Week 1 Endocrine- thyroid Flashcards
What lab values would indicate hypothyroidism?
TSH greater than >10
T4 less than <9
What lab values would you see in subclinical Hypothyroidism?
TSH elevated from 4-10
T4 & T3 are normal
What is the treatment of choice for hypothyroidism?
replacement therapy is achieved with
Levothyroxine (L-T4)
The goal is to normalize the TSH level, replacement dose is 1.6mcg/kg/day
When would you prescribe Liothyronine (Triiodothyronine - T3) ?
its used for short term management of patients with thyroid cancer undergoing withdrawal of L-T4 WHEN recombinant TSH is not an option, in order to prepare for radioactive iodine therapy
How can Levothyroxine dose be impaired ?
- Absorption may be reduced by antacids
- calcium salts
- Cholestramine
- iron tablets
so separate the dose by 6 hours
an increase in TSH is also possible with:
- PPI
- estrogen
When will you check TSH lab values after starting treatment for hypothyroidism?
wait 6- 8 weeks
Your patient has hypothyroidism and is taking levothyroxine. She is considering getting pregnant, what should you do?
Hypothyroidism is associated with infertility and miscarriage
Women who are on thyroid hormone replacement should have a preconception TSH measurement done to ensure it is normalize
In the first trimester TSH levels are low due to high beta hCG levels
IF a woman’s first trimester TSH level is not suppressed this may indicate under-treatment with levothyroxine or a new diagnosis of hypothyroidism,
if your patient has hypothyroidism and finds out they are pregnant what should they do?
they should immediatley increase their thyroid hormone dose by two extra tablets per week following a positive pregnancy test
during pregnancy in women with hypothyroidism, how often are you monitoring TSH levels?
monitor TSH q4 weeks for the first half of the pregnancy and at least once during the second half of pregnancy
what drugs can induce hypothyroidism?
amiodarone
Lithium
what are some side effects of Levothyroxine (LT4)
AE: increase heart rate, anxiety, tremors
- it decreases bone mineral density
what is the first line treatment for hyperthyroidism?
Methimazole (MMI), it inhibits TH synthesis
if your patient has hyperthyroidism and is pregnant how would you treat them?
1st trimester: PTU
2nd & 3rd trimester: MMI
in the first trimester MMI can cause craniofacial malformations
What are some side effects that can arise from taking MMI for hyperthyroidism?
AEs include:
- neutorpenia
- cholestatic jaundice
what are some adverse effects that can arise from taking PTU?
- neutropenia
- liver injury, hepatitis or liver transplant
What is myxedema coma?
This is a rare severe state of decompensated hypothyroidism, usually the result of untreated hypothyroidism in the elderly
symptoms include hypotension, and decreased LOC
patients are treated with levothyroxine 300-400mg IV, followed by daily 100mcg LT4 and hydrocortisone 100mg Q8 hours
What is graves disease?
its an autoimmune disorder that stimulates the thyroid gland to produce more T3/T4 causing hyperhyroidism
typically TSH levels are suppressed and T4 levels are elevated
what dosing would you use to treat hypothyroidism in elderly patents with cardiovascular risk factors?
Start with a low LT4 dose 12.5 to 25 mcg/ day
higher doses are associated with fractures
