Thioamides Drugs propylthiouracil (PTU) methimazole Mechanism inhibit thyroid hormone synthesis by blocking peroxidase-catalyzed reactions iodination of tyrosine residues of thyroglobulin coupling of DIT and MIT propylthiouracil ↓ peripheral conversion of T4 to T3 Clinical use HYPERthyroidism Toxicity skin rash agranulocytosis (rare) aplastic anemia hepatotoxicity (PTU) PTU not used first line in non-pregnant adults and children for this reason Pregnancy use PTU in the first trimester methimazole crosses the placenta and enters breast milk (may be teratogenic) Thyroid hormones Drugs levothyroxine synthetic T4 (thyroxine) triiodothyronine T3 Mechanism replaces endogenous thyroid hormones Clinical use HYPOthyroidism myxedema Toxicity thyrotoxicosis heat intolerance tachycardia dyspnea ↑ appetite tremors arrhythmias
QUESTIONS 1 of 4 1 2 3 4 Previous Next Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK (M1.EC.13.108) A 30-year-old female complains of heat intolerance, excessive sweating, and recent unintentional weight loss. She denies alcohol, tobacco, and other drug use and does not take any medications. Laboratory analysis reveals elevated serum T4 and decreased serum TSH. You elect to manage the patient’s condition pharmacologically with methimazole. Methimazole interferes with the function of which of the following proteins? QID: 100409 Type & Select Correct Answer 1 Thyroxine-binding globulin 7% (5/72) 2 Sex-hormone binding globulin 0% (0/72) 3 Thyroid peroxidase 78% (56/72) 4 5’-deiodinase 8% (6/72) 5 Sodium/iodide symporter 4% (3/72) M 1 Question Complexity C Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 3 Review Tested Concept Review Full Topic
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