Lecture 9 - Thyroid Disorders Flashcards by Indy P

Who is more likely to get hypothyroidism?

women

typically older women?

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What is our classic screening test for thyroid function?

TSH

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What is the best direct measurement of free T4?

go back and PANOPTO this slide 6

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What is the difference between primary, secondary, and subclinical hypothyroidism?

Primary - high TSH with low free T4

Secondary - low T4 and TSH that is low or normal

Subclinical - normal T4 with elevated TSH

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What is the most common cause of hypothyroidism, worldwide vs in US?

worldwide = Fe deficiency

US = Hashimoto’s Thryoiditis

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What are the TSH and free T4 levels for a pt with primary hypothyroidism?

TSH - elevated

Free T4 - low

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What should you suspect for a pt with elevated TSH and normal free T4?

subclinical hypothyroidism

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A pts lab results are normal TSH with low free T4, what is on your ddx?

secondary hypothyroidism

but this is super rare so consider redrawing their labs again

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For a patient with subclinical hypothyroidism, should they be treated?

T4 replacement is made on a case by case basis and depends partly upon the degree of TSH elevation

since they antibodies they might get worse hypothyroidism overtime

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Levothyroxine

the half life of this medication is long so you have to wait for the med to build up before you can test the level —-4 - 6 weeks after dose change

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What do you tell a pt who is taking levothyroxine, in regards to when to take it and what to do if you forgotten to take a pill?

take the medication on an empty stomach

don’t eat for an hour
also if they are taking Ca or iron, don’t take those within 4 hours of taking levothyroxine

if they have forgotten a pill, take 2 the next day

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What defines overt hyperthyroidism?

elevated free T4, T3 or both

with subnormal TSH

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How do the HTNs differ between hyper and hypothyroidism?

Hyper = systolic HTN

Hypo = diastolic HTN

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How can you measure the potential proptosis in pts?

Exophthalmometer

normal in caucasian = 18mm
normal in AA = 22mm

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You suspect that your pt has hyperthyroidism, you are going to refer them to endocrinology, but first what labs should you do?

TRAb - autoantibodies to the TSH receptor
TSI - thyroid stimulating immunology
TBII - thyrotropin - binding inhibitory immunoglobin

board questions might want you to say nuclear medicine uptake and scan but this is expensive

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How do you treat hyperthyroidism/Grave’s?

to help with their sxs while they wait for endocrine referral

if they have tachycardia - propranolol bid (they clear the medication faster)
(also helps block T3 conversion)

Methimazole (instead of PTU d/t liver problems)

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What is the treatment for thyroiditis?

propranolol

treat infection if underlying

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What categories are included in the dx criterial for thyroid storm?

Temperature
CNS effects/Mental status
GI dysfunction
HR
CHF
A fib
Precipitating event

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What should you be thinking as a ddx if you have a pt you are treating with hormone replacement that is doing better and then all of the sudden tanks?

adrenal insufficiency? (other autoimmune disorders)

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Graves Disease

Autoimmune attack of the TSH receptor antibodies (TRAB) –activating them
HypERthyroidism (MC cause)

sxs:
ophthalmopahty - exopththalmos, proptosis 
pretibial myxedema (notpitting edema) 
tachycardia
hyperglycemia 
HTN (typically systolic) 
heat intolerance

Dx:
TSI (thyroid stimulating immunoglobins) 
low TSH 
high T3, T4 
Nuclear medicine uptake and scan (RAIU) - iodine dye --more uptake in the graves thyroid

tx:
Radioactive Iodine
BB (propranolol) - this decrease tachycardia AND blocks the conversion of T4 to T3
Methimazole - blocks thyroid hormone production

Thyroidectomy - last resort or if pt is pregnant or plans on getting pregnant in the next 6 months (or males want to father in the next 6 months)

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How do you dx Graves dz?

TSI (thyroid stimulating immunoglobins)
low TSH
high T3, T4
Nuclear medicine uptake and scan (RAIU) - iodine dye –more uptake in the graves thyroid

How do you tx Graves dz?

Radioactive Iodine

BB (propranolol) - this decrease tachycardia AND blocks the conversion of T4 to T3

Methimazole - blocks thyroid hormone production

Thyroidectomy - last resort or if pt is pregnant or plans on getting pregnant in the next 6 months (or males want to father in the next 6 months)

What are causes of hyperthyroidism?

