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Internal Medicine pt.1 > Thyroid > Flashcards

Thyroid Flashcards

1
Q

What are the physiological effects of thyroid hormones?

A
  • increase O2 consumption & glucose absorption
  • increase HR, excitability & conductivity
  • increase skeletal & sexual maturation
  • decreases serum cholesterol level
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2
Q

What affects total T3 & T4 measurements

A

Thyroxin binding globulin (TBG)

  • total T4 = 4 - 12
  • total T3 = 80 - 120

increase TBG -> pregnancy, estrogen, congenital
decrease TBG -> liver cell failure, nephrotic syndrome, malnutrition, congenital, androgens

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3
Q

Radio-active iodine uptake (RAIU) is useful in diagnosis of?

A

Hyperthyroidism
except in cases of -> thyrotoxicosis factitia
-> thyroiditis
-> ectopic thyroid tissue (struma ovarii)

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4
Q

What is the most sensitive test for differentiation between primary & secondary thyroid dysfunction?

A

Serum TSH

PRIMARY
hyperthyroidism -> increase T3 & T4 + decreased TSH
hypothyroidism -> decreased T3 & T4 + increased TSH

SECONDARY
hyperthyroidism -> increased T3 & T4 & TSH
hypothyroidism -> decreased T3 & T4 & TSH

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5
Q

What are the anti-thyroid antibodies that could be found?

A
  • Thyroid stimulating immunoglobulin (TSI or LATS) -> Graves’ disease
  • Anti-microsomal & antithyroglobulin -> Hashimoto’s thyroiditis
  • TSH binding inhibitory immunoglobulin (TBII) -> primary hypothyroidism
  • serum thyroglobulin -> increases in differentiated cancer thyroid
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6
Q

What is the significance of thyroid scanning using 99mTC?

A
  • defines areas of hot nodules or cold nodules
  • retrosternal goiter
  • ectopic thyroid tissue
  • functioning metastasis of thyroid carcinoma
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7
Q

What are the causes of thyrotoxicosis?

A

THYROID HYPERFUNCTION

  • Graves disease (Basedow disease)
  • toxic nodule
  • toxic adenoma
  • iodine induced hyperthyroidism
  • TSH-secreting pituitary tumor
  • choriocarcinoma

ABNORMAL THYROID HORMONE RELEASE

  • subacute thyroiditis
  • chronic thyroiditis with transient thyrotoxicosis (Hashitoxicosis)
  • Hamburger thyroiditis

EXTRA-THYROID TISSUE

  • Thyrotoxicosis factitia
  • ectopic thyroid tissue -> Struma ovarii or functioning metastatic follicular carcinoma
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8
Q

What is the cause of Grave’s disease?

A
  • auto-antibody belonging to IGg class -> TSI or LATS (thyroid stimulating immunoglobulin)
  • can lead to transient neonatal thyroiditis because antibodies can cross the placenta
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9
Q

What are the general manifestations of Grave’s disease?

A
  • progressive weight loss + increasing appetite -> hyperdefecation due to increase GIT motility
  • heat intolerance
  • increased sweating
  • nervousness, emotional liability
  • irritable, agitated
  • exaggerated reflexes
  • fine tremors
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10
Q

What are the cardiovascular manifestations of Graves disease?

A
  • all types of arrhythmias EXCEPT heart block
  • high cardiac output failure -> water-hammer pulse
  • flow murmur -> hyper dynamic circulation
  • increase systolic hypertension -> increase pulse pressure
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11
Q

What are the musculoskeletal manifestations of Grave’s disease?

A
  • Myopathy, Myasthenia Graves

- bone resorption -> hypercalcuria & hypercalcemia + osteoporosis

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12
Q

What are the skin manifestations of Graves disease?

A
  • warm with excessive sweating
  • onycholysis -> Plumer nail
  • orange peel thickening of pretibial area
  • clubbing of fingers & toes -> thyroid acropachy
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13
Q

What are the reproductive manifestations of Graves disease?

A
  • women -> oligomenorrhea & deceased fertility

- men -> impotence, decreased sperm count & gynecomastia

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14
Q

What are the ocular manifestations of Graves disease?

A

SPASTIC

  • Roenbach’s sign -> tremors of closed eyelids
  • Stellwag sign -> infrequent blinking
  • Dalrymple sign -> starring look
  • Von Graefe’s sign -> lid lag
  • Joffroy’s sign -> absence of forehead wrinkling

MECHANICAL (infiltrative opthalmopathy)

  • proptosis & ophthalmoplegia (diplopia)
  • Mobius sign -> lack of convergence
  • Conjunctivitis, chemosis, peri-orbital swelling
  • corneal ulceration, optic neuritis & optic atrophy
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15
Q

What are the causes of thyroid storm (thyrotoxicosis crises)?

