1b// Hyperthyroidism Flashcards
Add how a thyroid follicular cell works…
How is the thyroid controlled?
1) Hypothalamus releases TRH (thyrotropin releasing hormone)
2) Which stimulates the pituitary to release TSH (thyroid stimulating hormone)
3) Which causes the thyroid to release thyroxine (T4) and triiodothyronine (T3)
What level of TSH will you find in a patient with primary hypothyroidism, where the thyroid gland has been destroyed by the immune system?
High TSH
When do you know what dose is correct of T4 replacement therapy?
Increase the dose until TSH falls to normal
What is Grave’s disease?
Autoimmune
Antibodies bind to and stimulate TSh receptor in the thyroid
Cause goitre (smooth and larger) and hyperthyroidism
What are symptoms of Grave’s disease?
perspiration
muscle wasting
shortness of breath
breast enlargement
loss of weight
rapid pulse
warm, moist palms
amenorrhea
localized myxedema
(nervousness, excitability, restlessness, insomnia, emotional instability)
Exophthalmos
Palpitation, tachycardia
Increased appetite
What causes exophthalmos in Grave’s disease?
Other antibodies bind to muscles behind the eye and cause exophthalmos
What is pre-tibial myxoedema, and when can it be noticed?
the swelling (non-pitting) that occurs on the shins of patients with Grave’s disease: growth of soft tissue
hypertrophy
What causes pre-tibial myxoedema in Grave’s?
other antibodies
What is myxoedema?
hypothyroidism
What is the antibody involved in Grave’s?
TSH-receptor antibody (TRab) (against the TSH receptor)
How do you measure TRab, and when do you do the test for it?
in bloodstream during Grave’s disease
it is the first-line investigation to confirm Grave’s
What is toxic nodular thyroid disease?
Single toxic nodule/ multiple toxic nodules (multinodule goitre)
NOT autoimmune
Benign adenoma(s) overactive at making thyroxine
No pretibial myxoedema or exophthalmos
Overactive thyroid
What happens to the thyroid gland during toxic nodular thyroid disease?
normal gland atrophies because there is no TSH
When does toxic nodular thyroid disease occur age wise?
older people, 50-60
What is the effect of thyroxine on the sympathetic nervous system and outcomes of it (4)?
Sensitises beta adrenoreceptors to ambient levels of adrenaline and noradrenaline.
Thus there is apparent sympathetic activation.
Tachycardia, palpitations, tremor in hands, lid lag
Symptoms of hyperthyroidism?
weight loss (despite increased appetite)
breathlessness
palpitations, tachycardia
sweating
heat intolerance
diarrhoea
lid lag and other sympathetic features
What is a thyroid storm considered medically and why?
medical emergency: 50% mortality untreated
What would the blood results from someone with a thyroid storm show?
hyperthyroidism
What are symptoms of a thyroid storm?
Hyperpyrexia (fever) >41 degrees
Accelerated tachycardia/ arrhythmia
Cardiac failure
Delirium/ frank psychosis
Hepatocellular dysfunction; jaundice
Needs aggressive treatment