Mod 1 lecture 2: thyroid disease

Question 1

what drugs are used to help hypothyroidism

Answer 1

T4-levothyroxine (synthroid)
T3- Liothyronine (cytomel)
T3 + T4 (Liotrix)

Question 2

what drugs are used for hyperthyroidism

Answer 2

Methimazole
propylthiouracil (PTU)
propranolol
iodine and potassium iodide

Question 3

what are the signs/symptoms of hypothyroidism

Answer 3

anorexia
fatigue, depression, lethargy
cold intolerance
constipation
dry skin, coarse hair
anemia
muscle stiffness and/or cramps
memory impairment
bradycardia
hypoflexia
enlarged thyroid

Question 4

what are the goals of treatment for hypothyroidism

Answer 4

resolution of sings and symptoms
achieve normalization of serum thyrotropin (TSH) with improvement in thyroid hormone concentrations
avoid over treatment especially in the elderly

Question 5

What is T4-levothyroxine

Answer 5

synthetic T4
deiodinated in patients tissues
half life of 7 days - dosed qd
metabolized in the liver
eliminated in bile
toxicity associated with increased levels of T4 - hyperthyroidism

Question 6

What is T3- liothyronin (cytomel)

Answer 6

synthetic T3
rapid oral absorption (may cause transient hyperthyroidism)
short half life
metabolized in liver and eliminated in bile
toxicity - increased risk of cardiotoxicity
rare indication for use of T3 alone

Question 7

what is T3+T4 (liotrix)

Answer 7

developed to try to mimic normal, physiological hormone levels
benefit/efficacy has not been demonstrated - not used routinely

Question 8

what are the signs and symptoms of hyperthyroidism

Answer 8

nervousness
tremor
heat intolerance
sweating
increased appetite, weight loss
loose stools
irritability, anxiety, insomnia
fatigue
muscle weakness
tachycardia, afib, palpitations, PACs
hyperreflexia

Question 9

What are the thioamides

Answer 9

Propylthiouracil (PTU) and Methimazole

Question 10

what is Propylthiouracil (PTU)

Answer 10

inhibits thyroid hormone synthesis and D1 (iodothyronin deiodinase)
half life 60-75 minutes
toxicity: teratogenic, hepatotoxicity and bone marrow suppression

Question 11

what is methimazole

Answer 11

inhibits thyroid hormone synthesis and does NOT affect D1
half life of 4-6 hours
toxicity: teratogenic (preferred in 2nd/3rd trimester), hepatotoxic and bone marrow suppression

Question 12

what is propranolol

Answer 12

non-selective beta-blocker
symptomatic control in thyroid storm - blocks B1, B2 receptor equally and decreases CO
inhibits deiodination of T4 - reduces circulating T3 (small effect)
administered IV in emergent setting

Question 13

what is Iodine and KI

Answer 13

iodine: inhibition of biosynthesis (iodination of tyrosine) and inhibition of secretion (release of T3/T4)
effects on serum thyroid hormone are maximal at 10 days but transient

Question 14

what are the AE of iodine and KI

Answer 14

exacerbation of hyperthyroidism
mucosal injury: mouth, pharynx, esophageal or duodenal lesions

Question 15

what is potassium iodide

Answer 15

medication and dietary supplement (in low I areas)
used to treat severe hyperthyroidism and to protect the thyroid gland when using radiopharmaceuticals

Question 16

what are the indications for potassium iodide

Answer 16

preoperative preparation of thyroidectomy in graves disease to decrease gland vascularity
thyroid storm - b/c iodine blocks release of T3 and T4 from gland within hours
in combined tx with anti-thyroid drugs to improve short-term control of Graves hyperthyroidism
after admision of radioiodine in graves disease

Question 17

what is radioactive iodine

Answer 17

administered orally as sodium iodide in a solution or capsule
rapidly absorbed into thyroid gland, causing local tissue destruction (renders thyroid inactive over 6-18 weeks)

Question 18

what are the indications for radioactive iodine

Answer 18

graves disease
toxic adenoma
multinodular goiter