Thyroid Flashcards
What are the effects of TSH binding to the thyroid follicular cells?
GPCR, activates cAMP, activates:
- thyroglobulin synthesis
- iodide pumping
- thyroid peroxidase
- endocytosis, proteolysis, hormone release
What are the functional units of the thyroid gland?
thyroid follicle:
- follicular cells line the outside
- colloid filled with thyroglobulin
- parafollicular C cells between follicles for calcitonin secretion
What is the main cause of hypothyroidism in the UK?
- autoimmune disease
What are the symptoms of hypothyroidism?
- lethargy, weakness
- dry, scaly skin
- sensitive to cold weather
- depression
- hair loss
- memory loss
- weight gain
- constipation
- puffy face & gruff voice
What would be the results for diagnosis from TFTs?
- measure TSH and T4 levels
- raised TSH levels in response to low hormone production
TSH above 10mL - treat lifelong with T4
TSH 5 - 10mL - if symptomatic, treat with T4
What is the treatment for hypothyroidism?
lifelong T4, levothyroxine
- adults under 50: start with 50 - 100mcg
- adults over 50: start with 25mcg
titrate every 4 weeks
measure TSH 8 - 12 weeks and every three months initially then monitor every year for adult
monitor for angina - heart disease, T4 will increase heart rate
What are the patient counselling points for levothyroxine?
- life long treatment
- single daily dose
- don’t take calcium/iron/caffeine at the same time as it affects absorption
- careful when titrating doses
- medical exemptions
What is the most common cause of hyperthyroidism?
autoimmune disease, antibodies stimulate the TSH receptor on the thyroid gland
What are the symptoms of hyperthyroidism?
- anxious
- palpitations
- tremor
- weight loss
- tachycarida
- goitre
- heat intolerance
- warm skin
- difficulty sleeping
- diarrhoea
What would the TFTs show for someone with hyperthyroidism?
- TSH is LOW as there is more than enough T4/T3 being produced
What are the treatment options for hyperthyroidism?
- carbimazole
- propylthiouracil
What are the doses for carbimazole for hyperthyroidism?
- first choice drug
- 15 - 40mg daily
- till TFTs normal
- maintenance 12-18months
- then reduce
- longer term may be needed in relapses
What is the blocking-replacement regimen?
- completely block thyroid function and then replace the levothyroxine
- 40 - 60mg per day for 4 weeks
- then add thyroxine
- treat for up to 18 months
- function returns to normal
What drug is not recommended in pregnancy?
carbimazole
- increased risk of congenital malformations
What are the doses for propylthiouracil?
- 200mg- 400mg divided doses
- reduce to 50mg TDS maintenance
- use in pregnancy/those who cannot tolerate carbimazole
