hyperthyroidism Flashcards
Grave’s symptoms
exophthalmos
muscle wasting
face flushing
localised (pretibial) myxoedema
what is pretibial myxoedema (compared to myxoedema)
swelling (non-pitting) on shin of pt’s with graves (growth of soft tissue)
myxoedema =hypothyroidism
what is grave’s
autoimmune
ab binds to and stimulate TSH receptor in thyroid
TSH- receptor antibody
(TRAb measured in bloodstream)
TSH-receptor antibody test can also used as investigation
diffused smooth goitre and uniform radioiodine uptake
toxic nodular thyroid disease
What it is
Symptoms
Scan result
Single toxic nodule/multiple toxic nodules (multinodular goitre)
NOT autoimmune
Benign adenoma(s) overactive at making thyroxine.
NO pretibial myxoedema
NO exophthalmos
shows hot nodule in radioiodine uptake scan (one sided only)
What thyroxine do to sympathetic nervous system and effects/symptoms
Sensitises beta adrenoceptors to ambient levels of adrenaline and noradrenaline.
sympathetic activation
Tachycardia, palpitations, tremor in hands, lid lag
hyperthyroidism symptoms
Weight loss despite increased appetite
Breathlessness
Palpitations, tachycardia
Sweating
Heat intolerance
Diarrhoea
Lid lag and other sympathetic features
thyroid storm symptoms
Hyperpyrexia > 41oC
accelerated tachycardia / arrhythmia
cardiac failure
delirium / frank psychosis
hepatocellular dysfunction; jaundice
thyroid hormone synthesis
- uptake of iodine via active transport
- iodination
- coupling reaction: storage in colloid
- endocytosis and secretion
4 treatment for hyperthyroidism
- thionamines (anti-thyroid drug)- can give in pregnancy
- potassium iodine
- radioiodine
- beta-blockers
examples of thionamide drugs
mechanism of action?
side effects?
follow up?
1.propylthiouracil (PTU)
carbimazole (cbz)
2.inhibit thyroid perioxidase and hence T3/4 synthesis and secretion
biochem effects=hours
clinical effects= weeks
- rare but reversible on drug withdrawal= agranulocytosis (reduction in neutrophils)
common=rashes - stop anti-thyroid drug after 18 months
review periodically for relapse
role of beta blockers in thyrotoxicosis
ie propranolol- reduce symptoms ie reduct tremor, slow heart rate, less anxiety
iodone (KI)- what is it for? MOA? time for effect?
what: prep for surgery
thyroid storm
MOA: inhibit iodination of thyroglobulin, H2O2 generation and thyoperioxidase
symptoms reduced in 1-2 d
gland size reduce in 10-14 ds
Wolff–Chaikoff effect=
reduced thyroid hormone levels from iodine ingestion
thyroid surgery risk (thyroidectomy)
voice change (recurrent laryngeal nerve)
losing parathyroid gland
scar
anaesthetic
radioiodine- how to uptake? Who to avoid? What is it for?
Swallow a capsule of iodine isotope
avoid in pregnancy
Need to avoid children and pregnant mums for a few days
For scans only (not treatment)
radioiodine only collects in thyroid gland and destroys the tissue- could cause hypothyroidism but that is easier to manage with drugs than hyperthyroidism/Levothyroxine.
