Hyperthyroidism Flashcards

1
Q

definition

A

hyperthyroidism refers specifically to conditions in which overactivity of the thyroid gland and excess thyroid hormones leads to thyrotoxicosis

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2
Q

thyrotoxicosis definition

A

thyrotoxicosis is the clinical, physiological and biochemical state arising when tissues are exposed to excess thyroid hormone

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3
Q

hyperthyroidism and thyrotoxicosis are

A

not the same thing

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4
Q

symptoms of thyrotoxicosis

A
  • palpitations
  • atrial fibrillation
  • tremor
  • sweating
  • anxiety, nervousness, irritability, sleep disturbances
  • lid retraction
  • double vision (diplopia)
  • proptosis/ exophthalmus ( specific to graves disease)
  • muscle weakness especially in the thighs and upper arms ]
  • weight loss despite increased appetite
  • heat intolerance
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5
Q

causes of thyrotoxicosis associated with hyperthyroidism subtypes

A

excessive thyroid stimulation and thyroid nodules with autonomous function

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6
Q

causes of thyrotoxicosis which cause excessive stimulation of the thyroid gland

A
  • graves disease (most common)
  • hashitoxicosis
  • thyroid cancer (rare cause)
  • choriocarcinoma (type of gestational trophoblastic disease which secreted HCG i.e. trophoblast producing cancer occurring during pregnancy)
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7
Q

causes of thyrotoxicosis which cause a thyroid nodule with autonomous function

A
  • toxin solitaire nodule
  • toxic multi-nodular goitre
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8
Q

causes of thyrotoxicosis not associated with hyperthyroidism subtypes

A

thyroid inflammation, exogenous thyroid hormone, ectopic thyroid tissue

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9
Q

causes of thyrotoxicosis caused by thyroid inflammation

A
  • subacute (de quervains) thyroiditis
  • post- partum thyroiditis
  • drug induced thyroiditis ( amiodarone)
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10
Q

causes of thyrotoxicosis caused by exogenous thyroid hormones

A
  • overtretment of hypothyroidism with levothyroxine
  • thyrotoxicosis factitia (self induced thyrotoxicosis)
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11
Q

causes of thyrotoxicosis caused by ectopic thyroid tissue

A
  • metastatic thyroid carcinoma
  • struma ovarii (teratoma containing thyroid tissue)
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12
Q

graves disease is the

A

number one cause of hyperthyroidism

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13
Q

who is graves disease more common in

A

8x more common in woman with the average age of onset around 20-40 years old

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14
Q

whats is graves disease

A

autoimmune hyperthyroidism targeting the TSH receptor

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15
Q

symptoms of graves disease

A
  • all the symptoms of thyrotoxicosis and specific graves symptoms:
  • graves opthalmopathy
  • pretibial myxoedema
  • thyroid acropathy
  • thyroid bruit
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16
Q

graves opthalmopathy

A

occurs in 20% of patients with graves disease and is strongly associated with smoking
- exophthalmus (proptosis): abnormal anterior protrusion of the eyeball
- lid retraction

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17
Q

thyroid bruit

A

occurs only in graves disease and only if there is an extremely large goitre

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18
Q

laboratory investigations for hyperthyroidism

A

HIGH T3/T3 LOW TSH
- hypercalcaemia and increased ALP due to T3 activating osteoclasts causing increased bone turnover (graves disease is associated with osteoporosis)
- leucopenia (reduced white cell count)

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19
Q

autoantibodies

A
  • TSH receptor autoantibody (most specific to graves)
  • thyroglobulin antibody
  • thyroid peroxidase antibody ( anti-TPO)
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20
Q

if TSH receptor antibody is negative then

A

a radioactive iodine uptake test is required, if the antibody is positive then no scan is required, should show confluent increased uptake in graves disease

21
Q

first line management of graves disease

A

propranolol+ carbimazole

22
Q

why is propranolol used in graves disease

A

used for symptomatic relief of thyrotoxicosis symptoms but does not treat the underling disease

