Correct Answer: C

Rationale: Acromegaly is a disorder caused by excessive growth hormone production after the closure of the epiphyses (growth plates) in bones, leading to abnormal growth of tissues and organs. The following options are associated with acromegaly:

Correct Answer: B

Rationale: The triad of hyponatremia (low sodium levels in the blood), haemodilution (increased plasma volume), and urine hypertonic to plasma (high urine osmolality compared to blood osmolality) is characteristic of Syndrome of Inappropriate Antidiuretic Hormone (SIADH). In SIADH, there is excessive release of antidiuretic hormone (ADH), also known as vasopressin, leading to water retention by the kidneys and dilutional hyponatremia. This condition results in the body holding onto water, causing hyponatremia and dilution of the blood. The urine being hypertonic compared to plasma indicates that the kidneys are reabsorbing water effectively and concentrating the urine.

Correct Answer: C

Rationale: Cortisol secretion is directly stimulated by adrenocorticotropic hormone (ACTH), which is produced and released by the anterior pituitary gland in response to corticotropin-releasing hormone (CRH) from the hypothalamus. ACTH acts on the adrenal cortex to stimulate the production and release of cortisol. Aldosterone is another hormone produced by the adrenal cortex, but it is not directly involved in the stimulation of cortisol secretion. Prolactin is a hormone produced by the pituitary gland that plays a role in lactation, not cortisol secretion. High blood potassium levels can stimulate aldosterone secretion but do not directly stimulate cortisol secretion.

Correct Answer: D

Rationale: Persistent muscular weakness is characteristic of myxoedema, which is severe hypothyroidism. Myxoedema can lead to general weakness and fatigue, as thyroid hormones play a crucial role in controlling metabolism and energy production in the body. Other symptoms of myxoedema include cold intolerance, weight gain, dry skin, and hair loss. Conn's syndrome (hyperaldosteronism) is characterized by hypertension and low potassium levels, not persistent muscular weakness. Acromegaly is a condition resulting from excess growth hormone production, leading to enlarged body parts and metabolic changes but not specifically muscular weakness. Hyperparathyroidism is associated with high levels of parathyroid hormone, which can lead to bone weakening and calcium imbalance, but it is not typically a primary cause of muscular weakness.

Correct Answer: D

Rationale: Binding proteins are essential in transporting hormones through the bloodstream and protecting them from rapid degradation by enzymes. These proteins do not actually mediate the hormonal effects themselves. Hormonal effects are typically mediated by the hormone-receptor interactions at target cells. Binding proteins primarily serve as carriers for hormones and maintain their stability and availability in the circulation.