Falsely elevated plasma ACTH levels measured by the Elecsys assay related to heterophilic antibody in a case of secondary adrenocortical insufficiency

Endocrine journal

Yutaka Oki¹  Michiko Kimura²  Koji Morita³  Masumi Ogawa⁴  Yuta Okawa⁵ 

[1] Department of Family and Community Medicine, Hamamatsu University School of Medicine, Hamamatsu 431-3192, Japan;Department of Laboratory Medicine, Teikyo University School of Medicine, Tokyo 173-8606, Japan;Division of Endocrinology and Metabolism, Department of Internal Medicine, Teikyo University School of Medicine, Tokyo 173-8606, Japan;Division of Metabolism, Department of Internal Medicine, Self-Defense Forces Central Hospital, Tokyo 154-8532, Japan;Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, Hamamatsu 431-3192, Japan

关键词: Adrenocorticotropic hormone (ACTH);    Adrenal insufficiency;    The Elecsys ACTH assay;    Heterophilic antibody;    Prolonged ACTH stimulation test;   

DOI  :  10.1507/endocrj.EJ19-0023

学科分类：内分泌与代谢学

来源: Japan Endocrine Society

【 摘 要 】

A 49-year-old woman with membranous nephropathy was referred to our hospital during the tapering of oral prednisolone, because of suspicion of primary adrenal insufficiency based on a plasma ACTH level of 399.1 pg/mL in the Elecsys assay and a serum cortisol level of 3.1 μg/dL. A rapid ACTH stimulation test revealed a suboptimal response, whereas a prolonged ACTH simulation test showed a sufficient increase in her urinary free cortisol. Also, big ACTH was not detected by gel exclusion chromatography. Therefore, we speculated that ACTH levels were falsely elevated due to some interference substances. Pretreatment of her plasma with either polyethylene glycol precipitation or a heterophilic blocking tube substantially reduced her ACTH values. When either the Immulite ACTH II or the TOSOH II ACTH was tried instead of the Elecsys ACTH, her plasma ACTH values turned out to be lower and appropriate for her clinical status. These results indicated that heterophilic antibodies interfered only with the Elecsys ACTH assay presumably by bridging the capture and tracer antibodies. To our knowledge, this is the first case in which the Elecsys ACTH assay yielded falsely elevated results. Regardless of the measurement system used, if there is a discordance between assay results and clinical findings, it should be considered to adopt additional procedures and/or another assay.

【 授权许可】

Unknown