Endocrinology Practice Questions

Correct Answer: A

Rationale: Rationale: A: Correct. Cushing's disease is caused by a pituitary adenoma secreting excess ACTH, stimulating adrenal cortex to produce excess cortisol. B: Incorrect. Cushing's disease does not result from excess cortisol secretion by the pituitary adenoma. C: Incorrect. Cushing's disease is not caused by an adrenal adenoma secreting excess ACTH. D: Incorrect. Cushing's disease is not caused by an adrenal adenoma secreting excess cortisol. Summary: The correct answer is A because it accurately describes the pathophysiology of Cushing's disease, where a pituitary adenoma secretes excess ACTH leading to increased cortisol production. Choices B, C, and D are incorrect as they misinterpret the primary source of hormone overproduction in Cushing's disease.

Correct Answer: B

Rationale: The correct answer is B: Intranasal vasopressin may be helpful. In diabetes insipidus, there is a deficiency of vasopressin leading to excessive urination and thirst. Administering vasopressin intranasally can help replace the deficient hormone, reducing urine output and thirst. Hypernatremia (choice A) can occur due to excessive water loss, but it is not always present. There is no osmolar gap (choice C) in diabetes insipidus. Urine specific gravity (choice D) is typically low in diabetes insipidus due to the dilute urine produced.

Correct Answer: C

Rationale: The correct answer is C: Stress. Stress triggers the release of growth hormone through the activation of the hypothalamic-pituitary-adrenal axis. When the body is under stress, the hypothalamus signals the pituitary gland to release growth hormone. This hormone then stimulates growth and cell reproduction. Glucocorticoids (A) and somatostatin (B) actually inhibit the release of growth hormone. Obesity (D) can lead to decreased growth hormone release due to disrupted hormonal regulation. In summary, stress is the correct answer as it directly stimulates the release of growth hormone, while the other choices inhibit or have a negative impact on growth hormone release.

Correct Answer: D

Rationale: The correct answer is D because oxytocin and anti-diuretic hormone are synthesized in the hypothalamus and stored in the posterior pituitary gland before being released into the bloodstream. This process is essential for regulating various physiological functions. Choices A and C are incorrect as oxytocin and anti-diuretic hormone are not complex steroids and are not released from the anterior pituitary. Choice B is also incorrect because while these hormones are indeed synthesized in the posterior pituitary, they are stored in the posterior pituitary before their release.

Correct Answer: B

Rationale: The correct answer is B: Weight loss. Hypothyroidism is characterized by an underactive thyroid gland, leading to a decreased metabolic rate. This typically results in weight gain, not weight loss. Choices A, C, and D are all associated with hypothyroidism. Loss of libido can occur due to hormonal imbalances, cardiac failure can result from the decreased metabolic rate affecting the heart, and organic psychosis can be a symptom of severe untreated hypothyroidism.