Hypothyroidism

Question 1

Where does primary hypothyroidism arise from?

Answer 1

Thyroid gland itself

Question 2

What are the three classifications of primary hypothyroidism?

Answer 2

Goiterous
Non-goiterous
Self limiting

Question 3

What can cause a goiterous primary hypothyroidism?

Answer 3

Hashimoto’s thyroiditis
Iodine deficiency
Maternally transmitted anti thyroid agent
Drug induced

Question 4

What is Hashitmoto’s thyroiditis?

Answer 4

Autoimmune disease
destruction of thyroid gland
chronic inflammation

Question 5

What is the etiology of Hashimoto’s?

Answer 5

F>M

FHx AID

Question 6

What auto antibodies are involved in Hashimoto’s?

Answer 6

Anti TPA (thyroid peroxidase antibodies)

Question 7

What can be seen on miscroscopy of Hashimoto’s?

Answer 7

T cells and inflammation

Question 8

What drugs can cause a goiterous primary hypothyroidism?

Answer 8

Amiodarone
Lithium
IL-2
IFN alpha

Question 9

What are the causes of a non goiterous primary hypothyroidism?

Answer 9

Post radiation
Atrophic thyroiditis
Post ablative/surgey
Congenital

Question 10

What are the self limiting causes of primary hypothyroidism?

Answer 10

Withdrawal of thyroid suppressive therapy
Post partum thyroiditis
Subacute/chronic with transient hypothyroid

Question 11

Where are the sites of secondary hypothyroidism?

Answer 11

Hypothalamus

Pituitary

Question 12

What hypothalamic causes of secondary hypothyroidism are there?

Answer 12

infection eg encephalitis
infiltration eg sarcoidosis
neoplasm eg craniopharyngioma
congenital

Question 13

What pituitary causes of secondary hypothyroidism are there?

Answer 13

panhypopituitarism
TSH deficiency
infection
infiltration
neoplasm 
trauma

Question 14

What laboratory tests can be used to show hypothyroidism?

Answer 14

Raised TSH
Low fT4
Low fT3
Raised CK
Raised LDL
Reduced Na+ (less renal tubule water loss)

Question 15

What test needs to be done to rule out B12 deficiency?

Answer 15

Test for macrolytes

Question 16

What are the hormone levels in

a) primary overt hypothyroidism?
b) primary subclinical hypothyroidism?
c) secondary hypothyroidism?

Answer 16

a) Raised TSH, Low fT4, Low fT3
b) Raised TSH, normal fT4, normal fT3
c) Low/normal TSH, low fT4, normal/low fT3

Question 17

What are the hair and skin changes in hypothyroidism?

Answer 17

Dry skin
Periorbital puffiness
Pale, cold, doughy skin
Coarse, sparse hair
Pitting oedema (fluid retention)

Question 18

What are the thermogenesis changes in hypothyroidism?

Answer 18

Cold intolerance

Question 19

What are the cardiac changes in hypothyroidism?

Answer 19

Bradycardia
Cardiac dilatation
worsening heart failure
pericardial effusion

Question 20

What are the gynaecological changes in hypothyroidism?

Answer 20

Menorraghia (heavy periods)

may lead to oligio or amenorrhoea

Question 21

What are the changes to the metabolic rate in hypothyroidism?

Answer 21

Increased appetite
Weight gain
hyperlipidaemia

Question 22

What are the GI changes in hypothyroidism?

Answer 22

constipation
megacolon
obsruction
ascites

Question 23

What are the repiratory changes in hypothyroidism?

Answer 23

deep hoarse voice

obstructive sleep apnoea

Question 24

What antibodies are found in autoimmune hypothyroidism?

Answer 24

Anti TPO (90%)
Anti TSH receptor (10-20%) blocking effect
Anti Thyroglobulin (60%)

Question 25

How can you treat hypothyroidism?

Answer 25

Thyroxine 50-100 ug in young 25-50 ug in elderly Take before breakfast (food often changes pH)

Question 26

How does treatment for hypothyroidism need monitored?

Answer 26

adjust every 4 weeks according to response check TSH levels every 2 months after a dose change once stable check TSH every 12 months

Question 27

How does rapid restoration of metabolic rate affect patient?

Answer 27

May percipatate arrythmias

Question 28

What changes to thyroxine dose need to be considered in pregnancy?

Answer 28

May need to increase dose

Question 29

What is myxoedema in the context of hypothyroidism?

Answer 29

Very severe hypothyroidism | Can lead to myxoedema coma

Question 30

What are the signs of myxoedema in a) adult | b) baby/child

Answer 30

a) puffy face, hands, feet | b) cretinism: dwarf, limited mental functioning

Question 31

What is the etiology of a myxoedema coma?

Answer 31

Elderly women | undiagnosed/untreated hypothyroidism

Question 32

What are the ECG findings in a myxoedema coma?

Answer 32

Bradycardia pronlonged QT Low voltage complexes Maybe heart block

Question 33

What are the respiratory effects in a myxoedema coma?

Answer 33

Thype 2 repiratory failure hypercabia hypoxia respiratory acidosis

Question 34

What happens to the adrenals in myxoedema coma?

Answer 34

co existing failure of adrenals

Question 35

What is the treatment for a myxoedema coma?

Answer 35

``` intensive care ABCDE passively rewarm monitor: ECG, BP, urine output, Sp02 Fluids, electrolytes Broad spectrum antibiotics ```

Question 36

Why does special care have to be taken when perscribing amiodarone?

Answer 36

causes thyrotoxicosis in low iodine areas | hypothyroidism in iodine overdose

Question 37

How is management of hyothyroidism changed in pregancy?

Answer 37

increase thyroxine my 25mcg as soon as pregnancy suspected check TFTs monthly for 20weeks then 2 monthly until term average dose increase is by 50% aim for TSH

Question 38

What are the risks of untreated hypothyroidism in pregnancy?

Answer 38

``` abortion preeclampsia abruption postpartum hge preterm labour ```

Question 39

How does gestational hCG associated thyrotoxicosis happen?

Answer 39

hyperemesis gravidarum(high hCG, low TSH) resolves in 20wks (only treat if persists past this)