The corticosteroid preferred for replacement therapy in Addison's disease is:

Correct Answer: B

Rationale: The correct answer is B: Fludrocortisone. In Addison's disease, the adrenal glands do not produce enough cortisol and aldosterone. Fludrocortisone is a synthetic steroid that mimics aldosterone, helping to maintain electrolyte balance. It is preferred over aldosterone itself due to better pharmacokinetics and longer duration of action. Hydrocortisone (C) is used to replace cortisol. Betamethasone (D) is a potent glucocorticoid with no mineralocorticoid activity. Aldosterone (A) is not the preferred corticosteroid for replacement therapy in Addison's disease.

Correct Answer: B

Rationale: The correct answer is B: Hypertrophy of interstitial cells of testes. Testosterone therapy can lead to an increase in testosterone levels, causing hypertrophy of interstitial cells, which produce testosterone. Choice A is incorrect as seminiferous tubules are not affected by testosterone therapy. Choice C is also incorrect as atrophy of interstitial cells is not a known effect of testosterone therapy. Choice D is incorrect as only choice B accurately reflects the impact of prolonged testosterone therapy on testicular cells.

Correct Answer: D

Rationale: The correct answer is D: Precocious puberty. Parenteral testosterone therapy can suppress endogenous testosterone production, delaying puberty rather than causing precocious puberty. Gynaecomastia (A), acne (B), and cholestatic jaundice (C) are possible adverse effects of testosterone therapy due to its impact on hormone levels and liver function. However, precocious puberty is not a known side effect of testosterone therapy in boys.

Correct Answer: D

Rationale: The correct answer is D: Hot flashes. Danazol is a synthetic androgen that suppresses ovarian function, leading to amenorrhea and decreased estrogen levels. This mechanism of action makes it unlikely to cause hot flashes, which are commonly associated with estrogen fluctuations. Acne (Choice A), menorrhagia (Choice B), and amenorrhea (Choice C) are potential side effects of Danazol due to its hormonal effects on the body.

Correct Answer: A

Rationale: The correct answer is A: Danazol. Danazol is a synthetic androgen that suppresses gonadotropin secretion, leading to elevated testosterone levels. Finasteride inhibits 5-alpha-reductase, reducing dihydrotestosterone levels. Flutamide is an androgen receptor antagonist, lowering testosterone levels. Ketoconazole inhibits steroid synthesis, decreasing testosterone production. Therefore, only Danazol directly increases circulating testosterone levels in men.