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Endo Repro Exam > Thyroid Clinical > Flashcards

Thyroid Clinical Flashcards

1
Q

hyperthyroidism - defined

A

*too much thyroid hormone
*elevated T3 and T4
*low TSH

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2
Q

hyperthyroidism - symptoms

A
  1. metabolism: heat intolerance, diaphoresis, weight loss, restlessness, hyperactivity, anxiety
  2. CV/resp: tachycardia, palpitations, arrhythmias, chest pain
  3. derm: warm, moist skin, onycholysis
  4. GI: diarrhea
  5. MSK: muscle weakness, hand tremors, osteoporosis
  6. neuropsych: anxiety, insomnia, psychosis, pressured speech
  7. repro: oligomenorrhea, amenorrhea, decreased libido, decreased fertility
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3
Q

causes of hyperthyroidism

A
  1. Graves’ Disease (most common cause)
  2. other causes include:
    -hyperfunctioning “toxic” adenoma (Plummer’s disease)
    -multinodular goiter
    -thyroiditis
    -hCG-related [pregnancy, cancer]
    -Jod-Basedow phenomenon
    -factitious/iatrogenic use of thyroid hormone
    -TSH secreting adenoma
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4
Q

Graves’ disease - overview

A

*an autoimmune cause of hyperthyroidism; most common cause of hyperthyroidism
*hallmark: + thyroid stimulating immunoglobulins (TSI) or TSH receptor antibodies (TRAb); autoantibodies bind the TSH receptor and stimulate hormone synthesis

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5
Q

Graves’ disease - exophthalmos

A

*exophthalmos (bulging eyes) - only occurs in Graves’ disease
*pathogenesis: TSI activates T cells → lymphocytic infiltration of the retroorbital space which increases inflammatory cytokines → orbital fibroblasts secrete GAGs to increase osmotic muscle swelling/inflammation and adipocyte build up → exophthalmos
*note - exophthalmos associated with HLA-DR3 and HLA-B8

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6
Q

Graves’ disease - clinical features

A

*exophthalmos
*periorbital edema
*lid lag (upper eyelid is high in downward gaze; increased sympathetic stimulation of superior tarsal muscle)
*smooth goiter
*pretibial myxedema (TSI stimulate pretibial dermal fibroblasts → skin thickening)
*Pemberton sign (goiter obstructs jugular venous flow as the thyroid is forced downward with raised arms)

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7
Q

Graves’ disease diagnosis - ultrasound

A

*US shows significantly increased blood flow to the thyroid

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8
Q

nuclear uptake & scan (Tc-99 pertechnetate thyroid scintigraphy) - overview

A

*give pt pertechnetate, which looks a lot like iodine (but isn’t used to make thyroid hormone)
*gets taken up into the thyroid cells
*uptake = gives us a % of how much pertechnetate is taken up
*scan = gives us a picture of where the pertechnetate is taken up

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9
Q

Graves’ disease diagnosis: nuclear uptake & scan (Tc-99 pertechnetate thyroid scintigraphy)

A

*scan reveals pattern of uptake similar to that of a normal thyroid, but much higher % of uptake in Graves’ disease
*homogenous distribution of uptake throughout the thyroid

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10
Q

Graves’ disease - treatment

A
  1. medications: inhibit thyroid peroxidase enzyme → blocks thyroid peroxidase → less tyrosine iodination and coupling → prevents formation of T3/T4
    -options for meds: methimazole, propylthiouracil (PTU)
    -ADEs: hepatic failure, agranulocytosis
  2. beta blockers (decrease hyperadrenergic sx) = INITIAL therapy to control symptoms
  3. other: thyroidectomy, radioactive iodine ablation
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11
Q

methimazole - MOA, ADEs

A

*MOA: inhibit thyroid peroxidase enzyme → less tyrosine iodination and coupling → prevents formation of T3/T4
*ADEs:
-hepatic failure (jaundice, abdominal pain, elevated LFTs)
-agranulocytosis (low absolute neutrophil count, fever, sore throat)
-teratogenic (avoid in pregnancy)

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12
Q

toxic adenoma / toxic multinodular goiter - nuclear uptake & scan (Tc-99 pertechnetate thyroid scintigraphy)

A

*nodular locations of uptake on scan
*focal patches of follicular cells become hyperfunctioning → hypersecretion of T3/T4 independent of TSH

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13
Q

thyroiditis - overview

A

*inflammation (damage) to the thyroid gland causes premade/stored thyroid hormone to leak into the bloodstream

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14
Q

subacute granulomatosis thyroiditis - overview

A

*aka de Quervain thyroiditis
*usually preceded by infection
*PAINFUL inflammation of the thyroid
*lab trends: hyperthyroid state → euthyroid → hypothyroid state → euthyroid
*typically self-resolves in several weeks

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15
Q

postpartum thyroiditis

A

*a mild, self-limiting variant to Hashimoto thyroiditis < 1 year after delivery

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16
Q

Riedel thyroiditis

A

*aka invasive fibrous thyroiditis
*can be due to IgG4 → progressive fibrosis of the thyroid gland and surrounding structures
*slowly enlarging, hard, fixed, non-tender thyroid gland
*may lead to hypothyroidism
*treatment = surgery; monitor parathyroid function

