hyperthyroidism W6 Flashcards
commonest cause of primary hyperthyroidism? what occurs in this condition?
Graves Disease (75%)
autoimmune disease, antibodies attack thyroid to make it overactive. can be associated with eye disease.
smooth goitre with uniform increased uptake on scintigraphy
what is scintigraphy?
gamma scan
what accounts for 15% of primary hyperthyroidism? what occurs in this condition?
toxic multinodular goitre
multiple lumps (nodules) on enlarged thyroid (goitre)
often one or more lumps will be overactive
can get lid lag or lid retraction, but no other features of thyroid eye disease
isolated hot-spots between dark spots on scintigraphy
what is lid lag or lid retraction a result of?
activation of the sympathetic nervous system
links between age and thyroid gland?
as age increases glands become progressively more nodular. can cause compression of trachea. can get elevation of T3 and T4
other causes of primary hyperthyroidism (other then Graves disease or toxic multinodular goitre)
toxic nodule (single lump)
thyroiditis (temp overactivity, can be followed by underactivity)
what can trigger thyroiditis?
pregnancy, infection, drugs
symptoms of hyperthyroidism?
weight loss (despite good appetite - often very hungry)
tiredness
tremor, palpitations, hot/sweaty (activation of symp system)
diarrhoea
light/absent menses (menstrual blood)
irritable/anxiety
eye problems
muscle weakness
eye problems in hyperthyroidism?
change in appearance
red
gritty
painful
double vision
muscle weakness is particularly prominent in which muscles in hyperthyroidism?
large proximal muscles of the thigh
hyperthyroidism - points to focus on when taking a history?
PMH and meds - asthma, heart disease
FH - thyroid or other autoimmune disease
SH - smoking, job and family
examination for hyperthyroidism?
agitated, talk fast
warm, sweaty
temor
increased heart rate, may be atrial fibrillation
smooth goitre (Graves) vs MNG vs single nodule vs no goitre (thyroiditis)
bruit heard over goitre almost diagnostic of graves
eyes
bruit?
increased vascular supply causes rushing noise
eye examination for graves disease?
non specific to graves - lid retraction and lag
specific to graves:
redness
gritty sensation
dry/watery eyes
pain on eye movement
swelling around eyes
proptosis
double vision
loss of colour vision
proptosis?
pushed forward appearance of eyes
pathogenesis of eye disease in graves disease?
beta cells produce TSH receptor antibodies which bind with receptors in retro orbital connective tissue. this affects adipocytes and fibroblasts. adipocytes produce new fat (adipogenesis). fibroblasts produce glycosaminoglycans retain more water. this oedema and increased fatty tissue contribute to swelling in muscles and tissues behind eyes, leading to symptoms.
conjunctive redness categories?
mild - 25% of whites of eyes or less
moderate - up to 50%
severe - over 50%
eyelid/periorbital swelling types?
fluid swelling
non-fluid swelling (caused by fatty tissue)
eyelid/periorbital erythema
definition and types?
redness of eyelids
pretarsal - bit that closes over eye
preseptal - further out around eyelid
swelling of the plica/caruncle?
areas in medial aspect of eye (corner of eye closest to nose)
caruncle - white structure
plica - red structure (fold)
primary hyperthyroidism diagnosis?
TRAbs (TSH receptor antibodies) - significantly positive indicates Graves
TPO (thyroid peroxidase) - less specific
if TRAbs negative then do scintigraphy (often technetium rather than radio-iodine uptake)
management of hyperthyroidism - drugs?
antithyroid drugs (ATDs) - carbimazole and propylthiouracil (PTU)
both block thyroid peroxidase activity.
scintigraphy - why does technetium benefit over radio-iodine uptake?
less radiation
when are carbimazole and propylthiouracil not used for hyperthyroidism? why?
not used for thyroiditis.
high T4 levels are due to release of hormone stores from damaged gland, but gland is not actually overactive.
