Development and Validation of a 0.5 mg Dexamethasone Suppression Test as an Initial Screening Test for the Diagnosis of ACTH-dependent Cushing’s Syndrome

Yutaka OKI; Kozo HASHIMOTO; Yukio HIRATA; Yasumasa IWASAKI; Takeshi NIGAWARA; Masaru DOI; Satoru SAKIHARA; Kazunori KAGEYAMA; Toshihiro SUDA

doi:10.1507/endocrj.K09E-194

ORIGINALS

Development and Validation of a 0.5 mg Dexamethasone Suppression Test as an Initial Screening Test for the Diagnosis of ACTH-dependent Cushing’s Syndrome

Yutaka OKI, Kozo HASHIMOTO, Yukio HIRATA, Yasumasa IWASAKI, Takeshi NIGAWARA, Masaru DOI, Satoru SAKIHARA, Kazunori KAGEYAMA, Toshihiro SUDA

Author information

Yutaka OKI
Second Division, Department of Medicine, Hamamatsu University School of Medicine, Shizuoka, Japan
Kozo HASHIMOTO
Department of Endocrinology, Metabolism and Nephrology, Kochi Medical School, Kochi University, Kochi, Japan
Yukio HIRATA
Department of Clinical and Molecular Endocrinology, Tokyo Medical and Dental University Graduate School, Tokyo, Japan
Yasumasa IWASAKI
Department of Endocrinology, Metabolism and Nephrology, Kochi Medical School, Kochi University, Kochi, Japan
Takeshi NIGAWARA
Department of Endocrinology and Metabolism, Hirosaki University Graduate School of Medicine, Aomori, Japan
Masaru DOI
Department of Clinical and Molecular Endocrinology, Tokyo Medical and Dental University Graduate School, Tokyo, Japan
Satoru SAKIHARA
Department of Endocrinology and Metabolism, Hirosaki University Graduate School of Medicine, Aomori, Japan
Kazunori KAGEYAMA
Department of Endocrinology and Metabolism, Hirosaki University Graduate School of Medicine, Aomori, Japan
Toshihiro SUDA
Department of Endocrinology and Metabolism, Hirosaki University Graduate School of Medicine, Aomori, Japan

Keywords: ACTH-dependent Cushing’s syndrome, Cushing’s disease, Dexamethasone suppression test, Screening

JOURNAL FREE ACCESS

2009 Volume 56 Issue 7 Pages 897-904

DOI https://doi.org/10.1507/endocrj.K09E-194

View "Advance Publication" version (August 25, 2009).

Details

Abstract

For the diagnosis of Cushing’ s syndrome (CS), the overnight 1 mg dexamethasone suppression test (DST) has been widely used as a standard low-dose DST. However, it is evident that 1 mg DST may not be sensitive enough to detect CS when the cortisol cut-off concentration is 5 μg/dL. Therefore, we developed and validated 0.5 mg DST as a new screening method for diagnosis of ACTH-dependent CS. To compare 0.5 mg DST with 1 mg DST, 110 patients with ACTHdependent CS were enrolled, including 88 with Cushing’ s disease (CD), 8 with subclinical CD and 14 with ectopic ACTH syndrome, as well as 134 control subjects. Subjects were given either 0.5 mg or 1 mg dexamethasone orally at 23:00 on different days, with blood samples collected the following morning between 8:00 and 9:00 to determine plasma cortisol concentration. The area under the receiver operator characteristics curve observing the 0.5 mg DST was higher than that of the 1 mg DST. The most sensitive and specific cut-off value of plasma cortisol concentration using 0.5 mg DST was found to be 3.05 μg/dL with 99.1% sensitivity and 98.4% specificity, identical to the 3 μg/dL cut-off currently used in the Japanese guideline for diagnosis of subclinical CD. In conclusion, 0.5 mg DST is a sensitive and specific screening test for diagnosis of ACTH-dependent CS. We recommend 0.5 mg DST with a cortisol cut-off concentration of 3 μg/dL to be used as the initial step in diagnosing ACTH-dependent CS.

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