17
Q

thyroiditis - treatment

A

*mostly transient process, so does not require methimazole or PTU
*beta blocker may be used to help with symptoms until thyroiditis resolves
*NSAIDs for pain if needed

18
Q

hCG-mediated hyperthyroidism - overview

A

*TSH, hCG, LH, and FSH all share the same alpha subunit, but have different beta subunits
*at high levels, hCG can bind to TSH receptors
*human chorionic gonadotropin (hCG) is made almost exclusively by the placenta but also by some neoplasms; therefore, seen in pregnancy, molar pregnancy, choriocarcinoma
*transient, no treatment needed

19
Q

Jod-Basedow phenomenon - overview

A

*iodine-induced hyperthyroidism
*occurs when a pt with an underlying thyroid disorder is given excess iodine → excess hormone production by an abnormal thyroid gland that doesn’t respond to normal regulation
*pertinent history: excess source of iodine, such as administration of IV contrast, amiodarone, iodine supplements

20
Q

other causes of hyperthyroidism

A
  1. iatrogenic use of thyroid hormone
  2. TSH secreting adenoma (very rare, sx of pituitary mass with hyperthyroidism, tx = surgery)
  3. struma ovarii (thyroid hormone-secreting ovarian teratoma: hyperthyroidism + pelvic mass)
21
Q

thyroid storm - overview

A

*rare but life-threatening complication of hyperthyroidism (untreated or incompletely treated hyperthyroidism + acute stressor such as infection, trauma, surgery)
*presentation: agitation, delirium, fever, coma, tachyarrhythmias
*treatment:
-beta blocker
-PTU or methimazole
-glucocorticoids
-iodine

22
Q

hypothyroidism - defined

A

*too little thyroid hormone
*low T4 and T3
*elevated TSH

23
Q

hypothyroidism - symptoms

A
  1. metabolism: cold intolerance, weight gain, hyponatremia, hyperlipidemia
  2. CV/pulm: bradycardia, dyspnea on exertion
  3. derm: dry, cool skin, coarse brittle hair, alopecia
  4. GI: constipatiion
  5. MSK: proximal muscle weakness, carpal tunnel, myoedema
  6. neuropsych: fatigue/lethargy, depression, hyporeflexia
  7. repro: abnormal uterine bleeding, decreased libido, infertility
24
Q

hypothyroidism - features

A

*periorbital edema
*edema, tongue swelling
*goiter
*Queen Anne’s sign (thinning of distal 1/3 of the eyebrow)

25
Q

causes of hypothyroidism

A

*Hashimoto thyroiditis (most common)
*congenital hypothyroidism
*central hypothyroidism
*iodine deficiency
*medication-induced
*surgery/radiation

26
Q

Hashimoto thyroiditis - overview

A

*most common cause of hypothyroidism in iodine-sufficient countries
*an autoimmune cause of hypothyroidism

27
Q

Hashimoto thyroiditis - pathogenesis

A

*thyroid peroxidase (TPO) antibodies destroy follicular cells → decreased thyroid hormone production
*initial normal/high thyroid hormone levels followed by permanent hypothyroidism

28
Q

Hashimoto thyroiditis - risk factors

A

*female
*PMH/FHx of autoimmune disease
*Down Syndrome, Turner Syndrome
*HLA-DR5 haplotype

29
Q

congenital hypothyroidism - overview

A

*most common cause worldwide = iodine deficiency
*most common cause in USA = thyroid dysgenesis/agenesis
*thyroid hormone affects axon proliferation, dendrite branching, synaptogenesis, myelination, cell migration, growth, skeletal development
*undiagnosed/untreated congenital hypothyroidism → irreversible intellectual disability
-this is an emergency; newborn screening programs essential

30
Q

central hypothyroidism - overview

A

*thyroid gland is normal but signal from pituitary/hypothalamus is absent, so thyroid hormone isn’t produced
*labs = low TSH and low T4
*less common than primary hypothyroidism
*look for hx of pituitary disorders

31
Q

other causes of hypothyroidism

A
  1. iodine deficiency: no iodine → no organification → no T3/T4 production
  2. medication induced: amiodarone, lithium inhibits thyroid hormone synthesis + release
  3. surgery/radiation
32
Q

hypothyroidism - treatment

A

*goal = replace thyroid hormone
1. levothyroxine = T4 (Synthroid is the brand name)
2 liothyronine = T3; can add to levothyroxine regimen, but not prescribed alone

33
Q

myxedema coma - overview

A

*severe, potentially fatal complication of hypothyroidism
*hypothyroid state + stressor (infection, MI, stroke, surgery)
*severe hypothyroidism → decreased mental status, hypothermia, hypoglycemia, hyponatremia, hypoventilation, bradycardia, puffy hands/face
*elderly pts with hypothyroidism have highest risk

34
Q

amiodarone & thyroid

A

*amiodarone: anti-arrhythmic drug rich in iodine; can do anything to the thyroid:
-hypothyroidism: decreased conversion of T4 to T3
-hyperthyroidism: trigger autoimmune hyperthyroidism
-thyroiditis: can cause destruction of thyroid gland

Endo Repro Exam (56 decks)

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