Correct Answer: B

Rationale: ADH (antidiuretic hormone), also known as vasopressin, is secreted by the posterior lobe of the pituitary gland. ADH plays a key role in regulating water balance in the body by controlling the reabsorption of water in the kidneys. When the body senses a decrease in blood volume or an increase in blood osmolarity, ADH is released to signal the kidneys to conserve water, leading to concentrated urine production and water retention in the body.

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.

Correct Answer: D

Rationale: An Addisonian crisis, also known as an acute adrenal crisis, is a life-threatening medical emergency that occurs due to severe adrenal insufficiency, leading to a sudden drop in cortisol levels. Cortisol is a vital hormone produced by the adrenal glands, and its deficiency can result in serious symptoms such as hypotension, dehydration, electrolyte imbalances, and shock. If left untreated, an Addisonian crisis can be fatal. Therefore, the correct description of an Addisonian crisis is severe adrenal insufficiency resulting in dangerously low serum cortisol levels.

Correct Answer: A

Rationale: Primary hyperparathyroidism is a condition characterized by the overproduction of parathyroid hormone (PTH) by the parathyroid glands, leading to elevated levels of calcium in the blood. This excessive calcium can cause calcification in various tissues, including the basal ganglia of the brain. The calcification of the basal ganglia in primary hyperparathyroidism is a well-known radiological finding and can be visualized on imaging studies such as CT scans or MRI. Hypoparathyroidism, on the other hand, is characterized by low levels of PTH and results in decreased serum calcium levels, making it an unlikely cause of basal ganglia calcification. Secondary hyperparathyroidism is associated with chronic kidney disease and is also characterized by high PTH levels, but basal ganglia calcification is not a typical manifestation of this condition. Milk-alkali syndrome is a disorder characterized by excessive intake of

Correct Answer: A

Rationale: Thyrotoxicosis typically presents with hypermetabolism and various neuromuscular manifestations. Myasthenic syndrome, which involves muscle weakness and fatigability, is not a common neuromuscular feature of thyrotoxicosis. Instead, manifestations such as brisk knee jerk reflexes, hypokalaemic periodic paralysis (due to shifts in potassium levels), and hyperkinesia (excessive movement) are more commonly observed in patients with thyrotoxicosis. Myasthenic syndrome is more commonly associated with autoimmune disorders affecting the neuromuscular junction, such as myasthenia gravis.