库欣综合征患者小剂量与大剂量地塞米松抑制试验之间的关系

目的 探讨库欣综合征患者小剂量地塞米松抑制试验中血清皮质醇水平抑制程度与大剂量地塞米松抑制试验可受抑制(血清皮质醇水平被抑制50%以上)之间的关系,及其对库欣病的诊断价值.方法 回顾性分析广州中山大学附属第二医院1990年1月至2009年1月收治的91例库欣综合征患者,观察过夜小剂量(1 mg)地塞米松抑制试验中血清皮质醇水平被抑制20%、30%、40%和50%以上与过夜大剂量(8 mg)地塞米松抑制试验可受抑制之间的关系,并比较上述各切点对库欣病诊断的敏感性与特异性.结果 在过夜1 mg地塞米松抑制试验中血清皮质醇水平被抑制的程度(较基础08:00血清皮质醇水平下降的百分比)与在过夜8 mg地塞米松抑制试验中血清皮质醇水平被抑制的程度相关(r=0.649,P<0.001);在过夜1 mg地塞米松抑制试验中血清皮质醇水平被抑制20%、30%、40%和50%以上的例数分别为30、22、13和9例.在这些患者中,过夜8 mg地塞米松抑制试验可受抑制的例数分别为23例(76.7%)、20例(90.9%)、12例(92.3%)和9例(100.0%).血清皮质醇水平被1 mg地塞米松抑制20%、30%、40%和50%以上对库欣病诊断的敏感性分别为52.8%、32.7%、22.6%和15.7%,特异性分别为94.7%、94.7%、97.4%和97.4%.结论 对于库欣综合征患者,若血清皮质醇水平可被过夜1 mg地塞米松抑制20%以上者,大多数也可被过夜8 mg地塞米松抑制试验所抑制,并且其大多数为库欣病患者.

Relationship between low- and high-dose dexamethasone suppression test in patients with Cushing syndrome

Objective To investigate the relationship between the degree of serum cortisol suppression by low-dose dexamethasone (1 mg) and full serum cortisol suppression (suppression rate > 50% ) by high-dose dexamethasone (8 mg) in patients with Cushing syndrome, and to evaluate these tests in Cushing disease. Methods Ninty-one patients with Cushing syndrome were studied retrospectively. The relationship of 20%, 30%, 40%, and 50% cortisol suppression by overnight 1mg dexamethasone with full serum cortisol suppression by overnight 8 mg dexamethasone was analyzed, and the sensitivity and specificity in the diagnosis of Cushing disease were evaluated. Results The degree of cortisel suppression during overnight 1 mg dexamethasone suppression test was correlated with that during overnight 8 mg dexamethasone suppression test (r=0. 649,P<0. 001 ). 30, 22, 13, and 9 patients had greater than 20%, 30%, 40%, and 50% serum cortisol suppression respectively during overnight 1 mg dexamethasone suppression test. Among them, 23 ( 76. 7% ), 20 (90. 9% ), 12 (92.3%), and 9 ( 100.0% )patients had full serum cortisol suppression during overnight 8 mg dexamethasone suppression test. The sensitivity of the cutoff of greater than 20%, 30%, 40%, and 50% serum cortisol suppression for the diagnosis of Cushing disease was 52.8%, 32.7%, 22.6%, and 15.7%, and the specificity was 94.7%, 94.7%, 97.4%, and 97.4% respectively. Conclusions In patients with Cushing syndrome, greater than 20% serum cortisol suppression during overnight 1 mg dexamethasone suppression test is usually associated with full serum cortisol suppression during overnight 8 mg dexamethasone suppression test, and most of them are finally diagnosed as Cushing disease.