Hypothyroidism

Question 1

what can be measured to investigate thyroid pathology

Answer 1

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

Question 2

what thyroid hormone and TSH levels are seen in primary hypothyroidism

Answer 2

free T3 and T4 are low, TSH is high

Question 3

what thyroid hormone and TSH levels are seen in secondary hypothyroidism

Answer 3

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

Question 4

what is hypothyroidism

Answer 4

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

Question 5

what is myxoedema

Answer 5

refers to severe hypothyroidism, a medical emergency

Question 6

in what groups of people is incidence of hypothyroidism higher

Answer 6

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

Question 7

what are the different types of causes for primary hypothyroidism

Answer 7

goitrous, non-goitrous or self-limiting

Question 8

give examples of goitrous causes of primary hypothyroidism

Answer 8

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

Question 9

give examples of non-goitrous causes of primary hypothyroidism

Answer 9

atrophic thyroiditis, post-ablative therapy

Question 10

give examples of self-limiting causes of primary hypothyroidism

Answer 10

withdrawal of antithyroid drugs, post-partum thyroiditis

Question 11

what is usually the cause of secondary hypothyroidism

Answer 11

diseases of the hypothalamus or pituitary gland

many of these!

Question 12

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

Answer 12

Hashimoto’s thyroiditis(autoimmune thyroiditis)

Question 13

describe what Hashimoto’s thyroiditis is

Answer 13

autoimmune destruction of the thyroid gland and reduced thyroid hormone production

Question 14

what is Hashimoto’s thyroiditis characterised by

Answer 14

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

Question 15

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

Answer 15

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

Question 16

what hair and skin clinical features are associated with hypothyroidism

Answer 16

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

Question 17

what thermogenesis and fluid retention clinical features are associated with hypothyroidism

Answer 17

cold intolerance and pitting oedema

Question 18

what cardiac clinical features are associated with hypothyroidism

Answer 18

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

Question 19

what metabolic clinical features are associated with hypothyroidism

Answer 19

hyperlipidaemia, decreased appetite, weight gain

Question 20

what GI clinical features are associated with hypothyroidism

Answer 20

constipation, megacolon, intestinal obstruction

Question 21

what respiratory clinical features are associated with hypothyroidism

Answer 21

deep hoarse voice, macroglossia, obstructive sleep apnoea

Question 22

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

Answer 22

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

Question 23

what gynae/reproductive clinical features are associated with hypothyroidism

Answer 23

menorrhagia, later oligo- or amenorrhea, hyperprolactinaemia

Question 24

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

Answer 24

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

Question 25

how quickly should normal metabolic rate be achieved in a hypothyroidism patient and why

Answer 25

restores gradually, as rapid restoration can precipitate cardiac arrhythmias

Question 26

what pharmacological therapy should be used for young patients with hypothyroidism

Answer 26

levothyroxine 50-100ug daily, adjusted every 4 weeks according to response

Question 27

what pharmacological therapy should be used for elderly patients with history of IHD

Answer 27

levothyroxine 25-50ug daily, adjusted every 4 weeks according to response

Question 28

how often should TSH of patients on treatment be tested

Answer 28

2 months after any dose change, but if patient is stabilised every 12-18 months

Question 29

what is the main treatment for hypothyroidism and when should it be taken

Answer 29

levothyroxine(T4), should be taken before breakfast

Question 30

how may dose requirement for levothyroxine change in pregnancy

Answer 30

can increase by 25-50%

Question 31

how is dose of levothyroxine on secondary hypothyroidism different to that of primary

Answer 31

TSH unreliable in secondary, titrate dose of levothyroxine to free T4 level

Question 32

in what patients is myxoedema coma typically seen in

Answer 32

elderly women with long standing unrecognised or untreated hypothyroidism
(mortality is 60%)

Question 33

what findings are seen in myxoedema coma

Answer 33

ECG = bradycardia, heart block, T inversion, QT prolongation
Type 2 resp failure = hypoxia. hypercarbia
10% have adrenal failure

Question 34

what treatment is used for myxoedema coma patients

Answer 34

intensive care, passively warm them, cardiac/fluid/U&E/BP/BG monitoring, broad antibiotics, thyroxine cautiously(hydrocortisone)