Hypothyroidism Flashcards

1
Q

what can be measured to investigate thyroid pathology

A

TSH(reflects tissue thyroid hormone action), free T3 and free T4

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2
Q

what thyroid hormone and TSH levels are seen in primary hypothyroidism

A

free T3 and T4 are low, TSH is high

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3
Q

what thyroid hormone and TSH levels are seen in secondary hypothyroidism

A

free T3 and T4 are low, TSH is low/normal

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4
Q

what is hypothyroidism

A

any disorder that results in insufficient secretion of thyroid hormones from thyroid gland

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5
Q

what is myxoedema

A

refers to severe hypothyroidism, a medical emergency

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6
Q

in what groups of people is incidence of hypothyroidism higher

A

women 5-10 times more than men, >60 increased risk, white > hispanic/african-american, higher in areas of high iodine intake

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7
Q

what are the different types of causes for primary hypothyroidism

A

goitrous, non-goitrous or self-limiting

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8
Q

give examples of goitrous causes of primary hypothyroidism

A

chronic thyroiditis(Hashimoto’s), iodine deficiency, drug induced(eg amiodarone)

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9
Q

give examples of non-goitrous causes of primary hypothyroidism

A

atrophic thyroiditis, post-ablative therapy

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10
Q

give examples of self-limiting causes of primary hypothyroidism

A

withdrawal of antithyroid drugs, post-partum thyroiditis

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11
Q

what is usually the cause of secondary hypothyroidism

A

diseases of the hypothalamus or pituitary gland

many of these!

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12
Q

what is the most common cause of hypothyroidism in the western world

A

Hashimoto’s thyroiditis(autoimmune thyroiditis)

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13
Q

describe what Hashimoto’s thyroiditis is

A

autoimmune destruction of the thyroid gland and reduced thyroid hormone production

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14
Q

what is Hashimoto’s thyroiditis characterised by

A

antibodies against thyroid perxidase(TPO) and T cell infiltrate and inflammation under microscope

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15
Q

what gender is Hashimoto’ s thyroiditis seen in more commonly, and what is often in their FH

A

female > male, often FH of autoimmune thyroiditis or other autoimmune disease

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16
Q

what hair and skin clinical features are associated with hypothyroidism

A

coarse/sparse hair, periorbital puffiness, pale cool skin/feels doughy to touch, vitiligo may be present, dull/expressionless face

17
Q

what thermogenesis and fluid retention clinical features are associated with hypothyroidism

A

cold intolerance and pitting oedema

18
Q

what cardiac clinical features are associated with hypothyroidism

A

reduced HR, cardiac dilatation, pericardial effusion, worsening of HF

19
Q

what metabolic clinical features are associated with hypothyroidism

A

hyperlipidaemia, decreased appetite, weight gain

20
Q

what GI clinical features are associated with hypothyroidism

A

constipation, megacolon, intestinal obstruction

21
Q

what respiratory clinical features are associated with hypothyroidism

A

deep hoarse voice, macroglossia, obstructive sleep apnoea

22
Q

what are some of the neurological/CNS clinical features are associated with hypothyroidism

A

decreased intellectual/motor activities, depression, muscle stiffness, cramps, peripheral neuropathy, carpal tunnel syndrome

23
Q

what gynae/reproductive clinical features are associated with hypothyroidism

A

menorrhagia, later oligo- or amenorrhea, hyperprolactinaemia

24
Q

what thyroid autoantibodies are used in autoimmune hypothyroidism diagnosis, and how often are they seen

A

anti-TPO antibody(95%), anti-thyroglobulin antibody(60%), TSH receptor antibody(10-20%)

25
how quickly should normal metabolic rate be achieved in a hypothyroidism patient and why
restores gradually, as rapid restoration can precipitate cardiac arrhythmias
26
what pharmacological therapy should be used for young patients with hypothyroidism
levothyroxine 50-100ug daily, adjusted every 4 weeks according to response
27
what pharmacological therapy should be used for elderly patients with history of IHD
levothyroxine 25-50ug daily, adjusted every 4 weeks according to response
28
how often should TSH of patients on treatment be tested
2 months after any dose change, but if patient is stabilised every 12-18 months
29
what is the main treatment for hypothyroidism and when should it be taken
levothyroxine(T4), should be taken before breakfast
30
how may dose requirement for levothyroxine change in pregnancy
can increase by 25-50%
31
how is dose of levothyroxine on secondary hypothyroidism different to that of primary
TSH unreliable in secondary, titrate dose of levothyroxine to free T4 level
32
in what patients is myxoedema coma typically seen in
elderly women with long standing unrecognised or untreated hypothyroidism (mortality is 60%)
33
what findings are seen in myxoedema coma
ECG = bradycardia, heart block, T inversion, QT prolongation Type 2 resp failure = hypoxia. hypercarbia 10% have adrenal failure
34
what treatment is used for myxoedema coma patients
intensive care, passively warm them, cardiac/fluid/U&E/BP/BG monitoring, broad antibiotics, thyroxine cautiously(hydrocortisone)