Thyroid Flashcards
What are the 3 treatment goals for Hypothyroidism?
- Provide exogenous thyroid hormone
- Normalize TSH and FT4 level
TSH - 0.4–4.2 microIU/dL
FT4 - 0.8 – 2.3 ng/dl
FT3 - 1.4 – 4.2 ng/dL - Minimize symptoms and long term consequences
In general, what is the drug of choice for a hypothyroid patient?
Levothyroxine
Syntheric T4
List 3 dosing facts for Thyroid replacement medication.
What do we monitor with these?
Dose : Adjust q 6 Weeks. Take in AM or bedtime. Take on EMPTY STOMACH
Monitor- TSH and FT4 @ baseline and q6-8 weeks until normal… then Q 6-12 months.
Describe some of the adverse effects of Thyroid Replacement medications
Excessive thyroid S/Sx:
Worsening CARDIAC function and decreased BONE Density
Describe the four thyroid replacement drugs and associate them with their type
Liothyronine – Synthetic T3
Levothyroxine – Synthetic T4
Liotrix – Synth T3:T4 @ 4:1 ratio
Dessiccated thyroid – Animal sources
Give bolded information for each of the four Thyroid Replacement drugs from the slideshow
Liothryonine – Requires MULTIPLE daily doses, nich for pts who cant convert t4 to t3.
Levothyroxine – drug of choice, long half life (7 days)
Liotrix – no clinical advantage
Dessicated thyroid AKA Thyroid USP – Highest risk of hypersensitivity, concentration varies.
What is a Myxedema coma? How do we treat this?
Myxedema coma = acute complication/end state of untreated hypothyroidism. Loss of brain function presented as weakness, stupor, hypothermia, hypoventilation, hypoglycemia, hyponatremia, shock and death.
Tx: 1. Levothyroxine daily and 2. Hydrocortisone Q8hrs until coexisting adrenal suppression ruled out.
What causes Thyrotoxic crisis (Thyrotoxicosis)
Excessive quantities of thyroid hormone
What is a Thyroid Storm?
Life threat emergency - Decompensated THYROTOXICOSIS, fever, tachycardia/pnea, dehydration, delirum, coma, n/v, diarrhea
Exopthalmos is commonly associated with what disorder?
Graves (50% of graves patients)
What is the treatment of choice for a NON-PREGNANT, patient over 21 with Grave’s, multinodular goiter or toxic adenoma?
Radioactive Iodine (ablation), most cost effective… Try pharmacology first
Who should not get Radioactive Iodine?
Graves patient with MODERATE or SEVERE EXOPTHALMOS
Pregnant or nursing female
If somebody has SEVERE hyperthyroid (>80gms), Is unwilling to take meds, or is pregnant, what is the treatment of choice?
Partial or total THYROIDECTOMY
Almost all (80-90%) will become hypothyroid
What patients should get Anti-thyroid pharmacotherapy for hyperthyroid?
- Pts with significant symptoms of mild disease/small goiters… likely to achieve remission after 1 year
- Pts who refuse ablative or surgical therapy
- Ablative or surgical therapy fails
- Limited life expectancy or MOD-SEVERE exopthalmos
What are some general timeline and relapse characteristics of Anti-Thyroid Pharmacotherapy?
Requires 12-18 months of tx
50% chance of relapse
Describe our four classes of Anti Thyroid medications (including ablative therapy)
- Thionamides - PTU/Methimazole block synth
- Iodides - Potassium Iodide blocks release
- Radioactive isotope - Sodium Iodide ablates gland
- Adrenergic blockers - B blockers control symptoms
Describe the thioamide/thionamide class of drugs including specific meds, and MOA
Meds : Propythiouracil and Methimazole
MOA - inhibits THYROID PEROXIDASE = blocks iodination and synth of thyroid hormones (can also blcok t4-t3 conversion)
Methimazole is the preferred agent in _________ disease unless in the _______ trimester of pregnancy
Grave’s disease
First
Propythiouracil (A thioamide) is use for what patients?
First trimester
Thyroid storm
or adverse reactions to Methimazole
Describe the efficacy and onset for thioamide drugs
Slow onset (weeks) 3-8 for euthyroid... max effect 4-6 months. Remission rates of 20-30% (norm for 1 year after discontinue)
What labs should be monitored with thioamide drugs? Why?
Baseline CBC w/ diff and LFTs with bili.
Watch for agranulocytosis and Jaundice
Should a radioactive iodide and thioamide be given together?
No, discontinue thioamide at least 3-5 days before admin of radioactive iodide.
Iodine therapy can ______ onset of thioamide therapy
delay
What is the black box warning for Thioamides? What are other adverse effects?
Sever liver injury and acute liver failule.
Also causes jaundice, agranulocytosis (stop), leukopenia (OK), lupus like symtpoms (stop), rash (OK)
Iodides acutely ______ hormonal secretion of thyroid within _________
Inhibit
Hours
Is iodine a permanent solution to hyperthyroid?
No, it is temportary. It prevents the usage of iodine by THYROID PERIOXIDASE
When the thyroid escapes iodide inhibition and has a surge of t3 and t4 release, what do we call this?
Escape from the Wolff-Chaikoff effect.
Iodides ______ the thyroid gland’s vasculatiry, Increase ________, and decrease ______ prior to thyroidectomy
decrease
Firmness
size
Why and when would we give a patient an Iodide?
- PREOP prep for thyrodectomy in graves
- Thyroid blocking to protect gland before RADIATION exposure
- Hyperthyroid pts w/ Toxic Adenoma or Toxic Nodular goiter
- Severe Hyperthyroidism or THYROID STORM
- Patient w/ Graves in region w/ IODINE Deficiency
Discontinue all ____________ medications at least 3-4 days prior to sodium iodide admission
Anti-thyroid medication
Also, watch out for lithium
How does a radioactive iodine work to ablate the thyroid?
Accumulates in the thyroid and emits beta and gamma rads. This destroys thyroid tissue. Takes 2-6 months. May need 2 doses
What monitoring must we do with Radioactive iodine?
Neg preg test 48 hours prior
TSH and FT4 q 4-6 weeks
What adverse effects are we worried about with radioactive iodine?
Hypothyroidism (permanent in 80% patients)
Hurts fetus/baby
Thyroid pain
Do we like selective or non-selective Beta blockers for hyperthyroidism?
Non selective. Think Propranolol
If Beta blockers are contraindicated but we need to relieve tachycardia from a hyperthyroid patient, what should we give?
Non-DHP calcium channel blockers –> Verapamil or Diltiazem
Amioderone can cause what thyroid side effect?
Amiodarone induced Thyrotoxicosis.
What is the fever cutoff for a thyroid storm?
103+
Describe our 6 step management of thyroid storm
- Suppress NEW HORMONE synth*** - PTU or methimazole
- Block release of thyroid hormone - after 1 hour from step 1, give potassium iodide drops
- Antiadrenergic therapy - Propranolol or esmolol for asthma/diltiazem
- Acetaminophen - fever and bp stable
- Corticosteroid - hydrocortisone
- Bile acid sequestrant - no recycle TRH - Cholestyramine
