Inhibition of which of the following enzymes most likely mediated the therapeutic effect of the drug in the patient's disease?

Correct Answer: D

Rationale: The correct answer is D: Stimulation of thyroid peroxidase. In the patient's disease, a drug would likely be used to increase thyroid hormone production. Thyroid peroxidase plays a crucial role in thyroid hormone synthesis by catalyzing the iodination of tyrosine residues on thyroglobulin. By stimulating thyroid peroxidase activity, the drug can enhance thyroid hormone production. The other choices (A, B, C) are incorrect because inhibiting thyroid protease, topoisomerase I, or proteolysis of thyroglobulin would not directly impact thyroid hormone synthesis and, therefore, would not likely mediate the therapeutic effect in the patient's disease.

Correct Answer: D

Rationale: The correct answer is D. Therapy typically suppresses the immune system, leading to a decrease in lymphocytes. Lymphocytes are a key component of the immune system, so a decrease is expected with therapy. Neutrophils are primary defenders against infections, so they would not decrease. Erythrocytes are red blood cells responsible for oxygen transport and their decrease would lead to anemia, not a typical therapy response. Basophils are involved in allergic reactions and inflammation, so an increase in basophils would not be a typical response to therapy.

Correct Answer: B

Rationale: The correct answer is B: Fludrocortisone excess. In Addison's disease, there is adrenal insufficiency leading to low levels of cortisol and aldosterone. Fludrocortisone is a synthetic mineralocorticoid used to replace aldosterone in the treatment of Addison's disease. Excess fludrocortisone can cause retention of sodium and water, leading to hypertension, hypokalemia, weakness, and paresthesias. Constipation can also occur due to altered electrolyte balance. A: Cortisol-induced hyperglycemia is not the best explanation for the patient's symptoms as hyperglycemia is not a prominent feature of Addison's disease. C: Inadequate therapy of adrenal insufficiency would not cause the specific symptoms mentioned. D: Cortisol-induced myopathy is not the primary cause of weakness and paresthesias in Addison's disease; aldosterone deficiency leading to electrolyte imbalance is more relevant.

Correct Answer: C

Rationale: The correct answer is C: Finasteride. Finasteride is a 5-alpha reductase inhibitor that can decrease the size of uterine fibroids by inhibiting the conversion of testosterone to dihydrotestosterone. This can help reduce symptoms such as heavy menstrual bleeding and pelvic pain before surgery. Ethinyl estradiol (A) is a form of estrogen and can potentially worsen fibroid symptoms. Flutamide (B) is an antiandrogen used for conditions like prostate cancer, not for uterine fibroids. Mifepristone (D) is a progesterone receptor antagonist used for medical abortion, not for managing fibroid symptoms before surgery.

Correct Answer: B

Rationale: The correct answer is B: Oxandrolone. Oxandrolone is an anabolic steroid known to cause hyperpigmentation due to increased melanin production. The patient's history of taking oxandrolone aligns with the presentation of hyperpigmentation on her face. Ethinyl estradiol (choice A) is a common component of hormonal contraceptives but is not known to cause hyperpigmentation. Erythropoietin (choice C) is a hormone used to stimulate red blood cell production and is not associated with hyperpigmentation. Norethindrone (choice D) is another hormonal contraceptive component that does not typically cause hyperpigmentation. In this case, the patient's use of oxandrolone is the most likely culprit for her hyperpigmentation.