Which of the following disorders most likely caused the patient's tachycardia?

Correct Answer: B

Rationale: The correct answer is B: Atrial fibrillation. Atrial fibrillation is a common arrhythmia characterized by rapid, irregular heartbeats that can lead to tachycardia. In atrial fibrillation, the atria quiver instead of contracting effectively, leading to an irregular heart rhythm and increased heart rate. This condition can cause tachycardia due to the ineffective pumping of blood by the heart. Incorrect choices: A: Hypertrophic cardiomyopathy - This disorder can cause heart muscle thickening, leading to decreased ventricular filling and potentially causing arrhythmias, but it is not directly associated with tachycardia. C: Mitral regurgitation - This condition can lead to an enlarged left atrium and decreased cardiac output, but tachycardia is not a direct result of mitral regurgitation. D: Mitral stenosis - This condition can cause increased pressure in the left atrium and pulmonary congestion, but t

Correct Answer: B

Rationale: The correct answer is B: Prednisone. Prednisone is a corticosteroid commonly used to treat inflammatory conditions like autoimmune disorders. It suppresses the immune system, reducing inflammation and alleviating symptoms. The other choices (A, C, D) are unlikely to be the cause of the patient's signs and symptoms as they are not typically used to treat autoimmune disorders or related symptoms. Mifepristone is an abortion pill, fludrocortisone is a mineralocorticoid used for adrenal insufficiency, and methotrexate is a chemotherapy drug or used to treat autoimmune disorders like rheumatoid arthritis, but not typically for the symptoms described.

Correct Answer: A

Rationale: The correct answer is A: Increased catabolism of prostaglandins. Prednisone is a corticosteroid that exerts its therapeutic effect by suppressing the immune response and reducing inflammation. Prostaglandins are lipid compounds that promote inflammation. Prednisone works by inhibiting the production of prostaglandins, leading to decreased inflammation in Crohn's disease. Choice B: Decreased number of circulating neutrophils is incorrect because prednisone may decrease neutrophil count, but this is not the primary mechanism of action in treating Crohn's disease. Choice C: Increased proliferation of T cells is incorrect as prednisone actually suppresses T cell proliferation, which is beneficial in controlling inflammation in Crohn's disease. Choice D: Increased activation of complement system is incorrect as prednisone does not directly affect the complement system. The main mechanism of action lies in its ability to suppress inflammation by inhibiting prostaglandin synthesis.

Correct Answer: A

Rationale: Rationale: Anastrozole is an aromatase inhibitor used for hormone receptor-positive metastatic breast cancer. It inhibits estrogen synthesis, slowing cancer growth. Flutamide is for prostate cancer. Mifepristone is for abortion and Cushing's syndrome, not cancer. Ethinyl estradiol is a synthetic estrogen and not used for cancer.

Correct Answer: A

Rationale: The correct answer is A: Decreased body temperature. Medroxyprogesterone is a progestin that can suppress ovulation and reduce estrogen levels. Estrogen influences thermoregulation, so a decrease in estrogen levels can lead to a lower body temperature. The other choices are incorrect because B: increased estrogen secretion would be unlikely with progestin treatment, C: increased ventilatory response to carbon dioxide is not a typical effect of medroxyprogesterone, and D: decreased kidney excretion of sodium and water is not directly related to this medication.