A
  • excessive manipulation of thyroid during thyroidectomy
  • neglected severe hyperthyroidism + intercurrent illness

Clinical picture -> severeeee

  • tachycardia
  • fever
  • irritability
  • diarrhea
  • psychosis
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16
Q

What are the indications of medical treatment of hyperthyroidism?

A
  • thyrotoxicosis in pregnancy
  • cases complicated by Heart Failure
  • young patients < 25 yo
  • pre medication before surgery
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17
Q

What are the contra-indications of medical treatment of hyperthyroidism?

A
  • huge goiter
  • retrosternal goiter
  • suspicion of malignancy
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18
Q

What are the medications used in hyperthyroidism treatment?

A

THIONAMIDE -> inhibit thyroid peroxidase
- propyl thiouracil -> in pregnancy -> 300 - 600mg -> decrease peripheral production of T3 from T4
- methimazol -> 30 - 60mg
- carbimazol -> 30 - 60mg -> decreases the production of TSI
give for 6 weeks then follow up -> continue for 1 - 2 years

BETA BLOCKERS -> propranolol (inderal)

  • decreases excessive adrenergic activity
  • decreases converge of T4 to T3

Na Ipodate -> decreases T4 to T3 convergence
K. iodine -> decrease vascularity of gland
- used to prepare patient for surgery 10 days prior (5 drops)
Dexamethasone -> decreases secretion of thyroid hormone & T4

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19
Q

What are the side effects of thionamide drugs?

A
  • agranulocytosis
  • arthralgia
  • skin rash
  • serum sickness
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20
Q

What are the indications & contraindications of radiotherapy in hyperthyroidism?

A

Indications

  • recurrence after thyroidectomy
  • failure of medical treatment & unfit patient for surgery
  • patients refusing surgery

Contraindications

  • pregnancy, lactation, & childhood
  • huge & retrosternal goiter
21
Q

What should be the relationship between antithyroid drugs & radiotherapy?

A

antithyroid drugs should be stopped 10 days before radiotherapy & retaken 14 days after

  • so it does not interfere with the uptake of the radio-iodine
  • keep taking antithyroid drugs for a couple of months until the effect of the radiotherapy is apparent
22
Q

What are the side effects of radiotherapy in hyperthyroidism?

A
  • hypothyroidism
  • > if it occurs after 1 month: transient
  • > if it occurs after 1 year: permanent
  • thyroid carcinoma
  • fetal abnormalities & hypothyroidism in newborn if given during pregnancy
23
Q

What are the indications for surgical subtotal thyroidectomy?

A
  • allergy to antithyroid drugs
  • patient refusing radiotherapy
  • big & retrosternal goiters
  • multi nodular toxic goiter
  • malignant suspicion
24
Q

How should a patient be prepared for thyroidectomy?

A
  • thionamide drugs for several months before
  • inorganic iodine 7 - 10 days before surgery
  • beta blockers
25
Q

What are the complications of thyroidectomy?

A
  • hypothyroidism
  • hypoparathyroidism
  • recurrent hyperthyroidism
  • recurrent laryngeal nerve injury
26
Q

How should hyperthyroidism be treated in pregnancy?

A
  • propyl-thiouracil
  • surgical thyroidectomy if necessary ONLY in first or second trimester
  • special attention paid to newborn because it can develop hyperthyroidism due to TSI
27
Q

How is thyrotoxic crises treated?

A
  • ice bags, fluids & electrolytes
  • IV dexamethasone
  • IV propranolol
  • Ipodate (Na update)
  • antithyroid drugs in large doses -> propyl thiouracil 600mg then 300mg every 6 hours
  • antibiotics
  • K-iodide
28
Q

What are the non goitrous types of hypothyroidism?

A
  • congenital developmental defect
  • post surgery
  • post radiotherapy
  • idiopathic -> antibodies
29
Q

What are the goiterous types of hypothyroidism?

A
  • Pendred syndrome
  • endemic goiter -> iodine deficiency
  • maternally transmitted antithyroid drug or radiotherapy during pregnancy
  • drug induced
  • chronic thyroiditis EARLY in disease
30
Q

What are the neurological manifestations of myxoedema?

A
  • reduced memory, mental slowing, dementia -> myxedema madness, depression
  • delayed relaxation of tendon jerks -> suspended jerks
  • mucinous infiltration
  • > flexor retinaculum: carpal tunnel syndrome
  • > internal ear: progressive deafness
  • > vocal cords: hoarseness of voice
  • > tongue: slurred speech
31
Q

What are the cardiovascular manifestations of myxoedema?

