Addison's disease is caused by which of the following?

• A. Over secretion of adrenal cortex
• B. Under secretion of adrenal cortex
• C. Underproduction of thyroid hormone
• D. Overproduction of cortisol

Answer: (B)

Addison's disease happens when the adrenal cortex makes too little cortisol and aldosterone. This primary adrenal insufficiency means both glucocorticoid and mineralocorticoid hormones are reduced, leading to symptoms like fatigue, weakness, low blood pressure, weight loss, and craving for salt. The lack of aldosterone also causes salt wasting, hyponatremia, and hyperkalemia, contributing to dehydration and hypotension. Because the pituitary can sense low cortisol, it ramps up ACTH, which in turn can cause hyperpigmentation in some cases due to ACTH-related melanocyte-stimulating activity.

Excess adrenal cortex activity would cause Cushing’s syndrome, not Addison’s. Underproduction of thyroid hormone points to hypothyroidism, a different endocrine issue. Overproduction of cortisol describes Cushing’s syndrome as well.