Lecture 18: Thyroid Disorders Part 2 Flashcards
What is thyrotoxicosis?
State of excessive T3/T4.
What is hyperthyroidism?
A state of increased thyroid function.
What is the most common demographic for hyperthyroidism?
Women > 60, esp if they smoke.
Same as hypothyroidism as well.
What is the MCC for thyrotoxicosis?
Graves disease (60-80%)
What is Graves Disease?
Autoimmune disorder in which autoantibodies bind to TSH receptors, causing excessive thyroid function.
What tests can be positive for Graves Disease?
- Thyroid stimulating Ig (TSI, 65% +)
- Anti-TPO (75% +)
- Anti-Tg (55%)
When is the most common onset of Graves Disease?
Women ages 20-40
What are TSI tests used for?
Assisting in the diagnosis of Graves Disease.
What is the first line test to check for Graves?
TSH/FT4/Thyroid panel
What can interfere with TSI lab tests?
Radioactive iodine
What are the common etiologies for excessive iodine in thyrotoxicosis?
- Iodinated radiocontrast dye
- High-iodine foods (kelp, nori)
- Potassium iodine, amiodarone, povidone iodine
What types of thyroiditis can cause thyrotoxicosis?
- Infectious/subacute
- Silent/postpartum
What are the general symptoms for thyrotoxicosis?
- Fatigue and weakness
- Weight loss with increased appetite
- Nervousness/restlessness
- Hyperactivity/irritability
- Palpitations/angina
- Muscle cramps
- Polyuria
- Diarrhea
- Heat intolerance and sweating
- Oligomenorrhea
What are the signs of thyrotoxicosis?
- Thin body habitus
- Agitation/restlessness
- Tachycardia
- AFib
- Muscle weakness, hyperreflexia, osteoporosis, fine resting tremors
- Goiter/thyromegaly
- Warm, moist skin
- Lid lag or lid retraction
What are the specific manifestations of Graves Disease?
- Graves Ophthalmology
- Thyroid acropachy
- Graves dermopathy
What does Graves Ophthalmology look like?
- Upper eyelid retraction
- Lid lag with downward gaze
- “Staring” appearance
- Conjunctival edema
What does thyroid acropachy look like?
- Digital clubbing
- Swelling of fingers and toes
- Periosteal reaction of extremity bones
What does Graves dermopathy/pretibial myxedema look like?
- Erythematous, rough plaques
- Lymphoid infiltration
What kind of cardiopulmonary manifestations can occur in Graves Disease?
- Forceful heartbeats
- Exertional dyspnea
- Abnormal conduction
- Cardiomyopathy
In what trimester of pregnancy is Graves Disease most common?
2nd trimester
Clinical
Why does Graves Disease see an improvement throughout pregnancy?
Physiologic suppression of the immune system.
Clinical
Divya is a 37-year-old female who was just diagnosed with primary hyperthyroidism. Assume she has not received any clinical interventions to treat her hormone status.
● What would we expect to happen to her T4 level?
● What would we expect to happen to her T3 level?
● What would we expect to happen to her TSH level?
● What would we expect to happen to her TRH level?
- T4 = elevated
- T3 = elevated
- TSH = decreased
- TRH = decreased
What lab abnormalities might we see in a primary hyperthyroidism patient?
- Hypercalcemia
- Elevated Alk phosphatase
- Anemic
- Decreased granulocytes
What lab is typically higher in thyroiditis over Graves Disease?
ESR
Low levels of what might suggest Thyrotoxicosis factitia?
Low serum thyroglobulin levels.
What imaging test might help us differentiate thyrotoxicosis etiologies?
Radioactive iodine uptake (RAI).
If I see increased uptake of iodine in an RAI test, what are the more likely etiologies?
- Graves Disease
- Toxic solitary nodule
- Toxic multinodular goiter
- Type 1 amiodarone thyrotoxicosis
If I see decreased uptake of iodine in an RAI test, what are the more likely etiologies?
- Thyroiditis
- Iodine-induced thyrotoxicosis
- Type 2 amiodarone thyrotoxicosis
What kind of person should almost never get an RAI test?
