Lecture 9 - Thyroid Disorders Flashcards
Who is more likely to get hypothyroidism?
women
typically older women?
What is our classic screening test for thyroid function?
TSH
What is the best direct measurement of free T4?
go back and PANOPTO this slide 6
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
What is the most common cause of hypothyroidism, worldwide vs in US?
worldwide = Fe deficiency
US = Hashimoto’s Thryoiditis
What are the TSH and free T4 levels for a pt with primary hypothyroidism?
TSH - elevated
Free T4 - low
What should you suspect for a pt with elevated TSH and normal free T4?
subclinical hypothyroidism
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
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
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
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
What defines overt hyperthyroidism?
elevated free T4, T3 or both
with subnormal TSH
How do the HTNs differ between hyper and hypothyroidism?
Hyper = systolic HTN
Hypo = diastolic HTN
How can you measure the potential proptosis in pts?
Exophthalmometer
normal in caucasian = 18mm
normal in AA = 22mm
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
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)
What is the treatment for thyroiditis?
propranolol
treat infection if underlying
What categories are included in the dx criterial for thyroid storm?
- Temperature
- CNS effects/Mental status
- GI dysfunction
- HR
- CHF
- A fib
- Precipitating event
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)
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)
