Endocrine Flashcards
what level of TSH is diagnostic for overt hypothyroidism
TSH > 10
what are 2 hormone replacement products for thyroid?
Levothyroxine (synthetic T4)
-Liothyronine (T3)
What is Liotrix?
synthetic LT4 and T3 combination product - never use; unpredictable an toxic potential
what is the treatment of choice for hypothyroidism?
Levothyroxine (synthetic LT4)
between LT4 and T3, which has the longer 1/2 life?
LT4! (1/2 life is 7-10 days)
t3 1/2 life is 24 hours
when is the ONLY time to consider giving patient T3?
when they have impaired conversion of T4 to T3
Why is Armour thyroid and ratio products like Liotrix never used?
risk of toxicity and unpredictable outcomes; also no benefit when compared to Levothyroxine
what is the MOA of levothyroxine?
synthetic LT4; mimics normal physiology of thyroid gland
when do you recheck TSH levels?
6-8 weeks after initiation of levothyroxine
you see a patient 6 weeks after initiating Levo; his TSH are not yet at goal. What do you do?
change the dose by 10-20% and follow up in another 6-8 weeks
T or F: small differences in Levothyroxine can make big differences in TSH levels
TRUE
what is the biggest risk of overtreating a patient with Levothyroxine?
cardiac issues - A.fib
also depression, osteoporosis
when do you advise your patient to take their Levothyroxine?
best when taken in the EVENING on empty stomach
can also take in a.m. 1-2 hours before breakfast/other meds
to avoid drug-drug interactions, pt should take LT4 2 hours before or 6 hours AFTER to reduce the risk of interaction with which types of medications?
calcium
iron
multivitamins
prenatal vitamins
after patient is stable (euthyroid), how often should they come in for monitoring/re-checking levels
6-12 months (more often if pregnant)
T or F: always write the prescription for Levo in mg.
FALSE! correct units are mcg!
what level of TSH is diagnostic of HYPERTHYROIDISM?
TSH < 0.5
what is the most common cause of hyperthyroidism?
Graves Disease
Subclinical hyperthyroidism may become OVERT if:
iodine excess infection stress smoking lithium
Treatment Hyperthyroidism
Beta Blockers (to block palpitations, tremor, anxiety) + PUT/MMI
Specifically what type of Beta Blockers are used for treatment of hyperT
NON-SELECTIVE (propranolol or nadolol)
-these impair the conversion of T4 to T3
you’re supposed to use nonselective betablockers to treat HyperT in patients EXCEPT THOSE WITH
asthma or decompensated HF
use atenolol, clonidine, verapamil, diltiazem
What are some other methods used to reduce thyroid hormone synthesis?
Iodide, anti-thyroid drugs(PTU/MMI), radioactive iodine, surgery
What is the MOA of iodide?
blocks thyroid’s uptake of iodine, inhibiting synthesis and release of thyroid hormone
T or F: it’s ok to use iodide to treat thyroid storm BEFORE radioactive iodine treatment
FALSE!!! this will inhibit the concentration of radioactivity in thyroid, AKA thyroid won’t be able to take up the iodine
What are the 2 most common antithyroid drugs used to treat hyperthyroidism?
Propylthiouracil (PTU)
Methimazole (MMI)
MOA PTU and MMI
interferes with synthesis of thyroid hormones by interfering with iodine incorporation. Also has immunosuppressive effects (helps in Graves)
This antithyroid drug specifically inhibits conversion of T4–> T3
PTU
This medication is the primary therapy for Graves and to prepare for surgery or radioactive iodine administration
PTU/MMI
how often to monitor patient’s being treated for Graves with MMI
every 4-6 weeks until stable (then decrease to maintain euthyroid)
What is the significance of patients who are TSHR-Sab (+)
these patients almost ALWAYS relapse (Graves disease)
what is the black box warning for PTU
severe liver injury (only use if can’t tolerate MMI)
what is agranulocytosis?
decrease in WBC, presenting in first 3 months of MMI/PTU treatment as sudden fever, malaise, sore throat
-may develop sepsis and die
what to do if patient on MMI experiences agranulocytosis
D/C antithyroid drug immediately - give Abx if afebrile, and consider filgrastim
what is the option for thyroid ablation without surgery
radioactive iodine
how to manage patient while going through radioactive iodine
put them on BB and MMI; the process is slow and need to address symptoms and prevent thyroid storm in the meantime
Contraindications for MMI/PTU?
pregnancy
breastfeeding
what is the consequence of radioactive iodine treatment?
usually will develop hypothyroidism, as thyroid gets damaged. They will then need Levothyroxine
what is the 1/2 life of radioactive iodine?
8 days
how do we treat a pregnant patient for hyperthyroidism/thyrotoxicosis
PTU in 1st trimester (MMI is teratogenic here) –> then MMI in 2/3 trimesters
Which drug is safer in 2nd and 3rd trimester: MMI or PTU?
MMI
What causes thyroid storm?
radioactive iodine treatment withdrawal from antithyroid drug (MMI/PTU) infection trauma surgery
this life-threatening disorder can be caused by severe thyrotoxicosis
Thyroid storm
Treatment thyroid storm
BB + large doses PTU/MMI + APAP + antiarrhythmics
Causes of PRIMARY Hypothyroidism
autoimmune thyroid (Hashimotos
iatrogenic (surgery/radiation)
Drugs
thyroiditis (postpartum_
what is the name for the T3 product?