Graves disease (MC)
Toxic Multinuodular Goiter
TSH secreting pituitary adenoma
Excess intake of T3 or T4

What are causes of hypothyroidism?

Iodine deficiency
Hashimotos thyroiditis
postpartum thyroiditis
post radioiodine treatment for hyperthyroidism

What are the sxs of hypothyroidism?

``` cold intolerance weight gain goiter myxedema hypoactivity - fatigue, sluggishness, depression hoarseness of voice bradycardia HTN, typically diastolic hypoglycemia ```

What are the sxs of hyperthyroidism?

``` Heat intolerance weight loss goiter easy bruising anxiety fine tremors fatigue urinary/deification urgency tachycardia palpitations hyperglycermia scanty periods (oligomenorrhea) HTN - systolic ```

Thyrotoxicosis

thyroid hormone excess - not the same thing as hyperthyroidism

What are the criteria for thyroid storm?

``` temperature CNS effects/mental status GI dysfunction HR CHF Afib precipitating event ```

Thyroid storm

potentially fatal (10-30% mortality) complication of untreated thyrotoxicosis after a precipitating event (surgery, trauma, infection, illness, pregnancy) sxs: hypermetabolic state- palpitations, tachycardia, A.fib, high fever, N/V, psychosis, tremors dx: decrease TSH, increase T4/T3 tx: PTU or methimazole (remember that PTU has bad liver SE) BB IV glucocorticoids (hydrocortisone, prednisone, dexamethasone)

What is the MC cause of hypothyroid in US?

Hashimotos thyroiditis W > M

Hashimotos thyroiditis

MC cause of hypothyroidism self destruction of thyroid follicle cells painless, enlarged goiter (d/t in TSH) hypothyroid sxs Thyroid Ab present tx: levothyroxine (synthetic T4)

Levothyroxine

synthetic T4 given to hypothyroid pts dont take within 1 hour of food or 4 hours of Ca/Fe pills check TSH levels in 6 weeks since half life is 7 days so time to reach steady state would be 30 days

What is the MC cause of hypothyroid worldwide?

idoine deficiency

If a pt presents with an asymptomatic nodule on their thyroid, what do you do?

Get US need biopsy the solid/hypoechoic nodules never biopsy cystic/fluid nodules because they are ALWAYS benign

Starry night

microcalcifications seen on some thyroids that indicates a BAD prognosis

What thyroid nodules get biopsied?

>1cm SOLID nodules

Subacute thyroiditis

aka Grandulomatous thyroiditis aka de Quervian's thyroiditis typically viral infection of the thyroid PAINFUL thyroid typically presents with hyperthyroidism even though it eventually becomes hypothyroid NO thyroid Antibodies Elevated T3/T4 tx: NSAIDS for pain and inflammation typically returns to normal in a year

What do the labs look like for a pt with subacute thyroiditis?

elevated T3 and T4

What is the treatment for subacute thyroiditis?

NSAIDS NO thyroid medications since this is a viral inflammatory problem will typically return to normal in 12 months

A pt presents with a unilateral, painful thyroid nodule, what should you be suspecting?

could be acute thyroiditis -typically caused by an infection via S. aureus

Thyroid Nodules

60% of people will have a thyroid nodule --incidence increases with age (80% women) only 5-10% are malignant US is the best initial testing solitary nodule is tumor until proven otherwise get FNA - fine needle aspiration (25 gauge needle)

Cold vs hot nodules

RIUS - radioactive iodine uptake scan hot means that the iodine was taken up (remember that the thyroid loves iodine cold (no/low iodine uptake) is highly suspicious for malignancy

Which thyroid cancer is the most common?

papillary (80%) followed by follicular

What is the biggest risk factor of papillary thyroid cancer?

radiation exposure

Who is more likely to get papillary thyroid cancer?

MC in young females (20-50 y/o) least aggressive distant METS uncommon excellent prognosis Hashimotos puts you at an increased risk of papillary carcinoma

Who is more likely to get follicular thyroid cancer?

40-60 y/o

A thyroid nodule is typically benign, unless what kind of presentation?

in a pt <20 y/o ALWAYS be suspicious of a nodule in a young pt

Medullary thyroid cancer is associated with .....

MEN 2

What is the treatment for thyroid cancer?

total thyroidectomy

Which type of thyroid has the worst prognosis?

anaplastic

Which thyroid carcinoma arises from the C cells?

medullary | Calcitonin excess production

What is measure post thyroidectomy in a medullary carcinoma to check for residual disease or recurrence?

calcitonin