Martin N M, Dhillo W S, Banerjee A, Abdulali A, Jayasena C N, Donaldson M, Todd J F, Meeran K
Department of Endocrinology, Imperial College, Faculty of Medicine, Hammersmith Hospital, London W12 0NN, United Kingdom.
J Clin Endocrinol Metab. 2006 Jul;91(7):2582-6. doi: 10.1210/jc.2005-2143. Epub 2006 May 2.
The low-dose dexamethasone suppression test (LDDST) is widely used in confirming a diagnosis of Cushing's syndrome. CRH administration at the end of an LDDST has been reported to improve the diagnostic accuracy of this test.
Our objective was to assess whether CRH administration after a standard LDDST (LDDST-CRH test) improves diagnostic accuracy in Cushing's syndrome.
DESIGN, SETTING, AND PARTICIPANTS: Thirty-six individuals with a clinical suspicion of Cushing's syndrome each completed a standard LDDST and an LDDST-CRH test at Hammersmith Hospitals NHS Trust, London. The LDDST involved administration of 0.5 mg oral dexamethasone given 6-hourly for 48 h. Serum cortisol was measured 6 h after the last dose of dexamethasone, with a value of 50 nmol/liter or below excluding Cushing's syndrome. Immediately after this, the LDDST-CRH test commenced with administration of a ninth dose of 0.5 mg dexamethasone. Exactly 2 h later, 100 mug human-sequence CRH was administered. Serum cortisol was measured 15 min after the CRH injection, with a value of less than 38 nmol/liter also excluding Cushing's syndrome.
Diagnosis or exclusion of Cushing's syndrome was the main outcome measure.
Twelve subjects were diagnosed with Cushing's syndrome (eight Cushing's disease and four primary adrenal). The sensitivity of the LDDST in diagnosing Cushing's syndrome was 100%, with a specificity of 88%. In contrast, although the sensitivity of the LDDST-CRH test was also 100%, specificity was reduced at 67%. These results give a positive predictive value of 80% for the LDDST and 60% for the LDDST-CRH test.
This small study suggests that the addition of CRH to the LDDST does not improve the diagnostic accuracy of the standard LDDST in Cushing's syndrome.
低剂量地塞米松抑制试验（LDDST）被广泛用于库欣综合征的诊断确认。据报道，在LDDST结束时给予促肾上腺皮质激素释放激素（CRH）可提高该试验的诊断准确性。
我们的目的是评估在标准LDDST（LDDST-CRH试验）后给予CRH是否能提高库欣综合征的诊断准确性。
设计、地点和参与者：36名临床怀疑患有库欣综合征的个体在伦敦哈默史密斯医院国民保健服务信托基金各自完成了一项标准LDDST和一项LDDST-CRH试验。LDDST包括每6小时口服0.5毫克地塞米松，共服用48小时。在最后一剂地塞米松服用6小时后测量血清皮质醇，血清皮质醇值为50纳摩尔/升或更低可排除库欣综合征。在此之后，立即开始LDDST-CRH试验，给予第九剂0.5毫克地塞米松。正好2小时后，给予100微克人序列CRH。在注射CRH后15分钟测量血清皮质醇，血清皮质醇值小于38纳摩尔/升也可排除库欣综合征。
库欣综合征的诊断或排除是主要观察指标。
12名受试者被诊断为库欣综合征（8例库欣病和4例原发性肾上腺皮质增生）。LDDST诊断库欣综合征的敏感性为100%，特异性为88%。相比之下，虽然LDDST-CRH试验的敏感性也为100%，但特异性降至67%。这些结果使得LDDST的阳性预测值为80%，LDDST-CRH试验的阳性预测值为60%。
这项小型研究表明，在LDDST中添加CRH并不能提高标准LDDST对库欣综合征的诊断准确性。