23
Q

propranolol is a

A

non-selective beta blockers which blocks beta 1 and beta 2 adrenoreceptors, it thyrotoxicosis is used because the blockage of beta-1- adrenoreceptors in the heart reduces heart rate, contractility and speed of conduction through the AV node and inhibits D101

24
Q

who is propranolol used with caution

A

asthmatics because it can cause bronchospasm as it blocks beta-2-adrenoreceptors causing bronchoconstriction

25
if propranolol cannot be used what is used
diltiazem which is a calcium channel blocker
26
when would carbimazole be contra-indicated and what is used instead
during the first trimester of pregnancy as there is a risk of aplastic cutis (absence of areas of skin) so PTU (propiothiouracil) is used instead
27
mechanism of action of carbimazole and propiothiouracil
after absorption is converted to the active form called methimazole which prevents thyroid peroxidase enzyme (TPO) from iodinating the tyrosine residues on thyroglobulin inhibiting the production of thyroid hormones (T3 AND T4)
28
rare side effect of propriothiouracil (PTU)
liver failure
29
theres 2 ways graves can be treated wit anti-thyroid drugs
1. dose titration over 12-18 months by starting with a low dose and titrating up 2. block and replace (over 6 months) start with a very high dose and induce hypothyroidism over 6 moths and then treat with levothyroxine
30
side effects of carbimazole and PTU
- 1-5% of people develop an allergic type reaction: rash, urticaria and arthralgia - cholestatic jaundice, increased liver enzyme and fulminant hepatic failure - agranulocytosis in 0.1-0.5%
31
what is agranulocytosis
disorder of bone marrow causing a severe reduction in the number of granulocytes causing a particularly severe neutropenia causing severe bacterial or fungal infections
32
when is the risk of agranulocytosis highest
in the first 6 months of starting mediation, patient should e warned verbally AND in writing to stop medications and have urgent FBCS if they have a fever, oral ulcer of oropharyngeal infection
33
medical management of graves disease has a
50% realisation rate
34
1st line management of graves disease after medical management
radioactive iodine ablation
35
radioactive iodine ablation is contradicted in
pregnant woman and after treatment woman should not conceive for at least a year should not be used in graves eye disease as it will worse it (but can be used in milder eye disease if it is first treated with steroids)
36
radioactive iodine ablation commonly causes what after treatment
hypothyroidism which will then need to be treated with levothyroxine
37
what is used if radioactive iodine is contraindicated
thyroidectomy
38
thyroidectomy can
damage the recurrent laryngeal nerve, cause hypoparathyroidism and hypothyroidism
39
thyroid storm
life threatening form of thyrotoxicosis which mostly occurs in people with untested graves disease when they get an acute infection/illness
40
laboratory investigations for thyroid storm
T3 AND T4 LEVELS VERY HIGH, TSH IS LOW
41
presentation of thyroid storm
- sweating - hypertension initially and in late stages causes hypotension - hyperthermia - exaggerated reflexes - altered mental status (delirium, seizures and coma)
42
management of thyroid storm
ABCDE IV PTU LUGOLS IODINE (works by saturating the thyroid gland) propranolol iv fluids hydrocortisone
43
toxic nodular thyroid disease caused by
- toxic nodular adenoma - toxic multi-nodular growth
44
what is felt on palpation in someone with toxic nodular thyroid disease
nodules felt rather than a goitre
45
occurs most often in
older patients
46
investigations for toxic nodular disease
- high T3 AND T4 and low TSH - antibody negative (TRAb) - high uptake in radioactive iodine uptake scan
47
what happens if TSH is normal or the radioactive iodine scan does not show increased uptake
the hyperthyroidism could be caused by thyroid cancer
48
management of toxic nodular thyroid disease
1st line= radioactive iodine ablation 2nd line= thyroidectomy
49
why is smoking cessation important
because smoking is the main risk factor for thyroid eye disease