In Addison's disease, which laboratory findings would most support the diagnosis?

• A. Hyperkalemia, hyponatremia, and hypoglycemia.
• B. Hypertension, hypernatremia, and hypokalemia.
• C. Hypercalcemia, hyperglycemia, and polycythemia.
• D. Hypokalemia, hypernatremia, and tachycardia.

Answer: (A)

Addison's disease causes a deficiency of adrenal hormones, especially aldosterone and cortisol. Without aldosterone, the kidneys waste sodium and water, leading to low sodium (hyponatremia) and volume depletion; they also excrete less potassium, causing high potassium (hyperkalemia). Cortisol deficiency impairs gluconeogenesis, making hypoglycemia more likely, especially if there’s limited food intake or illness. This combination—hyperkalemia, hyponatremia, and hypoglycemia—fits Addison’s adrenal insufficiency best because it reflects both the mineralocorticoid and glucocorticoid deficits.

The other patterns don’t match Addison’s. Hypertension with hypernatremia and hypokalemia suggests excess mineralocorticoid effects or other conditions, not primary adrenal failure. Hypercalcemia, hyperglycemia, and polycythemia aren’t typical findings for Addison’s. Hypokalemia with hypernatremia and tachycardia also doesn’t align with the hormonal losses seen in primary adrenal insufficiency.