A
  • sinus bradycardia -> heart block
  • cardiomyopathy -> heart failure
  • cholesterol pericarditis & pericardial effusion
  • atherosclerosis -> angina pectoris & intermittent claudication
  • hypertension -> increased peripheral resistance -> increased diastolic BP
  • hypotension only in myxedema coma
  • anemia
  • > normocytic -> bone marrow depression & decreased peripheral O2 requirements
  • > megaloblastic -> pernicious anemia (Vit B12)
  • microcytic hypochromic -> menorrhagia & achlorhydria
32
Q

What are the GIT manifestations of myxoedema?

A
  • dynamic ileus -> constipation, obstruction
  • achlorhydria -> pernicious anemia
  • ascites -> high cholesterol
33
Q

What are the musculoskeletal manifestations of myxoedema?

A
  • arthralgia
  • joint effusion
  • stiff muscles
34
Q

What are the skin & hair manifestations of myxoedema?

A
  • puffy face & coarse features
  • dry cold skin
  • orange due to accumulation of carotene
  • malar flush
  • sparse, brittle course hair
  • loss of outer 1/3rd of eyebrow
  • xanthelasma
35
Q

What are the reproductive manifestations of myxoedema?

A
  • menorrhagia
  • amenorrhea & galactorrhea (if associated with hyperprolactinaemia) -> increased in TRH
  • infertility
36
Q

What are the pulmonary & renal manifestations of myxoedema?

A

Pulmonary

  • pleural effusion
  • decreased ventilatory response to hypoxia & hypercapnia -> CO2 narcosis

Renal
- hyponatremia -> may be due to SIADH

37
Q

What are the metabolic & endocrinal manifestations of myxoedema?

A
  • growth & developmental retardation in children
  • weight gain & decreased appetite
  • hypothermia & cold intolerance
  • hyperlipidemia
38
Q

What are the causes of myxoedema coma?

A
  • long standing untreated hypothyroidism

- hypothyroidism with exposure to -> infection, cold, trauma, CNS depression

39
Q

What is the clinical picture of myxoedema coma?

A
  • subnormal temperature -> 34 - 35
  • external features of severe hypothyroidism & bradycardia
  • dilutional hyponatraemia
  • alveolar hypoventilation -> CO2 retention & narcosis
40
Q

What investigations are done for myxedema?

A
  • thyroid function
  • x-ray -> pericardial or pleural effusion
  • ECG -> low voltage, bradycardia
41
Q

How is myxoedema treated?

A

L thyroxin -> full effect in 2 - 3 months

- asses T3 & T4 & TSH in 6 weeks

42
Q

what are the indications for rapid correction of hypothyroidism?

A
  • neonatal, infantile, juvenile
  • myxedema coma
  • hypothyroid patient preparing for emergency surgery

-> IV administration of L-thyroxin + hydrocortisone

43
Q

What are the indications for slow correction of hypothyroidism?

A
  • elderly patients
  • patients with heart disease

-> start with 25 - 50ug/day -> increase 25-50ug every month -> until reaching 150 - 200ug

44
Q

How is myxedema coma managed?

A
  • hydrocortisone 100mg FIRST -> incase associated with adrenal insufficiency
  • IV L-thyroxin -> 500ug
  • assisted ventilation
  • avoid further heat loss
45
Q

What is the cause & clinical picture of subacute thyroiditis? (De Quarvain)

A
  • follows UPPER RESPIRATORY TRACT INFECTION
  • pain over thyroid or referred to lower jaw, ear, occiput
  • fever, nodular thyroid, dysphagia
46
Q

What will be found on investigation of subacute thyroiditis & how should it be treated?

A
  • increase T4 due to leakage in the beginning -> euthyroid -> hypothyroid -> recovery
  • decreased RAIU
  • increased ESR

treat using

  • aspirin -> in mild cases
  • prednisone 15-20mg & propranolol -> in severe cases
47
Q

What is chronic lymphocytic thyroiditis?

A

HASHIMOTO’S -> autoimmune chronic thyroid inflammation

  • increase T4 initially -> hypothyroidism later
  • high tire of antimicrosomal antibodies -> could lead to Hashitoxicosis

treat using levothyroxin

48
Q

What are the high risk factors for malignancy in a thyroid nodule?

A

HISTORY

  • head & neck irradiation
  • nuclear radiation exposure
  • rapid growth
  • recent onset
  • young age
  • male
  • familial (medullary then papillary)

PHYSICAL EXAM

  • hard nodule
  • fixed
  • lymphadenopathy
  • vocal cord paralysis
  • distant metastasis

LAB & IMAGING

  • elevated calcitonin
  • cold nodule on technetium
  • solid lesion with micro calcification on US

Internal Medicine pt.1 (33 decks)

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