Endocrinology Exam Questions

Correct Answer: A

Rationale: In the syndrome of inappropriate antidiuretic hormone (SIADH), there is excessive secretion of antidiuretic hormone (ADH) leading to increased water reabsorption in the kidney tubules. This results in dilutional hyponatremia because the amount of water reabsorbed is greater than the electrolytes, such as sodium, leading to a relative decrease in their concentration in the blood. As a result, hyponatremia occurs in SIADH, contributing to symptoms such as nausea, confusion, and seizures due to the imbalance in electrolytes.

Correct Answer: A

Rationale: Pseudo-Cushing's syndrome is a condition that mimics the symptoms of Cushing's syndrome but is not actually caused by excess cortisol production by the adrenal glands. It can be caused by various conditions such as chronic alcoholism, obesity, depression, and certain medications. However, myxoedema (also known as severe hypothyroidism) is not typically associated with pseudo-Cushing's syndrome. Myxoedema is characterized by low thyroid hormone levels, which would not lead to the symptoms of pseudo-Cushing's syndrome.

Correct Answer: A

Rationale: The most common cause of Addison's disease is autoimmune adrenalitis, also known as autoimmune adrenal insufficiency. In autoimmune adrenalitis, the adrenal glands are damaged by immune system-mediated processes, leading to their dysfunction. This autoimmune destruction typically presents as bilateral adrenal cortex atrophy due to the formation of granulomas. Therefore, the commonest cause of Addison's disease is the presence of granulomas in the adrenal glands, making option A, Granuloma, the correct choice.

Correct Answer: C

Rationale: Hormones are chemical messengers that are produced by various glands in the body and released into the bloodstream to signal and regulate the activity of specific target cells. Unlike energy sources that can be metabolized for energy production (like carbohydrates and fats), hormones are not typically used as an energy source themselves (Choice B). Hormones are typically not biologically inert by themselves (Choice A), as they have specific functions in regulating various physiological processes in the body. While some hormones may be stored in secretory granules before release, not all hormones are stored in this manner (Choice D). Additionally, hormones are not always released by exocytosis (Choice E), as some hormones can also be released through other mechanisms such as diffusion. The correct choice, therefore, is C: hormones are incorporated as a structural moiety into another molecule, as they bind to specific receptors on target cells to elicit a cellular response and regulate physiological functions.

Correct Answer: D

Rationale: Growth hormone is primarily released during sleep, particularly during the first few hours of deep sleep. This release is pulsatile in nature, with the majority occurring at night. Growth hormone plays a critical role in growth, repair, and development of body tissues during periods of rest and sleep. Additionally, the secretion of growth hormone is also influenced by factors such as stress, exercise, and nutritional status.