Pregnant women, since it contains radiation.
What are the limitations of a thyroid US?
- Cannot tell benign from malignant
- Cannot measure metabolic activity
- Depends on operator and body habitus
If a Graves patient has severe ophthalmologic manifestations, what is the typical treatment?
- Steroid therapy
- Severe: radiation or surgery
What is hypokalemic periodic paralysis and who is it MC in?
- Symmetric flaccid paralysis after IV dextrose, oral carbs of vigorous exercise.
- Asian or american indian men.
What is a thyroid storm? Manifestations?
Severe, life-threatening thyrotoxicosis
* Marked delirium
* Severe tachycardia
* Vomiting and diarrhea
* Dehydration
* Very high fever
What is the treatment protocol for a thyroid storm?
- Thiourea drug: methimazole or PTU (inhibits iodine oxidation, preventing formation of thyroid hormone.)
- Iodinated contrast agent: ipodate sodium or iopanoic acid (Inhibits peripheral conversion of T4 to T3)
- BB: propranolol or atenolol (symptomatic relief)
- Hydrocortisone
- AVOID ASA
What is the definitive treatment for a thyroid storm?
- Radioactive iodine
- Surgery
What lab values correspond to subclinical hyperthyroidism?
- Normal serum FT4 and T3
- Low TSH
Clinical
Excess ingestion of which food product can cause hyperthyroidism?
● Red meat
● Chamomile tea
● Kelp supplements
● Omega-3 fatty acids
KELP
Clinical
While useful to evaluate thyroid disease, thyroid ultrasonography is limited in that it cannot…
● Assess metabolic activity of a thyroid mass
● Distinguish a solid mass from a cystic mass
● Assess blood flow to the thyroid gland
● Evaluate smooth versus poorly defined mass margins
Assessing metabolic activity of a thyroid mass.
Clinical
Untreated hyperthyroidism could eventually lead to all of the following complications, except…
● Osteoporosis
● Peripheral edema
● Edema
● Evaluate smooth versus poorly defined mass margins
- Peripheral edema
- Edema
What medications do we give for Graves Disease patients?
- BBs (symptomatic relief until other therapy kicks in.)
- Iodinated contrast agents (severely symptomatic patients, but efficacy wanes over time)
- Thiourea drugs (Inhibits thyroid hormone production without damaging thyroid.)
What are the two thiourea drugs? When is one preferred over the other?
- Methimazole: Most patients
- Propylthiouracil (PTU): first trimester or breast feeding)
Pregnant titties being used = PTU preferred
What is the main SE of methimazole that makes it dangerous to use in pregnancy?
Teratogenicity risk and goes into breast milk.
What are the 2 MOAs of PTU?
- Inhibits organification of iodine, preventing formation of thyroid hormone.
- Decreases peripheral conversion of T4 to T3.
What is the BBW of PTU?
Hepatotoxicity
Clinical
Which of the following tests would be helpful when choosing whether to put a patient on methimazole or PTU?
● A urine hCG (pregnancy) test
● A comprehensive metabolic panel (CMP)
● A complete blood count (CBC)
● All of the above
All of the above
When do we use radioactive iodine for Graves Disease? When do we use surgery instead?
- RAI is not safe for pregnancy for lactation.
- Surgery is for those who are pregnant, refuse radiation, or are suspicious for malignancy.
Why is RAI more ideal for Graves Disease treatment?
No risk of damaging the recurrent laryngeal nerve or causing hypoparathyroidism.
What are the treatment options for a toxic solitary nodule causing thyrotoxicosis?
- Symptomatic: BB + PTU or methimazole
- Surgery: pt < 40 or healthy older pt.
- RAI: if not surgical candidate
What are the treatment options for amiodarone-induced thyrotoxicosis?
- Symptomatic: BB + methimazole
- D/C Amiodarone
- Surgery for refractory cases
What are the treatment options for a toxic multinodular goiter?
- Symptomatic: BB + Thiourea drug
- Surgery or RAI