Correct Answer: C

Rationale: The correct answer is C because dipsogenic diabetes insipidus is caused by a defect or damage to the hypothalamus, not the pituitary gland or pituitary stalk. The hypothalamus regulates thirst and water intake, so damage to this area can lead to excessive thirst and dilute urine output characteristic of diabetes insipidus. Choices A and D incorrectly attribute the cause to the pituitary gland or pituitary stalk, which are not directly involved in regulating thirst. Choice B is incorrect as it mentions malfunction of the hunger mechanism, which is not relevant to dipsogenic diabetes insipidus. Thus, choice C is the most accurate definition based on the pathophysiology of the condition.

Correct Answer: A

Rationale: The correct answer is A. Visual changes such as double vision, reduced vision, tunnel vision are common symptoms of acromegaly due to the enlargement of tissues in the eye sockets affecting the optic nerve. Paresthesia and weakness in the hands (B) are not typical symptoms of acromegaly but may be seen in conditions affecting the peripheral nerves. Diarrhoea (C) and abdominal distention (D) are not associated with acromegaly but may be seen in gastrointestinal disorders.

Correct Answer: A

Rationale: The correct answer is A: Adrenaline. In injury to the adrenal cortex, adrenaline is least affected because it is primarily synthesized and secreted by the adrenal medulla, not the adrenal cortex. Cortisol, aldosterone, and androstenedione are hormones produced by the adrenal cortex. In adrenal cortex injury, the secretion of cortisol, aldosterone, and androstenedione would be significantly affected due to the damage to the adrenal cortex, leading to hormonal imbalance and related symptoms. Therefore, option A is the correct answer as it is not primarily secreted by the adrenal cortex and would be least affected in this scenario.

Correct Answer: B

Rationale: The correct answer is B: Chronic pancreatitis. Hypoglycemia is not typically associated with chronic pancreatitis as it is more related to pancreatic insufficiency and impaired glucose regulation. A: Glycogen storage disease can lead to hypoglycemia due to the inability to properly release stored glucose. C: Galactosaemia can cause hypoglycemia due to the impaired breakdown of galactose into glucose. D: Post-gastrectomy can lead to hypoglycemia due to rapid glucose absorption and altered hormonal responses.

Correct Answer: A

Rationale: The correct answer is A because Klinefelter's syndrome is characterized by small, soft testes due to the presence of an extra X chromosome (47, XXY). This leads to hypogonadism and inadequate testosterone production, resulting in underdeveloped testes. Choice B (46, XO) is incorrect as it refers to Turner syndrome. Choice C (upper segment> lower segment) is unrelated to Klinefelter's syndrome. Choice D (Gynaecomastia) is a symptom of Klinefelter's syndrome but not the defining characteristic.