THE INVISIBLE EVIL TWIN OF AN ADRENAL ADENOMA

Abstract

INTRODUCTION
Primary aldosteronism (PA) causes a persistently elevated blood pressure (BP) due to excessive release of the hormone aldosterone from the adrenal glands. It can be cured with
surgical resection of the aldosterone-secreting adenoma leading to resolution of hypertension and reduction in cardiovascular risk. There is known discordance between identification of adenoma with computed tomography (CT) and confirmation of aldosterone hypersecretion with adrenal venous sampling (AVS).

CASE
We present the case of a man with previous ischemic heart disease who presented with resistant hypertension. He had been diagnosed with essential hypertension 5 years prior. Investigations for secondary causes of hypertension were performed, as he subsequently required 5 anti-hypertensive medications to control his hypertension. Work-up revealed an elevated serum aldosterone of 924 pmol/L [normal range (NR) 111 to 860] with suppressed plasma renin activity of 0.4 ng/mL/hr (NR 1.5 to 5.7); and aldosteroneto-renin ratio of 2060 (NR <750). Saline suppression test confirmed the diagnosis, with failure of suppression of aldosterone with salt loading. CT of the adrenal glands revealed a left adrenal adenoma measuring 1.4 cm x 1.5 cm with a Hounsfield Unit (HU) of 12 and absolute washout of 60%. The right adrenal gland was normal. AVS was performed. There was lateralisation to the right adrenal gland indicating aldosterone hypersecretion but with normal adrenal imaging. The Lateralisation index ratio was 8.6 (NR <3). The patient subsequently underwent a repeat AVS which produced similar results. One month later, he underwent laparoscopic right adrenalectomy which improved his BP control. Histologic features were consistent with adrenal cortical adenoma.

CONCLUSION
This case highlights the importance of recognizing the need to investigate for secondary causes of hypertension. It also underscores the importance of dynamic tests such as AVS to confirm hypersecretion of aldosterone from the correct adrenal gland resulting in the best treatment option.