繰り返しの内分泌学的検査にて診断しえた原発性アルドステロン症の1例

A Case of Primary Aldosteronism Diagnosed by Repeated Hormonal Investigations

要旨　患者は35歳，男性．近医で高血圧症と低K血症を指摘された．原発性アルドステロン症(PA)が疑われたが，血漿レニン活性(PRA)の抑制は認められなかった．若年性高血圧症であるため二次性高血圧症を否定しきれず，当科へ紹介となった．入院後，内分泌学的検査を再検したところPRAの抑制が認められた．更なる精査のために行ったカプトプリル負荷試験も陽性を示し，PAの可能性が強まった．一方，CTなどの画像診断では副腎に形態的異常を認めなかった．診断確定のために施行したACTH負荷副腎静脈サンプリングでは左副腎の有意なアルドステロン過剰分泌が認められ，診断確定に至った．内視鏡的に左副腎摘出術が施行され，術後の病理標本で左副腎腺腫が認められた．PAでは必ずしもPRAの抑制を認めない症例も含まれているものと考えられ，高血圧症例のなかには繰り返して内分泌学的検査を行う必要がある症例も存在すると考えられた．

　A 35-year-old hypertensive and hypokalemic male patient, who demonstrated normorenin values on the first hormonal check, was referred to our institute. Because hypokalemia persisted and he was rather young to have another form of essential hypertension, we suspected secondary hypertension and repeated the hormonal check. A later examination demonstrated suppressed renin and increased aldosterone. Furthermore, the captopril-loading test result suggested PA. However, none of the imaging modalities detected abnormal adrenal structure. Adrenal venous sampling showed significant excessive aldosterone secretion from the left adrenal gland. Therefore, the patient was diagnosed as having PA. Laparoscopic adrenalectomy was performed, and histopathological examination found cortical adenoma. Our case suggested that even if a patient demonstrates normal plasma renin activity and plasma aldosterone concentration, the possibility of PA cannot be entirely excluded. Some patients with PA may be overlooked, especially when hormonal data appear normal on first examination. Repeat hormonal investigations should be considered in cases of hypertension.