Hyperthyroidism and Hypothyroidism Flashcards
what is the difference between primary and secondary thyroid disease?
primary affects thyroid gland itself, secondary is usually from hypothalamus/pituitary gland in brain
can you get goitre in secondary thyroid disease?
no
another word for TSH?
thyrotropin
where is TSH released and by what?
by thyrotroph cells in the anterior pituitary gland
what provokes TSH to be released?
release of TRH (thyrotropin releasing hormone)
what is T4?
thyroxine
what is T3?
lyrothyronine
which percentage of thyroid hormone secreted is T4?
80%
name the plasma proteins that T3 and T4 bind to
TBG (thyroid binding globulin)
albumin
pre-albumin
where is TRH made?
hypothalamus
what does TSH do?
stimulates thyroid gland to make T3 and T4
what do T3 and 4 do?
switch off TSH production
what does the liver do to T3 and 4?
T4 is converted to T3
what happens to T3/4 and TSH levels in primary hypothyroidism?
free T3/4 = LOW
TSH = HIGH
what happens to T3/4 and TSH levels in primary hyperthyroidism?
free T3/4 = HIGH
TSH = LOW
what happens to T3/4 and TSH levels in secondary hypothyroidism?
T3/4wha = low TSH = low
what happens to T3/4 and TSH in secondary hyperthyroidism?
t3/4 = high tsh = high
what is hypothyroidism?
insufficient secretion of thyroid hormones from the thyroid gland
what is myxoedema?
severe hypothyroidism
what SHOULD happen to TSH when T3/4 is low?
it should increase
intake of what chemical is linked to hypothyroidism?
iodine
goitrous causes of primary hypothyroidism?
chronic thyroiditis
iodine deficiency
drug induced
maternally transmitted
what drugs can cause hypothyroidism?
amiodarone
lithium
non goitrous causes of hypothyroidism?
atrophic thyroiditis
post ablative or radiotherapy
congenital
what is thyroperoxidase?
an enzyme involved in thyroid hormone synthesis
most common cause of hypothyroid in western world?
autoimmune hypothyroid eg hashimoto’s thyroiditis
histological appearance of autoimmune hypothyroid?
t cell infiltrates
inflammation
main pathological process in autoimmune hypothyroid?
antibodies made against thyroperoxidase (TPO)
which thyroid related substance is the most highly produced in hypothyroidism?
TSH
clinical facial features of hypothyroidism?
thin hair dull, expressionless face periorbital puffiness pale, cool skin that is doughy vitiligo sometimes hypocarotenaemia patient is cold all the time
cardio clinical features of hypothyroidism?
bradycardia, cardiac dilatation, pericardial effusion, worse heart failure
GI features of hypothyroid?
constipation
metabolic features of hypothyroid?
weight gain
decreased appetite
hyperlipidaemia
why should you look at the legs in suspected hypothyroidism?
look for pitting oedema
respiratory features of hypothyroidism?
deep hoarse voice
macroglossia
obstructive sleep apnoea
neuro features of hypothyroid?
confusion depression psychosis muscle stiffness/pain peripheral neuropathy bad vision carpal tunnel
what effect can hypothyroid have on periods?
can make them longer, not happen at all
effect of hypothyroid on MCV?
increase
effect of hypothyroid on:
CK
LDL
increase
increase
what electrolyte is particularly lost in hypothyroid?
hyponatraemia
what autoantibody is particularly sensitive in autoimmune hypothyroid?
anti-TPO
what is the main autoantibody involved in graves disease?
TSH receptors
what can rapid restoration of metabolic rate cause?
cardiac arrhythmias
treatment for younger patients with hypothyroid?
levothyroxine at 50-100 ug daily
hypothyroid treatment for older patients with heart disease?
levothyroxine at 25-50 ug daily
what should you do when you change the dose of thyroxine given for hypothyroid?
check TSH 2 months after
why is TSH checked in hypothyroid?
can be used as a marker in PRIMARY only to see if treatment is working
when should T4 be taken?
before breakfast
is T4 or T3 more potent?
T3
what drugs interfere with action of thyroxine?
