Approach to the patient with hypertension, unexplained hypokalemia, and metabolic alkalosis.

We present a patient with hypertension and hypokalemia secondary to an aldosterone-producing adenoma that was renin responsive (APARR). We discussed the sequential approach to the diagnosis of the different subtypes of primary aldosteronism and confirmed the presence of an APARR. The most common cause of primary aldosteronism is an aldosteronoma; functionally, these adenomas respond poorly to angiotensin II but show a brisk response to adrenocorticotropin hormone. They have a pattern of aldosterone level that declines in parallel with cortisol levels. Our patient had an APARR, with an increase of aldosterone in the upright posture. The unusual physiologic response, incidence, and clinical characteristics of APARR are reviewed.