A 46-year-old female is being evaluated for a new-onset hypertension that was discovered on screening at her workplace. The patient had several readings revealing systolic and diastolic hypertension. Physical examination is normal. A complete laboratory evaluation was performed with unexplained hypokalemia as the only abnormality found. Which of the following is the most likely diagnosis for this patient?

• A. Pheochromocytoma
• B. Primary aldosteronism
• C. Renal artery stenosis
• D. Coarctation of the aorta

Answer: (B)

Hypertension with unexplained hypokalemia points to mineralocorticoid excess causing potassium loss. Primary aldosteronism occurs when the adrenal cortex makes aldosterone autonomously, leading to sodium retention and volume expansion that raises blood pressure, while aldosterone also increases potassium and hydrogen ion excretion, causing hypokalemia and often metabolic alkalosis. This combination—persistent hypertension plus hypokalemia without another clear cause—strongly suggests autonomous aldosterone production. The expected lab pattern is a high aldosterone level with suppressed renin, producing a high aldosterone-to-renin ratio, which is then confirmed with further testing and imaging to distinguish an adenoma from bilateral adrenal hyperplasia.

Pheochromocytoma would more likely present with episodic hypertension and symptoms like headaches, sweating, and tachycardia due to catecholamine surges. Renal artery stenosis can cause secondary hyperaldosteronism with hypertension and hypokalemia, but renin levels are typically elevated and there may be findings such as an abdominal bruit or differing kidney function. Coarctation of the aorta presents with upper-body hypertension and diminished femoral pulses or leg claudication, not with isolated hypokalemia.