Thyroid CIS Flashcards
in absence of iodine during fetal development, biosynthesis of which hormone is inhibited resulting in a short stature, potbelly and protruding tongue
thyroid hormone
What is the result or endemic iodine deficiency
cretinism
what occurs if thyroid hormone is not replaced within days of birth
mental retardation
What is the cause of graves disease
hyperthyroidism, continuous production because not under control
What are the facial characteristics of hypothyroidism
swelling
gain weight
decrease in metabolic rate
What influences amount of T4
amount of hormone and TBG
If there are changes in TBG are there changes in free T4
no
What is the most valid and useful assessment of thyroid function
serum TSH
Which part of pituitary is TSH indicative of
anterior
what is thyrotoxicosis
hyperthyroidism
What forms of thyroid hormone are increased in hyperthyroidism
increased T3 and T4
The autoAb in Graves cause what
stimulate TSH–>secretion of thyroid hormone
what is factitious thyrotoxicosis
low thyroglobulin with exogenous thyroid hormone
What is toxic adenoma
overproduction of thyroid hormone by nodule with low TSH and gland atrophy surrounding nodule
What is characteristic of viral subacute thyroiditis
painful gland
Describe silent thyroiditis
subacute lymphocytic, non tender gland, transient
seen post-partum
When do you see elevated TSH and T4
adenoma of ant pituitary
describe distribution of radioactive iodine in someone with hyperthyroidism
out of plasma fast and thyroid takes up a lot of it
What happens to distribution of radioactive iodine in hypothyroidism
not taken up by thyroid, alot more in urine and takes longer to get out of blood
What are TSH levels like in someone with nodules overproducing thyroid hormone
low TSH levels because of negative feedback
What is the demographic of Graves disease
more common in women age 20-40
What is the triad of graves disease
hyperthyroidism (dec TSH, inc T3T4 and thyroid size)
infiltrative opthalmyopathy with exophthalmos
localized, infiltrative dermopathy (pretibial myxedmea) swelling of shins
What is Tx for Graves
immune suppression, Ab clearance, blocking thyroid function, gland removal (radioactive iodine obliteration)
What areas can you lose control of that can lead to hypothyroidism
thyroid gland- primary
pituitary- secondary
hypothalamus- tertiary
tissue Resistance- rare
What is the most common primary hypothyroidism
Hashimotos (T cell mediated)
or radioactive ablation of thyroid (surgery)
What causes secondary hypothyroidism
pituitary insufficiency
What causes tertiary hypothyroidism
hypothalamic disease
What is the demographic of hashimotos thyroiditis
women 45-65
clusters in families
Describe hashimotos mechanism
T cell mediated with presence of Ab against TGB and thyroid peroxidase, TSH Receptor and iodine transporter
What is the classical presentation of hashimotos
goiter, skin change, peripheral edema, constipation, headache, fatigue and anovulation
Describe lab values of hashimotos
increased TSH and TRH
decreased T3 and T4
What is the Tx of hashimotos
replacement therapy with levothyroxine T4
Where is TGB synthesized
in follicular cells
Where is thyroid hormone stored
in the colloid part of the gland
The absence of iodine for extended period of time results in which changes on TSH, T4 and T3
decreased T3 T4
increased TSH because of feedback from no T3 T4
Administration of thyroid hormone to patient with hypothyroidism has what effect
decrease TSH levels
What does pulse, BP and weight look like in someone with hyperthyroidism
increase pulse, increase BP and decrease in weight because increased metabolism
What is the main use for radioactive iodine scan helpful for
differentiate hyper vs hypothyroidism
What type of hypothyroid deficiency is caused by Sheehans(ischemia to ant pituitary)
secondary hypothyroidism
extremely high TSH, low free T4 high prolactin and enlarged pituitary gland
probable diagnosis?
hypothryroidism
What would you see in thyroid levels with median eminence laceration
high prolactin because loss of dopamine
also have loss of TSH because no TRH communication
an HIV + male with pneumocytisis carinii has low T4 low T3 and normal TSH
what is the endocrine Dx?
Euthyroid sick syndrome
What is TSH levels in primary hypothryoidism
high
What is TSH in secondary hypothyroidism
low
What are the thyroid levels in someone with thyroid hormone Resistance
low TSH T3 and T4
What happens in the severe phase of euthyroid sick syndrome
T3 drops majorly
T4 and FT4 drop moderately
TSH increases
rT3 increases a bunch
If TGB levels are elevated as well as total thyroxine and normal TSH what is the most likely Dx
normal thyroid function because TSH in normal range
how does the thyroid hormone R work
binds cytoplasmic R and the hormone R complex diffuses into nucleus to affect transcription
if patient has low BMI
TSH normal
elevated rT3
suspected anorexia, probable?
reverse T3 has little biological effect
