Institute of Biochemistry and Clinical Biochemistry, Catholic University School of Medicine, Rome, Italy. ccarrozza@ rm.unicatt.it
Ann Clin Biochem. 2010 May;47(Pt 3):228-32. doi: 10.1258/acb.2010.010020. Epub 2010 Apr 20.
The diagnosis of Cushing's syndrome (CS) represents a challenge for endocrinologists. Several screening tests are used, but none of them seems to be the gold standard for the diagnosis. The aim of this study was to confirm the diagnostic value of salivary cortisol (SC) as a first-level screening test and to evaluate the clinical performance of a electrochemiluminescence immunoassay (ECLIA) method.
In 33 patients with a strong clinical suspicion of CS, we evaluated urinary free cortisol, circadian rhythm plasma cortisol (PC) and morning PC after low-dose dexamethasone suppression test (LDDST). At the same sampling times, we evaluated SC analysed by the same automated method. Correlation studies were evaluated by Spearman index (significance P < 0.05).
On the basis of biochemical results CS was confirmed in 21/33. SC was significantly correlated to PC at 12:00 and 23:00. Thus, we chose 8.3 nmol/L as midnight SC cut-off value with 100% sensitivity and 97.4% specificity. The cut-off chosen after LDDST was 1.7 nmol/L (100% sensitivity and 72% specificity).
SC assay showed a good clinical accuracy and the ECLIA method can be used in clinical routine to obtain fast results easily.
库欣综合征（CS）的诊断对内分泌学家来说是一个挑战。有多种筛选试验，但似乎都没有成为诊断的金标准。本研究的目的是确认唾液皮质醇（SC）作为一线筛查试验的诊断价值，并评估电化学发光免疫分析（ECLIA）方法的临床性能。
在 33 例临床高度怀疑 CS 的患者中，我们评估了尿游离皮质醇、昼夜节律血浆皮质醇（PC）和小剂量地塞米松抑制试验（LDDST）后的清晨 PC。在相同的采样时间，我们评估了通过相同自动化方法分析的 SC。通过 Spearman 指数评估相关性研究（显著性 P<0.05）。
根据生化结果，33 例患者中有 21 例被确诊为 CS。SC 与 12:00 和 23:00 的 PC 呈显著相关。因此，我们选择 8.3 nmol/L 作为午夜 SC 的截断值，其敏感性为 100%，特异性为 97.4%。LDDST 后的截断值为 1.7 nmol/L（敏感性为 100%，特异性为 72%）。
SC 检测具有良好的临床准确性，ECLIA 法可用于临床常规，以获得快速、简便的结果。
