無法偵測腎上腺結節之原發性高醛固酮症
江品葭1，莊燿吉1，黃鏘綺2，劉惠瑛1*
1高雄長庚紀念醫院泌尿科，2高雄長庚紀念醫院腎臟科
Primary aldosteronism without detectable adrenal nodule
Ping-Chia Chiang, Yaw-Chi Chuang, Chiang-Chi Huang, Hui-Ying Liu*
Kaohsiung Chang Kung Memorial Hospital, Department of Urology, Department of Nephrology
Case Report:
A 77-year-old lady with underlying disease of hypertension, type 2 DM, chronic kidney disease had regular internal medicine OPD follow-up in local hospital. ARB and Aldactone were prescribed for her hypertension. Since an unexpected elevated of serum creatinine level was noted in last July, several examinations were then performed. Laboratory data showed increased renin and aldosterone concentration, so she was referred to our hospital for help.
During serial blood examinations, PRA renin level was 47 ng/L and aldosterone level was 464 ng/dL, which indicated a significant elevated aldosterone-renin ratio (ARR). Her baseline SBP was around 140-160mmHg despite medicine usage. The serum potassium was within normal range. Due to suspected primary aldosteronism, abdominal CT was performed but there was no evidence of adrenal mass. By contrast, adrenal vein sampling for ruling out functional adrenal adenoma revealed overproduction of aldosterone from the right adrenal gland (LI: 2.54).
Retroperitoneoscopic right adrenalectomy was performed smoothly. Pathologic results showed micronodular cortical hyperplasia. Microscopic finding included nodular arrangements of cortical cells focally streaming into the surrounding fat (Figure 1). Immunohistochemical stain showed multiple discontinuous clusters of CYP11B2-positive cells are identified underneath the adrenal capsule, which confirmed the diagnosis of micronodular cortical hyperplasia (Figure 2,3). After operation, the patient’s general condition, blood pressure, aldosterone, and renin activity levels returned to normal. No more medication was needed.
Micronodular cortical hyperplasia, one subtype of unilateral adrenal hyperplasia (UAH), is a rare cause of primary aldosteronism. The diagnosis can only be made after surgical removal and by pathological confirm. Since UAH is difficult to detect and may be treated medically, the real incidence is more common than believed. This case indicates that CT imaging is unreliable for diagnosing UAH. Adrenal vein sampling is suggested for accurate diagnosis and suitable further management.