In primary aldosteronism, what are the expected laboratory findings?

• A. Hypertension with hypokalemia and metabolic alkalosis; low renin (renin suppressed).
• B. Hypotension with hyperkalemia and metabolic acidosis; high renin.
• C. Hypertension with hyperkalemia and metabolic acidosis; normal renin.
• D. Hypotension with hyponatremia and metabolic alkalosis; high renin.

Answer: (A)

Excess aldosterone drives sodium retention and volume expansion, which raises blood pressure. At the same time, it increases potassium and hydrogen ion loss in the distal nephron, producing hypokalemia and metabolic alkalosis. Because the circulating aldosterone is high and the blood pressure is also elevated, the kidneys decrease renin release, so renin levels are suppressed. This combination—hypertension with low renin and hypokalemia with metabolic alkalosis—is the hallmark pattern, and it explains why the aldosterone-to-renin ratio is typically elevated in primary aldosteronism.