Endocrine Abstracts

Introduction: Hypokalemia is considered as a late manifestation of primary aldosteronism (PA), long preceded by hypertension. However, there have been reports of normotensive PA patients presenting with hypokalemia. This study aims to examine the relationship of hypokalemia and blood pressure in patients with hyperaldosteronism.

Methods: A retrospective review of patients who underwent saline infusion test (SIT) from 2014 to 2016 was conducted. All patients had screening plasma aldosterone concentration (PAC): plasma renin activity (PRA) ratio of >20. Postinfusion PAC level <5 ng/dl (139 pmol/l) indicated normal aldosterone suppression, PAC >10 ng/dl (277 pmol/l) confirmed PA, whereas PAC 5–10 ng/dl (139–277 pmol/l) was regarded as indeterminate. Hypokalemia was defined as serum potassium <3.5 mmol/l.

Results: Over a 3-year period, 52 patients referred for hypokalemia had non-suppressible postinfusion PAC (>5 ng/dl). They comprised of 36 men and 16 women, with a mean age of 58.4±9.1 and 57.3±13.2 years respectively.

In the PA group consisting of 26 men and 11 women, the mean serum potassium were 2.9±0.3 mmol/l and 2.7±0.5 mmol/l respectively. Eighteen (69.2%) men and 10 (90.9%) women were on ≤2 antihypertensive agents, including two women (age 48 and 51) with severe hypokalemia (<2.5 mmol/l) who were normotensive and rendered normokalemic after adrenalectomy and spironolactone treatment separately.

In the indeterminate group comprising of ten men and five women, the mean serum potassium were 3.1±0.2 mmol/l and 3.0±0.2 mmol/l respectively. Five (50%) men and 4 (80%) women were on ≤2 antihypertensive agents.

In all patients with moderate to severe hypokalemia (≤2.9 mmol/l), 7/11 (63.6%) men and 8/9 (88.9%) women were on ≤2 antihypertensive agents.

Conclusion: In our cohort of Asian patients, majority with hypokalemia secondary to autonomous aldosterone production required only 0–2 antihypertensive agents, even in those with more severe degree of hypokalemia. This suggests possible differential effects of aldosterone excess on potassium homeostasis and blood pressure.