评价不同剂量（1 mg和2 mg）过夜地塞米松抑制试验（ODST）在库欣综合征筛查中的诊断价值，探究最佳筛查药物剂量和诊断切点，以提高临床工作中对该疾病的检出率，减少药物对人体可能造成的不良反应。

回顾性分析从2000年1月至2017年12月山东大学附属省立医院内分泌代谢病科收治并确诊的96例库欣综合征患者及61例临床怀疑经完善检查排除库欣综合征的患者的临床资料，在相同诊断切点下，比较不同剂量试验后血清皮质醇抑制程度及诊断敏感性、特异性；在相同剂量药物下，比较不同诊断切点在疾病筛查中的敏感性、特异性。

在1 mg过夜地塞米松抑制试验中，库欣综合征组皮质醇抑制率为17.9%，非库欣综合征组为78.7%；在2 mg过夜地塞米松抑制试验中，库欣综合征组皮质醇抑制率为24.2%，非库欣综合征组为87.2%。以试验当天8:00血清皮质醇为基础值，以次日8:00血清皮质醇<50 nmol/L（1.8 μg/dl）为库欣综合征诊断切点，1 mg ODST诊断库欣综合征的敏感性、特异性分别为为100%、42.8%；2 mg ODST诊断库欣综合征的敏感性及特异性分别为100%、69.7%；若以次日8:00血清皮质醇<138 nmol/L（5 μg/dl）为库欣综合征诊断切点，1 mg ODST诊断库欣综合征的敏感性、特异性分别为为100%、85.7%，2mg ODST诊断库欣综合征的敏感性、特异性为100%、93.9%。在库欣综合征的筛查中，在相同诊断切点下，2 mg ODST比1 mg ODST诊断结果更可靠；在相同剂量药物下，以次日8:00血清皮质醇<138 nmol/L（5 μg/dl）作为诊断切点，诊断敏感性无明显差别，特异性更高,诊断更准确。

综上所述，在库欣综合征筛查过程中，以次日8:00血清皮质醇<138 nmol/L（5 μg/dl）为库欣综合征诊断切点，进行2 mg ODST的诊断准确性明显提高，诊断结果更为可靠，值得在实践中推广应用。

To evaluate the diagnostic value of different doses (1 mg and 2 mg) of overnight dexamethasone suppression test (ODST) in the screening of Cushing's syndrome, and to explore the optimal screening drug dose and cut point; in order to increase the detection rate of this disease in clinical work, and to reduce the adverse reactions that the drug may cause to human body.

A retrospective analysis was performed on the clinical data of 96 patients with Cushing's syndrome (the Cushing's syndrome group) and 61 clinical suspected cases (the non-Cushing's syndrome group) admitted to the Department of Endocrinology and Metabolism of the Provincial Hospital Affiliated to Shandong University from Jan. 2000 to Dec. 2017. Under the same diagnostic cut-point, the degree of serum cortisol inhibition, diagnostic sensitivity, specificity, and false-positive rate after different dose tests were compared. And at the same dose of drug, the sensitivity and specificity of different diagnostic cut-points in disease screening were compared.

In the 1-mg ODST, the cortisol inhibition rate was 17.9% in the Cushing's syndrome group and 78.7% in non-Cushing's syndrome group. And in the 2-mg ODST, the cortisol inhibition rate was 24.2% in the Cushing's syndrome group, compared with 87.2% in the non-Cushing syndrome group. When taking the serum cortisol at 8:00 on the day of the test as basal value and taking serum cortisol < 50 nmol/L (1.8 μg/dl) on the following day as the diagnosis cut-off point for Cushing's syndrome, the diagnostic sensitivity and specificity for the 1-mg ODST were 100% and 42.8%, respectively; and that for the 2-mg ODST were 100%, and 69.7%, respectively. If taking serum cortisol < 138 nmol/L (5 μg/dl) on the following day as the diagnosis cut-off point, the sensitivity and specificity of 1-mg ODST in the diagnosis of Cushing's syndrome are 100% and 85.7%, respectively; and that for the 2-mg ODST were 100% and 93.9%, respectively. In the screening of Cushing's syndrome, 2-mg ODST was more accurately than 1-mg ODST at the same diagnostic site. And at the same dose, taking serum cortisol at 8:00 on the following day was <138 nmol/L (5 μg/L). Dl) as the diagnostic cut point brought no significant difference in diagnostic sensitivity, but could give higher specificity and more accurate diagnosis rate.

In the screening process of Cushing's syndrome, when taking the serum cortisol at 8:00 on the following day <138 nmol/L (5 μg/dl) as the diagnosis point of Cushing syndrome, the diagnosis accuracy rate of 2-mg ODST improved significantly with more accurate diagnose result, which is worth popularizing and applying in practice.