A 70-year-old woman presents with fatigue, anorexia, and weight loss. She has noticed darkening of her skin, particularly in sun-exposed areas. Laboratory tests reveal hyponatremia, hyperkalemia, and low cortisol levels. What is the most likely diagnosis?

Correct Answer: B

Rationale: The most likely diagnosis for the 70-year-old woman is Addison's disease. The symptoms of fatigue, anorexia, weight loss, darkened skin, along with hyponatremia, hyperkalemia, and low cortisol levels indicate adrenal insufficiency. Addison's disease is characterized by inadequate production of cortisol and aldosterone by the adrenal glands. The darkening of the skin, known as hyperpigmentation, is a classic sign of Addison's due to increased ACTH levels stimulating melanin production. In contrast, Cushing's syndrome presents with weight gain, hypertension, and high cortisol levels. Hypothyroidism typically presents with weight gain, cold intolerance, and constipation. Pheochromocytoma presents with hypertension, palpitations, and headaches due to excess catecholamine production. Therefore, the correct diagnosis in this case is Addison's disease.

Correct Answer: B

Rationale: The correct answer is B: Hyperthyroidism. In this case, the low TSH and high free T4 levels indicate an overactive thyroid gland, leading to symptoms like fatigue, weight gain, and constipation. The low TSH is due to negative feedback as the high free T4 suppresses TSH production. Hyperthyroidism fits this clinical picture, as opposed to hypothyroidism (choice A) which would have high TSH and low free T4 levels. Thyroiditis (choice C) typically presents with symptoms of both hyperthyroidism and hypothyroidism and is usually transient. Thyroid cancer (choice D) is less likely given the presentation of symptoms and specific lab results.

Correct Answer: C

Rationale: The most likely diagnosis is Crohn's disease (Choice C). This is supported by the symptoms of abdominal pain, diarrhea, weight loss, mouth ulcers, and perianal fistula, which are characteristic of Crohn's disease. These symptoms are not typically seen in irritable bowel syndrome (Choice B) or diverticulitis (Choice D). While ulcerative colitis (Choice A) may also present with similar symptoms, the presence of perianal fistula and mouth ulcers is more indicative of Crohn's disease. Crohn's disease is a chronic inflammatory condition that can affect any part of the gastrointestinal tract, leading to the diverse range of symptoms seen in this patient.

Correct Answer: D

Rationale: The correct answer is D: Place the tablet under your tongue. Nitroglycerin is a vasodilator used to relieve chest pain in patients with MI. Placing the tablet under the tongue allows for rapid absorption through the oral mucosa, providing quick relief. Taking it with food (A) may delay absorption. Swallowing the tablet whole (B) would result in slower absorption through the GI tract. Taking it at bedtime (C) is not necessary for immediate relief of chest pain.

Correct Answer: C

Rationale: The correct answer is C, engaging in at least 150 minutes of moderate exercise per week. Regular exercise helps lower blood pressure by strengthening the heart, improving blood flow, and reducing stress. It also helps with weight management, which is crucial for hypertension. Choice A is incorrect because saturated fats can increase the risk of heart disease and worsen hypertension. Choice B is incorrect because excessive alcohol intake can raise blood pressure. Choice D is incorrect because excessive salt intake can lead to high blood pressure. Overall, regular exercise is a key lifestyle modification for managing hypertension.