Which of the following is a trigger for the onset of Graves' disease?

Correct Answer: C

Rationale: The correct answer is C: Stressful life events. Graves' disease is an autoimmune disorder where the immune system mistakenly attacks the thyroid gland, causing it to produce excess thyroid hormone. Stressful life events can trigger or exacerbate autoimmune conditions like Graves' disease by impacting the immune system's functioning. Trauma, iodine deficiency, and bacterial infection are not direct triggers for Graves' disease. Trauma can cause thyroid issues but not specifically Graves' disease. Iodine deficiency can lead to goiter but is not a direct trigger for Graves' disease. Bacterial infections can cause thyroiditis but are not a common trigger for Graves' disease.

Correct Answer: A

Rationale: The correct answer is A: Autoimmune Mediated. In this case, the patient is presenting with symptoms of hyperthyroidism along with a goiter, which is indicative of Graves' disease, an autoimmune disorder where antibodies stimulate the thyroid gland to produce excess thyroid hormones. The presence of increased iodine uptake in the thyroid scan supports this diagnosis. On the other hand, immune complex mediated diseases typically involve tissue damage caused by immune complexes, not thyroid hormone excess. The cause being unknown or infection-related are not consistent with the symptoms and thyroid scan findings in this case.

Correct Answer: A

Rationale: The correct answer is A: 17α-hydroxylase. In this scenario, the patient presents with hypertension, high aldosterone, and low cortisol levels. This pattern suggests a defect in the enzyme 17α-hydroxylase, which is responsible for both cortisol and aldosterone synthesis. Glucocorticoid treatment lowers aldosterone levels and subsequently normalizes blood pressure. The other choices (B: 21β-hydroxylase, C: 3β-hydroxysteroid dehydrogenase, D: aldosterone synthase) are not implicated in this specific presentation and do not align with the observed hormone levels and response to glucocorticoid therapy.

Correct Answer: B

Rationale: Step 1: Antidiuretic hormone (ADH) is released by the posterior pituitary, and its main function is to increase water reabsorption in the kidneys, leading to decreased urine volume and increased blood volume. Step 2: If ADH causes urine volume to increase and blood volume to decrease, it would be counterproductive to its known physiological role. Step 3: Therefore, Choice B is false as it contradicts the established function of ADH. Summary: - Choice A is true because oxytocin and antidiuretic hormone are indeed produced in the hypothalamus and stored in the posterior pituitary. - Choice C is true as luteinizing hormone does trigger ovulation and stimulates the production of progesterone and some estrogens. - Choice D is true because hyposecretion of follicle-stimulating hormone or luteinizing hormone can lead to infertility in both males and females.

Correct Answer: A

Rationale: The correct answer is A: somatotropin. The growth hormone produced by the pituitary gland is known as somatotropin. - "Somato" refers to the body, indicating its role in regulating body growth. - "Tropin" refers to stimulation, emphasizing its function in promoting cell growth and regeneration. - Prolactin (B) is responsible for milk production. - Luteinizing hormone (C) and follicle-stimulating hormone (D) are involved in reproductive functions, not growth regulation.