thyroid (SOME) Flashcards
sx of hypothyroidism
hypoactivity: fatigue, depression, cognitive impairment,
cold intolerance
wt gain
dry skin, coarse hair, dry brittle nails
lateral eyebrow thinning
constipation, menorrhagia,
exertional dyspnea,
delayed DTR
sx of hyperthyroidism
medications that can cause hypothyroidism
lithium
amiodarone
methimazole
PTU
interferon
rifampin
how can amiodarone cause hypothyroidism?
via antithyroid action of iodine- blocking T4,3 secretion, stop TH from entering peripheral tissue
intentional etiologies of hypothyroidism
surgery
ablative (I-131)
radiation therapy
how does lithium cause hypothyroidism
impairs T4,T3 release
how does interferon cause hypothyroidism
causes sx that look like hashimotos and goes away after med is stopped
how does rifampin cause hypothyroidism
it increases levothyroxine metabolism- concern for compromised fx at baseline
which conditions would have low iodine uptake on radioactive uptake scan?
thyroiditis
drug induced (iodine, amiodarone, TH)
how can amiodarone cause hyperthyroidism? (two types)
type 1: excess hormone synthesis
type 2: damage thyroid cells causing T3,T4 release
how does iodine excess cause hyperthyroidism
via Jod-Basedow phenomenon
Free T4 levels in T3 thyrotoxicosis
normal or low
thyrotoxicosis vs hyperthyroidism
they are used interchangeably BUT
thyrotoxicosis is when theres too much thyroid hormone in body in general while hyperthyroidism is excess from the thyroid gland
how estrogen affects “total” labs
increases total T4 and T3 bc of increased TBG
even tho thyroid function is actually ok
how illness affects “total” labs
decrease total T3 and T3 d/t decreased protein levels
even tho thyroid function is actually ok
4 types of thyroid cancer
papillary thyroid cancer
follicular carcinoma
medullary carcinoma
anaplastic carcinoma
what is the most common type of thyroid cancer?
papillary thyroid cancer
which thyroid cancer has the best prognosis?
papillary thyroid cancer
which thyroid cancer has the worst prognosis?
anaplastic carcinoma– 100% mortality!!
which two thyroid cancers are treated with thyroidectomy, RAI w/ I-131 and TSH suppression?
papillary thyroid cancer
follicular carcinoma
how does papillary thyroid cancer metastasize?
lymphatics
how do you monitor papillary thyroid cancer
neck US
thyroglobulin levels
I-131 metastatic surveys
PET scans
what does the prognosis of follicular carcinoma depend on?
extent of extrathyroidal extension and vascular invasion
in general it has a good prognosis
how does follicular carcinoma metastasize?
hematogenously
which variant of follicular carcinoma may be more aggressive?
hurthle cell variant
what are the two types of medullary carcinoma?
sporadic and familial
which type of medullary carcinoma is more common?
sporadic
which of the medullary carcinomas has C cell hyperplasia?
familial medullary carcinoma
what procedure improves prognosis for familial medullary carcinoma?
prophylactic thyroidectomy
what genetic screening can be done for both types of medullary carcinoma?
germ line mutation of RET oncogene
how does medullary carcinoma metastasize?
early before tumor is palpable
why dont we use R-131 to treat medullary carcinomas?
bc the rumors are not iodine avid
tx for medullary carcinomas
thyroidectomy
neck dissection
what is the serum marker for medullary carcinoma? how can you diagnose it?
calcitonin
diagnosed with FNA
which type of thyroid cancer is rare and more common in elderly?
anaplastic carcinoma
tx for anaplastic carcinoma
palliative care
how does anaplastic carcinoma tend to present
rapidly expanding, fixed, hard thyroid mass
which cancer can be seen as a late de-differentiation of papillary thyroid carcinoma?
anaplastic carcinoma
what supplement should be held before getting TSH levels? for how long?
Biotin for 2-3 days
abbreviation for TSH receptor antibodies
Anti-TSHR
TRab
abbreviation for thyroid peroxidase antibody
TPO Ab
what is the gold standard for evaluating thyroid nodules?
fine needle aspiration (FNA)
which type of nodule should you never stick a needle in?
hot nodules
which type of nodule should undergo FNA biopsy? why?
cold nodules
they are more likely to be cancerous
what is a hot nodule?
hyperfunctioning nodules that take up more of the isotope compared to normal thyroid tissue
which type of nodule is more likely to be cancerous?
cold nodules
what are cold nodules?
non-functioning nodule
they take up less isotope
in general, thyroid US are useful for..
finding out the size and texture of the gland and nodules
how big must a nodule be to biopsy it?
1cm
which screening procedure cannot differentiate follicular adenoma from follicular carcinoma?
fine needle aspiration
what is the initial diagnostic study in euthyroid nodular disease?
fine needle aspiration
when can you get a thyroid scan Tc99?
if TSH is low or FNA shows evidence of follicular neoplasia
what is a warm nodule?
functioning with similar risk of malignancy as cold nodule
what can cause a falsely low uptake with I-131?
iodine exposure
if theres a nodule, you check TSH and its high or low, whats the next step in evaluation?
I-131 uptake and scan
