SAT-054 A Curious Case of Aldosteronoma without Hypertension

Primary aldosteronism is an underdiagnosed cause of hypertension. Classically, primary hyperaldosteronism presents with hypertension and hypokalemia, although hypokalemia is not necessary to diagnose this condition. We present here a curious case of Aldosteronoma presenting without hypertension. 64-year-old lady with history of Crohn’s disease s/p colectomy and end-ileostomy in 1992 with chronic high output from ileostomy and non-anion gap metabolic acidosis with hypokalemia. Given CKD stage 4, she was being evaluated for renal transplant. She had a right adrenal incidentaloma noted on CT of the abdomen in 2013 measuring 3.2 x 2.5 cm. Repeat CT abdomen in 2015 showed the adenoma had very minimally enlarged in size and measured 3.6 x 2.7 cm. It was well circumscribed, low density with 27 HU. No adrenal washout was performed. She had no symptoms or signs suggesting pheochromocytoma or Cushing syndrome. She was noted to have chronic hypokalemia needing oral potassium supplementation three times a day. She has always been normotensive. She had normal levels of plasma metanephrines, a positive dexamethasone suppression test with cortisol being 3.7 mcg/dL but a normal midnight salivary cortisol level of 0.03 mcg/dL and a normal DHEAS level of 246 mcg/dL. Her 8 AM aldosterone level was 2860 ng/dL (upright <= 39.2 ng/dL, supine <= 23.2 ng/dL) with a direct renin level of 7.4 pg/mL (3.1 - 57.1 pg/mL). A repeated level of morning aldosterone was still very high at 2380 ng/dL with a direct renin of 9 pg/mL. Given such unusual high levels of aldosterone without hypertension, her blood sample was sent to Mayo clinic lab for confirmation. The lab results from Mayo confirmed the elevated aldosterone level at 1950 ng/dL (ref < 21 ng/dL). Given the right adrenal adenoma with significantly elevated aldosterone level, she underwent a robot-assisted right retroperitoneal adrenalectomy in January 2017. The pathology was consistent with a 3.8 x 2.6 x 2.1 cm adrenocortical adenoma. Her aldosterone level improved to 440 ng/dL with direct renin of 280 pg/mL. These levels were drawn while she was admitted at another hospital for hyponatremia a week after her surgery. Her latest aldosterone level is 142 ng/dL with a direct renin of 49.3 pg/mL. Hypokalemia has resolved and potassium is currently 4.4 mmol/L (3.5 - 5 mmol/L. Her blood pressure remains normal. There have been a few case reports of patients with primary aldosteronism presenting with normal blood pressure. Studies also have looked at such patients to see if they eventually develop hypertension after a few years. ‘Subclinical hyperaldosteronism’ has been uses to characterize patients with early disease states. None of the patients studied had as high an aldosterone level as our patient in this vignette. Our case demonstrates that patients with high aldosterone levels and normal BP may have primary aldosteronism. In our case, surgery led to resolution of hypokalemia.