**Question:** In Addison's disease drug to be given is

A. Hydrocortisone
B. Fludrocortisone
C. Desmopressin
D. Thyroxine

**Core Concept:** Addison's disease is a disorder characterized by the deficiency of adrenal corticosteroids, particularly cortisol. The primary treatment involves replacing the deficient hormones, specifically cortisol and aldosterone.

**Why the Correct Answer is Right:** In Addison's disease, the adrenal glands are damaged, leading to a decrease in cortisol production. Hydrocortisone, a synthetic corticosteroid, is used as a replacement for cortisol, which helps to alleviate symptoms and maintain homeostasis.

**Why Each Wrong Option is Incorrect:**

A. Fludrocortisone: This is a synthetic mineralocorticoid used to replace aldosterone deficiency in Addison's disease. However, it does not address cortisol deficiency, which is the primary concern in this scenario.
B. Fludrocortisone is incorrect because it is a mineralocorticoid, not cortisol. Fludrocortisone compensates for the aldosterone deficiency in Addison's disease, but it does not address cortisol deficiency.
C. Desmopressin: This drug is used for treating low levels of antidiuretic hormone (ADH), which is unrelated to cortisol or aldosterone deficiency in Addison's disease.
D. Thyroxine: This is a thyroid hormone, not a corticosteroid or mineralocorticoid, so it is irrelevant in treating cortisol and aldosterone deficiency in Addison's disease.

**Brief Explanation of Addison's Disease:** Addison's disease (primary adrenal insufficiency) occurs when the adrenal glands are unable to produce sufficient amounts of cortisol and aldosterone. The appropriate treatment focuses on replacing these deficient hormones to restore physiological balance and alleviate symptoms. In this case, hydrocortisone is the correct choice as it replaces cortisol, which is the primary concern in Addison's disease.

**Clinical Pearl:** In clinical practice, it is essential to differentiate between primary adrenal insufficiency (Addison's disease) and secondary adrenal insufficiency (hypothalamic-pituitary dysfunction) since treatment varies for each. Addison's disease typically involves cortisol replacement, while in secondary adrenal insufficiency, hydrocortisone is less appropriate because it is a synthetic cortisol analog and may exacerbate the underlying pituitary problem. Instead, a mineralocorticoid like fludrocortisone is more suitable for addressing aldosterone deficiency in secondary adrenal insufficiency.

**Core Concept:** Hydrocortisone is a synthetic cortisol analog that can replace cortisol and alleviate symptoms in patients with Addison's disease, a primary adrenal insufficiency. In this context, hydrocortisone is the appropriate medication to address cortisol deficiency.