Endo - Thyroid Disorders Flashcards
(31 cards)
What level of TSH is found in a patient with hypothyroidism + the thyroid gland has been destroyed by immune system?
high TSH
What is Graves’ disease?
→ autoimmune
→ antibodies bind to + stimulate TSH receptor
→ cause goitre (smooth) + hyperthyroidism
What are signs of Graves’ disease?
→ being warm + sweaty (heat intolerance) → tachycardia → exophthalmus → smooth enlarged goitre → increased bowel activity → weight loss despite increased appetite → oligomenorrhea / amenorrhea → pretibial myxedema → lid lag + other sympathetic features → breathlessness
What causes exophthalmus?
antibodies bind to muscles behind the eye causing bulge
What’s pretibial myxoedema?
other antibodies causes hypertrophy + swelling + growth of soft tissue at shins
What is myxedema?
severely advanced hypothyroidism
What does the thyroid gland look like in Graves’ Disease?
→ diffused enlargement + engorgement of smooth goitre
→ diffused goitre of large size after radioiodine uptake + sometimes in pyramidal lobe
What are the symptoms of Plummer’s Disease?
→ Toxic nodular goitre → NOT autoimmune → Benign adenoma that is overactive at making thyroxine. → NO pretibial myxoedema → NO exophthalmos
What does the thyroid gland look like in Plummer’s Disease?
→ only nodule is swollen due to hyperplasia
→ one-sided swelling on goitre, not very smooth, even after radioiodide uptake
What are the effects of thyroxine on the SNS?
→ sensitises beta adrenoreceptors to ambient levels of adrenaline + noradrenaline
→ causes apparent sympathetic activation
→ tachycardia, palpitations, tremor in hands, lid lag
What is a thyroid storm?
→ untreated hyperthyroidism
→ medical emergency
→ 50% mortality rate
What are the symptoms of a thyroid storm?
→ Hyperpyrexia > 41oC → accelerated tachycardia / arrhythmia → cardiac failure → delirium / frank psychosis → hepatocellular dysfunction; jaundice
What are the drugs used to treat hyperthyroidism?
→ the thionamides (thiourylenes; anti-thyroid drugs) - propylthiouracil (PTU) - carbimazole (CBZ) → Potassium Iodide → Radioiodine → β-blockers (for symptoms)
What are the drugs used to treat hyperthyroidism?
→ the thionamides (thiourylenes; anti-thyroid drugs) - propylthiouracil (PTU) - carbimazole (CBZ) → Potassium Iodide → Radioiodine → β-blockers (for symptoms)
How do thioamides treat hyperthyroidism?
→ inhibition of TPO (thyroid perioxidases)
→ stops T3 + T4 synthesis
→ biochemical effect = hours
→ clinical effect = weeks
What are the unwanted side effects of thioamides?
→ agranulocytosis (usually reduction in neutrophils) - rare and reversible on withdrawal of drug.
→ rashes (relatively common)
How do you follow up on a patient taking thioamides?
→ Usually aim to stop anti-thyroid drug treatment after 18 months
→ Review patient periodically including DTFT (dynamic thyroid function tests) for remission/relapse
When is iodide used to treat hyperthyroidism?
→ preparation of hyperthyroid patients for surgery
→ severe thyrotoxic crisis (thyroid storm)
How is iodide used to treat hyperthyroidism?
→ inhibits iodination of thyroglobulin
→ inhibits H2O generation + thyroperioxidase
→ inhibition of thyroid hormone synthesis + secretion
→ WOLF-CHAIKOFF effect - presumed auto-regulatory effect
→ symptoms reduce within 1-2 days
→ gland reduces in vascularity + size 10-14 days
What are the risks of a thyroidectomy?
→ Risk of voice change
→ Risk of also losing parathyroid glands
→ Scar
→ Anaesthetic
What are the names of the two thionamides?
- propylthiouracil (PTU)
- carbimazole (CBZ)
How much radioiodine is given to someone?
capsule of approx. 370 MBq (10mCi) of isotope I (131)
What are the directions of use of radioiodine?
→ contraindicated in pregnancy
→ need to avoid children + pregnant women for 10 days
What is an option of radioiodine only for scans, not treatment?
99-Tc pertechnetate