PPIs
iron tablets
how is dose of thyroxine changed in pregnant women with hypothyroid?
increase dose by 25-50%
who does myxoedema coma affect?
elderly women with untreated hypothyroidism
ECG findings of myxoedema coma?
varying heart block
T wave inversion
QT prolongation
clinical presentation of myxoedema coma?
type 2 resp failure adrenal failure bradycardia heart block low body temp
treatment for myxoedema coma?
rewarm
cardiac monitoring
broad spectrum antibiotics
thyroxine cautiously
how is thyrotoxicosis different from hyperthyroidism?
tissues are exposed to excess thyroid hormone, doesnt mean there is a problem with the thyroid gland itself
cardiac symptoms of thyrotoxicosis?
palpitations
AF
HF (Rare)
sympathetic nervous effects of thyrotoxicosis?
tremor
sweating
CNS effects of thyrotoxicosis?
anxiety
nervousness
irritability
sleep disturbance
GI effects of thyrotoxicosis?
frequent, loose bowel movements
vision effects of thyrotoxicosis?
lid retraction
double vision
proptosis
hair and nail symptoms of thyrotoxicosis?
thin hair
rapid nail growth
do you get weight loss or gain in thyrotoxicosis?
weight loss
are you intolerant to cold or heat in thyrotoxicosis?
heat
hyperthyroid causes of thyrotoxicosis?
excessive thyroid stimulation eg graves OR thyroid nodules with autonomous function
non hyperthyroid causes of thyrotoxicosis?
thyroiditis
exogenous thyroid hormones
ectopic thyroid tissue
what forms of thyroiditis can cause thyrotoxicosis?
subacute thyroiditis (viral) post partum thyroiditis
is graves disease more common in younger or older publications?
younger
most common cause of graves disease?
genetic factors plus environmental
what would TSH and T3/4 look like in graves disease?
TSH- LOW
T3/4 = HIGH
what does hypercalcaemia + increased ALP indicate?
increased bone turnover
what thyroid condition is linked to osteoporosis
graves
how low is the TSH levels in graves?
can be almost undetectable
what autoantibody should be checked in graves?
TSH receptor antibody
clinical signs on examination that suggest graves disease?
pretibial myxoedema
thyroid acropachy
thyroid bruit
graves eye disease
when is the only time you would hear a thyroid bruit
graves disease if there was a large goitre
lifestyle advice for graves disease?
STOP smoking, makes eyes worse
treatment for mild graves eye disease?
topical lubricant
treatment for severe graves eye disease?
steroids
radiotherapy
surgery
is onset of graves insidious and slow or acute and severe?
acute/severe
who gets nodular thyroid tdisease?
older patients
how an you differentiate nodular thyroid disease from graves?
slower onset
in older people
thyroid feels nodular but is smooth in graves
goitre can be asymmetrical
effect of nodular thyroid disease on T3/4 and TSH?
increases T3/4
decreases TSH
what result will nodular thyroid disease get when checking TSH receptor antibody
negative
tests for nodular thyroid disease?
TSH receptor antibody test
thyroid USS
thyroid hormone levels
is thyroid storm severe?
yes, do ABC
what is thyroid storm?
severe hyperthyroidism
clinical features of thyroid storm?
resp and cardio collapse
hyperthermia
exaggerated reflexes
most common cause of thyroid sorm?
hyperthyroid patients with an acute infection or recent thyroid surgery
treatment for thyroid storm?
ugol's iodine glucocorticoids beta blockers for tachycardia fluids propylthiouracil
1st line drug for hyperthyroidism?
carbimazole OD
1st line drug for 1st trimester of pregnancy in someone who is hyperthyroid?
propylthiouracil BD
treatment for graves disease?
dose titration of carbimazole
side effects of antithyroid drugs for hyperthyroidism?
allergy
jaundice
increased liver enzymes
agranulocytosis
what is agranulocytosis?
absence of neutrophils
what should you do if a patient on antithyroid drugs gets agranulocytosis?
take them off them; they cant be used again
when is the risk of agranulocytosis highest in hyperthyroid patients?
first 6 weeks of starting antithyroid drugs
what beta blocker is of particular use in hyperthyroidism and why?
propranolol, stops T3-T4 conversion in liver
1st line treatment for relapsed graves disease?
radioiodine
is radioiodine safe in pregnancy?
NO
why can’t radioiodine be used in active graves disease?
cause hypothyroid
what should you do in graves disease when radioiodine is contraindicated?
thyroidectomy
surgical risks of thyroidectomy?
recurrent laryngeal nerve palsy
hypothyroidism
hypoparathyroidism
clinical symptoms of subacute thyroiditis?
neck tenderness
fever
viral symptoms
common cause of subacute thyroiditis?
viral infection
what age group is most commonly affected by subacute thyroiditis?
20-50s
what do the TFTs look like in patients with inhibited DIO1 receptors?
increased T4
decreased T3
normal TSH
which type of thyroid disease occurs in iodine deficient areas?
hyperthyroidism
what do you call mild thyroid disease that could progress to hypo/hyperthyroidism?
subclinical thyroid disease