Which condition is characterized by hyponatremia and hyperkalemia?

• A. Graves' disease
• B. Addison's disease
• C. Hashimoto's thyroiditis
• D. Cushing's syndrome

Answer: (B)

This question tests how adrenal hormone deficiencies affect electrolyte balance. In Addison's disease, the adrenal cortex fails to produce enough aldosterone, the mineralocorticoid that signals kidneys to retain sodium and excrete potassium. When aldosterone is low, sodium loss in the urine leads to hyponatremia, and potassium isn’t excreted efficiently, leading to hyperkalemia. Cortisol deficiency can also contribute to hyponatremia through increased ADH, but the key pattern here is low aldosterone causing both low sodium and high potassium.

The other conditions involve different endocrine disturbances and don’t typically produce this same electrolyte picture. Graves' and Hashimoto's affect thyroid function and don’t produce the characteristic potassium-sodium changes. Cushing's syndrome involves excess cortisol and often presents with hypokalemia rather than hyperkalemia due to mineralocorticoid-like effects of cortisol.