Department of Endocrinology, Christie Hospital, Manchester, UK.
Clin Endocrinol (Oxf). 2010 Jan;72(1):17-21. doi: 10.1111/j.1365-2265.2009.03582.x. Epub 2009 Mar 19.
Liquid chromatography-tandem mass spectrometry (LC-MS/MS) eliminates cross-reactivity, which is a major limitation of immunoassays used for the measurement of salivary cortisol (SalC). We aimed to evaluate the potential of SalC measured by LC-MS/MS in patients undergoing assessment of the HPA axis.
Cross-sectional study of 78 patients admitted for routine testing in a specialized endocrine unit.
Matched serum and saliva samples were collected from 68 patients who had a short synacthen test (SST, 250 mcg im) and 10 patients who had an insulin tolerance test (ITT, insulin 0.15 U/kg iv). Serum cortisol (SerC) was measured with an automated immunoassay and SalC with LC-MS/MS. Adequate SerC responses were >500 nmol/l.
In all patients with adequate responses, the relative increase in SalC was significantly higher than that in SerC [6.4(0.3-26.1) vs. 1.0(0.3-4.9), P < 0.0001)]. The SerC-SalC relationship was better explained by an exponential rather than a linear model (R(2)=0.83 vs. R(2)=0.65, both P < 0.0001). Based on 59 patients with adequate SerC responses to an SST, an adequate SalC response was defined as 8.3 nmol/l. Seven patients following an SST and three patients following an ITT showed inadequate responses in both SerC and SalC, but two patients with CBG deficiency showed a low SerC with normal SalC.
We have shown an excellent diagnostic sensitivity and specificity of LC-MS/MS SalC in the assessment of the HPA axis and superiority over SerC when CBG levels are altered. The exponential relationship between SerC and SalC supports the concept of CBG binding capacity saturation.
液相色谱-串联质谱（LC-MS/MS）消除了免疫测定法用于测量唾液皮质醇（SalC）时的交叉反应性，这是一个主要限制。我们旨在评估 LC-MS/MS 测量 SalC 在评估 HPA 轴的患者中的潜力。
在专门的内分泌科进行常规检查的 78 例患者的横断面研究。
从 68 例接受短期合成试验（SST，250mcg im）和 10 例接受胰岛素耐量试验（ITT，静脉内 0.15U/kg 胰岛素）的患者中采集了匹配的血清和唾液样本。使用自动化免疫分析法测量血清皮质醇（SerC），并用 LC-MS/MS 测量 SalC。足够的 SerC 反应大于 500nmol/L。
在所有有足够反应的患者中，SalC 的相对增加明显高于 SerC [6.4(0.3-26.1) vs. 1.0(0.3-4.9)，P<0.0001)]。SerC-SalC 关系通过指数模型而不是线性模型更好地解释（R(2)=0.83 vs. R(2)=0.65，均 P<0.0001）。基于对 59 例 SST 有足够 SerC 反应的患者，将足够的 SalC 反应定义为 8.3nmol/L。7 例 SST 后和 3 例 ITT 后患者的 SerC 和 SalC 反应均不足，但 2 例 CBG 缺乏症患者的 SerC 低而 SalC 正常。
我们已经证明 LC-MS/MS SalC 在评估 HPA 轴方面具有出色的诊断敏感性和特异性，并且在 CBG 水平改变时优于 SerC。SerC 和 SalC 之间的指数关系支持 CBG 结合能力饱和的概念。
