Hyperthyroid/Euthyroid/Hypothyroid)

53
Q

what are causes of thyroiditis?

A
  • Subacute Lymphocytic Thyroiditis/Silent Thyroiditis/Painless Thyroiditis (painless)
  • Post-Partum Thyroiditis (painless)
  • Subacute Granulomatous Thyroiditis (de Quervain’s) (painful)
  • Chronic Lymphocytic thyroiditis (Hashimoto’s Thyroiditis) (painless)
  • drug induced (painful)
54
Q

what is Subacute Lymphocytic Thyroiditis/Silent Thyroiditis/Painless Thyroiditis

A
  • Painless
  • Spontaneous or triggers often autoimmune mediated and can also occur after exposure to certain drugs, such as interferon-alpha, interleukin-2, LITHIUM and tyrosine kinase inhibitors
  • 50% will have antibodies

How to decipher from Graves?
-Little to no thyroid enlargement, no Graves ophthalmopathy

55
Q

what is Post-Partum Thyroiditis?

A
  • 2-12 months post partum
  • Painless
  • Usually transient
  • > 80% will have antibodies

Hyperthyroid will last a few weeks (before get to hypothyroid)
-Most will progress to hypothyroid state which may last few months

-Recurrence rate high 70%

56
Q

what is Subacute Granulomatous Thyroiditis (de Quervain’s)?

A
  • Lower grade fever
  • PAINFUL
  • Viral Etiology – h/x URI with extreme neck pain
  • Painful nodule, throat dysphagia
  • *overlooked because symptoms mimic pharyngitis

Must r/o infectious bacterial suppurative thyroiditis

57
Q

what is Chronic Lymphocytic thyroiditis?

A

(Hashimoto’s)

-NOT PAINFUL, HAVE LIFELONG HYPOTHYROID

58
Q

what is drug induced thyroiditis?

A

NOT PAINFUL

Caused by:

  • Amiodarone
  • Lithium
  • Phenytoin
  • Radioactive Iodine
59
Q

what is amiodarone thyroiditis?

A
  • Can occur 4 months – 3 years after starting
  • Clinically significant hypothyroidism occurs in about 15-20% patients
  • Type 1: active production of excessive hormones due to too much free iodine
  • Type 2: destructive thyroiditis which releases stored hormones

Typically resolves over several months s/p discontinuation of medication

60
Q

how do you treat thyroiditis?

A

TREAT SYMPTOMS

treat with LEvothyroxine if in hypothyroid state

DO NOT treat with Thionamides (if in hyperthyroid state)

61
Q

what is the most common malignancy of the endocrine system? & types?

A

Thyroid carcinoma
-death rate is low

Types: papillary, follicular, medullary, and anaplastic carcinoma

62
Q

risk factors for thyroid carcinoma?

A
  • History of radiation exposure
  • Multiple Endocrine Neoplasia (MEN)
  • Family history of thyroid cancer
  • ?Hashimoto’s disease
  • ?Iodine deficiency: follicular carcinoma
  • Nodule dx <30 y.o and >60 y.o
63
Q

signs & symptoms of thyroid cancer?

A

Painless, palpable nodule
(Firm non-mobile nodules suspicious for malignancy)

  • Rapid growth indicates ominous sign
  • Firm cervical masses highly suggestive of regional lymph node and metastasis

-Vocal cord paralysis, hoarse voice

64
Q

what is papillary thyroid cancer?

A
  • Most common thyroid cancer (70-90%)
  • Psammoma bodies – cleaved nuclei
  • Spread via lymphatics as well as hematogenously (bone, lungs)
  • Slow growth
  • Found early, excellent prognosis
65
Q

what is follicular thyroid cancer?

A
  • More common in iodine deficient regions*

- Tends to spread hematogenously (bone, lung, CNS)

66
Q

what is medullary thyroid cancer?

A

Associated with MEN2A and 2B

  • Most common cause of mortality in MEN patients
  • Some advocate for prophylactic thyroidectomy
  • Calcitonin will be elevated
  • Management is primarily surgical
67
Q

what is anaplastic thyroid cancer?

A
  • Poor differentiated (undifferentiated), aggressive, early metastasis to nodes and distant sites
  • Poor prognosis (survival 6 months)
  • Uncommon, inactivation of the p53 gene
68
Q

what is the diagnostic of choice for thyroid cancer?

A

FINE NEEDLE ASPIRATION
-usually done ultrasound guided

(ultrasound is not diagnostic of malignancy but will provide information for possible FNA)

69
Q

other diagnostics for thyroid cancer?

A

Labs:

  • TSH
  • serum calcitonin and CEA - medullary
  • PCR gremlin mutation - medullary

Thyroid Radioiodine imaging

  • Does not rule our carcinoma
  • Can provide hint whether malignant or not

CT or MRI w/out contrast

  • Just part of workup, not diagnostic
  • Evaluate soft tissue extension of large or suspicious thyroid mass
70
Q

thyroid cancer hot vs. cold

A

Terms used to describe findings on a radioactive iodine uptake scan

The hotter the nodule the less likely it is cancerous (cold nodule is concerning)

71
Q

what is thyroid cancer treatment?

A

THYROIDECTOMY – GOLD STANDARD!!!

Clin Med Exam 3 (6 decks)

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