[Hypokalemia, a key clinical data for diagnosing primary hyperaldosteronism]

We report a case of a 37 year-old man with a long history of hypertension under treatment, who was admitted at our institution with intense fatigue and weakness of lower limbs. The laboratory results at Emergency Department showed severe hypokalemia. A study of secondary hypertension was carried out. With the initial suspicion of primary hyperaldosteronism, complete blood test was done including plasma renine activity, which was completely suppressed, and plasma aldosterone concentration, which resulted normal. Likewise, an abdomen CT was performed and revealed a left adrenal mass consistent of suprarrenal adenoma. Therefore, a salt loading suppression test was done with subsequent measure of plasmatic renine activity, which was still suppressed, plasma aldosterone concentration, that persisted normal, and a 24-h urinary aldosterone excretion rate, which was clearly high, supporting the suspected diagnosis. After the adrenalectomy, the patient remained asymptomatic with normal blood pressure without treatment and with normal serum potassium levels.