Liothyronine
What is the combination T4/T3 product?
Liotrix (not used in modern therapy due to unpredictable and toxic potential)
what can happen regarding the bones when we overtreat with thyroid meds?
Osteoporosis
what type of beta blocker is preferred for treating hyperT?
nonselective
propranolol or nadolol
what types of patients do you need to avoid using non=selective BB in treating Hypert
asthma
heart failure
what is radioactive iodine used for?
Given to Graves’ patients 7-14 days before surgery
also reduces hormone release during thyroid storm
when is one time to NOT use iodide for treating hyperthyroid?
before radioactive iodine treatment (use MMI)
AE iodid
gynecomastia, hypersensitivity, iodism
what medication is the best to prescribe in large doses during thryroid storm?
MMI (longer 1/2 life)
after you reach euthyroid in treating apatient with hyperthyroidism, what do you do next?
decrease the dose, overtreating leads to hypothyroid
what is the black box warning of PTU
severe liver injury w/ PTU (only use if can’t tolerate MMI)
what is the MOA of radioactive iodine?
produces thyroid ablation without surgery
treating a patient with radioactive iodine is a SLOW process; what do you administer in the meantime?
BB + MMI (to address symptoms and prevent thyroid storm)
when is radioactive iodine contraindicated?
pregnancy and lactation
your patient is newly pregnant and being treated for her hyperthyroidism. What medication should she start on in the 1st trimester?
PTU is safest in 1st trimester; switch to MMI during 2nd and 3rd trimesters
a patient comes into the ED with high fever, tachypnea, tachycardia, severely dehydrated. you suspect Thyroid storm. What is the treatment of choice?
BB + LARGE dose MMI + APAP, antiarrhythmics, IV hydrocortisone
which 4 drugs can cause thyroid disease?
Amiodarone (hypo/Hyper)
Lithium (hypoT)
Interferon-alpha (hypo)
tyrosine kinase
regarding drug-induced thyroid disease, what would a patient be using interferon alpha for and how would you manage the new onset thyroid issue it caused?
taking it for Hepatitis C; start them on Levothyroxine (LT4) and re-evaluate in 6 months
A patient is taking tyrosine kinase inhibitors, and can develop thyroid disorder. What would they be taking this for?
cancer, including thyroid cancer
imatinib
(sunitinib)
Sorafenib)
There are 2 systemic glucocorticoids used to treat chronic adrenal insufficiency. What are they?
Hydrocortisone (short 1/2 life)
Prednisone (long half life)
How do you treat a patient with addisons disease?
need mineralcorticoid replacement (Fludrocortisone)
You are seeing a patient for Cushing’s syndrome; how do you handle this if it’s due to medication vs. tumor?
REMOVE TUMOR or D/C steroids gradually
what are the 2 drugs used for inhibitors of adrenal steroidogenesis (cushings)
ketoconazole
Metyrapone
MOA metyrapone
reduces cortisol and corticosterone production (suppresses aldosterone synthesis)
MOA: Ketoconazole
antifungal; blocks enzymes in steroid biosynthetic pathway
Adverse effects of ketoconazole
gynecomastia, decreased libido, adrenal insufficiency, hepatotoxicity
T or F: ketoconazole works slow
FALSE - works fast
if adrenal steroidogenesis inhibitors are not tolerated for treating Cushings, there is an adrenolytic agent. What is its name
Mitotane
MOA mitotane
inhibits steroidogenesis at LOW DOSES (adrenolytic at high dose)
Steroid tapering is only necessary if used longer than
> 3 weeks
How do you taper a steroid for patients?
stable decrease of 10-20% dose
what are the 3 classes of medications used to treat acromegaly?
Somatostatin analog
GH receptor antagonists
Dopamine agonists
acromegaly is caused by overproduction of GH, often caused by ___
pituitary adenoma
Octreotide
Lanreotide
Somatostatin analogs (Acromegaly)
MOA octreotide/Lanreotide
Inhibits GH by binding somatostatin receptors in pituitary; reduces pituitary tumor size
what is the name of the GH receptor antagonist?
Pegvisomant (blocks action of GH)
we already know that bromocriptine is a dopamine receptor agonist - what is the other one used in GH oversecretion?
Cabergolamine (better tolerated)
contraindications of dopamine agonists?
uncontrolled HTN, ischemic disease, PVD
you are seeing a patient who is thinking about trying to get pregnant. She is taking Cabergolamine. What do you advise?
she needs to stop this 1 month before conception (it has a long 1/2 life)
what is the treatment for GH deficiency?
Somatotropins (omnitrope, nutropin, Humatrop)
when is the best time to administer (inject) somatotropins?
in the evening, as most of GH secretion occurs during sleep
contraindications of somatotropin
cancer/tumors
prader-willi syndrome
obese
respiratory impairments
thyroid hormones are important for:
fetal growth and development, regulation of energy metabolism
iodism is an adverse effect of iodide treatment. What does this look like?
palpitations, depression, weight loss, pustular skin eruptions