3- hyperthyroidism & hypothyroidism Flashcards
fwhat is
a) primary thyroid problem
b) secondary thyroid problem
a) disease primarily affecting thyroid gland (can be goitrous or goitre)
b) not disease of thyroid itself, disease of hypothalamic or pituitary disease
what are the investigations for thyroid problems?
- blood tests
- thyroid stimulating hormone (TSH)
- free hormones (T3&T4)
what are findings for primary hypothyroidism?
- low T3&T4 (since thyroid not - making enough)
- also has high TSH (in response to low T3&4)
what is findings of primary hyperthyroidism?
- high T3 & T4 (since thyroid making too much likely through auto-antibodies)
- low TSH in response (to try and make less stimulation so less T3&4 produced)
what is findings of secondary hypothyroidism?
- T3 & T4 low (since hypo)
- this should mean that TSH is high since feedback mechanism but problem with pituitary or hypothalamus so TSH low or inappropriately normal
what are findings for secondary hyperthyroidism?
- T3 & T4 high (since hyper)
- should mean TSH low but since problem with hypothalamus or pituitary TSH high or inappropriately normal
what is common presentation of hypothyroidism?
= more in white female
- coarse, sparse hair
- dull expressionless face
- periorbital puffiness
- pale cool skin, doughy
- hypercarotenaemia
- pitting oedema
- cold intolerance
- maybe vitiligo
what are most common causes of primary hypothyroidism? (goitrous, non-goitrous)
goitrous
- hashimoto’s thyroiditis (autoimmune)
- iodine deficiency
- also drug induced (amiodarone)
non-goitrous
- atrophic thyroiditis (autoimmune)
- also post radiotherapy
what is subclinical hypothyroidism & hyperthyroidism?
hypothyroidism = where TSH high but T3 & T4 in normal ranges
hyperthyroidism = where TSH low but normal T3&T4
→they won’t have any clinical symptoms but could be at risk of developing hypothyroidism in future
- will only treat if subclinical hyperthyroidism with symptoms of osteoporosis or AF
when can you get self limiting primary hypothyroidism?
- first 6-12 months postpartum
- withdrawal of anti-thyroid drugs
what are causes of secondary hypothyroidism?
= problem in pituitary or hypothalamus (will cover more in pituitary lecture)
what is hashimoto’s thyroiditis?
autoimmune destruction of thyroid gland & reduced thyroid hormone production
what are steps to diagnosis of hashimoto’s thyroiditis?
- will find low T3&T4 and high TSH
- then check antibodies = thyroid perioxidase antibody (TPO). if positive defo hashimoto’s
what are some extra clinical features of hypothyroidism?
loads!! - basically down regulates everywhere
- cardiac = reduce HR, worse heart failure
- metabolic = hyperlipidaemia
- GI = constipation
- resp = deep, hoarse voice
- neurological = low mood, muscle stiffness
- reproductive = heavy periods
what is the most important thyroid antibody to test for hashimoto’s?
TPO = thyroid peroxidase
what is hypothyroidism management?
in young patients = 50-100 micrograms levothyroxine
in old patients = 25-50 micrograms levothyroxine (start low and adjust 4 weekly as don’t want to fluctuate cardiac rate since make arrhythmia)
how do you monitor amount of treatment to give for primary and secondary hypothyroidism?
monitor primary hypothyroidism with TSH - when normalises, you’re giving good levothyroxine
monitor secondary hypothyroidism by titrating dose to fT4 level
what is myxoedema coma? treatment?
presentation of severe hypothyroidism (high mortality)
- typically elderly women with longstanding unrecognised or untreated hypothyroidism
- will have low voltage and slow HR on ECG, type 2 resp failure (slow breathing)
treat = intensive care, cardiac monitor for arrhythmias, antibiotics (as often triggered by infection), hydrocortisone (helps kidney stuff)
what is thyrotoxicosis?
clinical manifestation of hyperthyroidism - when tissues exposed to excess thyroid
what are some signs & symptoms of hyperthyroidism?
loads again! basically everything sped up. increased metabolic rate with increase glucose release & uptake to maintain higher metabolism
- cardiac = palpitations, AF
- sympathetic symptoms = tremor, sweating
- CNS = anxiety, nervousness, irritability
- GI = frequent, loose bowel
- vision
- hair = brittle, thin hair, rapid fingernail growth
- reproductive = lighter menstruation
- muscles
- thermogenesis = intolerance to heat
what are main causes of primary hyperthyroidism?
excess thyroid stimulation:
- graves disease (autoimmune)
- thyroid cancer etc
thyroid nodules with autonomous function
- toxic multinodular goiter (especially elderly)
what are causes of secondary hyperthyroidism?
*thyroid making too many hormones but not thyroid fault
- post partum or drugs e.g. amiodarone causing thyroiditis (inflammation)
- overtreatment levothyroxine = giving too much exogenous thyroid hormones
- ectopic thyroid tissue making T3 &T4 e.g. metastatic thyroid carcinoma
what is graves disease?
= autoimmune condition causing primary hyperthyroidism
what is typical presentation of graves disease?
- more in younger people (smoking can increase risks so must stop!)
- has smooth large goitre
- pretibial myxoedema (big rashes on shins)
- thyroid acropachy (clubbing)
- graves eye disease
what are steps to diagnosis of graves disease?
- original labs will show high T3&T4 with low TSH
- next check TRAb antibodies (TSH receptor antibody) = if positive then defo graves
what is graves eye disease? management?
= they’re like very big eye bulge, you can also see white of eye like between eye lids
- occurs in 20% of graves patients and more risk in smoking
- can be unilateral or bilateral
management - choose between anti-thyroid drugs, radioiodine, surgery
what is nodular thyroid disease? management?
2nd most common cause of overactive thyroid
- more in older people
- can feel nodules on thyroid gland (graves goitre smooth)
management = doesn’t respond to anti-thyroid drugs so radioiodine or surgery
what are steps to diagnose nodular thyroid disease?
- increased T3&T4 with decreased TSH
- negative TRAb antibody (since not graves)
- scintigraphy = nuclear uptake scan
- thyroid ultrasound
what is thyroid storm?
= extreme hyperthyroidism - it’s a medical emergency
- often in hyperthyroid patients with acute infection or illness
what are treatment options for hyperthyroidism?
- antithyroid drugs - carbimazole (1st line) or propylthiouracil (PTU)
- radioiodine (contraindicated if graves eye disease)
- surgery - thyroidectomy (will then need levothyroxine replacement lifelong)
*can also give beta blockers, propranolol, to help symptoms
what are side effects of antithyroid drugs?
- generally well tolerated, could get allergic rash or liver stuff but important one is
agranulocytosis = rare but severe. need to safety net for fever or sore throat (will get blood test to show if problem with bone marrow)
what is non-thyroidal illness?
= sick euthyroid syndrome
- commonly encountered in people unwell in hospital
- basically illness can affect thyroid function. usually just get checked again once recovered from illness to confirm just sick thyroid and not genuine problem
- TSH usually suppressed but rises in recovery
