Arafat Ayman M, Möhlig Matthias, Weickert Martin O, Perschel Frank H, Purschwitz Johannes, Spranger Joachim, Strasburger Christian J, Schöfl Christof, Pfeiffer Andreas F H
Department of Endocrinology, Diabetes and Nutrition, Charité-University Medicine Berlin, Campus Benjamin Franklin, Hindenburgdamm 30, 12200 Berlin, Germany.
J Clin Endocrinol Metab. 2008 Apr;93(4):1254-62. doi: 10.1210/jc.2007-2084. Epub 2008 Jan 2.
Besides the measurement of IGF-I, GH suppression during an oral glucose tolerance test is recommended to assess the biochemical status in acromegaly. However, the development of highly sensitive and specific GH assays necessitates a critical reevaluation of criteria for diagnosis and follow-up of disease activity.
Our objective was to evaluate the between-method discrepancies in GH determinations by different immunoassays considering further confounders like age, gender, and body mass index (BMI). DESIGN, SUBJECTS, AND METHODS: We measured GH during a 75-g oral glucose tolerance test in 46 acromegaly patients (18 controlled, 28 uncontrolled; 19 men; 31-63 yr; BMI 26.4 +/- 0.4 kg/m(2)) and 213 healthy subjects (66 men; 20-76 yr; BMI 30 +/- 0.5 kg/m(2)), using three different commercially available assays [Immulite (Diagnostic Products Corp., Los Angeles, CA), Nichols (Nichols Institute Diagnostika GmbH, Bad Vilbel, Germany), and Diagnostic Systems Laboratories (Sinsheim, Germany)] that were calibrated against the recently recommended GH standards.
Results from all assays strongly correlated (r = 0.8-0.996; P < 0.0001). However, the results obtained with the Immulite assay were, on average, 2.3-fold higher than those obtained with Nichols and 6-fold higher than those obtained with Diagnostic Systems Laboratories. Using cutoff limits of 1 microg/liter (Immulite) and 0.5 microg/liter (Nichols) identified 95% of patients with active disease and 78-80% of patients in remission. Basal and nadir GH levels were significantly higher in females than in males (Immulite 2.2 +/- 0.28 microg/liter vs. 0.73 +/- 0.15 microg/liter and 0.16 +/- 0.01 microg/liter vs. 0.08 +/- 0.01 microg/liter; P < 0.001, respectively). In multiple regression analysis, age, BMI, and gender were predictors for basal and nadir GH levels.
Postglucose GH-nadir values are assay, gender, age, and BMI specific, indicating the need of individual cutoff limits for each assay.
除了测量胰岛素样生长因子-1（IGF-I）外，建议在口服葡萄糖耐量试验期间进行生长激素（GH）抑制试验，以评估肢端肥大症的生化状态。然而，高灵敏度和特异性GH检测方法的发展需要对疾病活动的诊断和随访标准进行严格的重新评估。
我们的目的是评估不同免疫分析方法在测定GH时的方法间差异，并考虑年龄、性别和体重指数（BMI）等其他混杂因素。设计、研究对象与方法：我们使用三种不同的市售检测方法[免疫发光分析仪（Immulite，诊断产品公司，加利福尼亚州洛杉矶）、尼科尔斯检测法（Nichols，尼科尔斯诊断研究所有限公司，德国巴特维尔贝尔）和诊断系统实验室检测法（德国辛斯海姆）]，在46例肢端肥大症患者[18例病情得到控制，28例未得到控制；19例男性；年龄31 - 63岁；BMI 26.4±0.4kg/m²]和213名健康受试者[66例男性；年龄20 - 76岁；BMI 30±0.5kg/m²]的75g口服葡萄糖耐量试验期间测量GH，这些检测方法均根据最近推荐的GH标准进行了校准。
所有检测方法的结果高度相关（r = 0.8 - 0.996；P < 0.0001）。然而，免疫发光分析仪检测法得到的结果平均比尼科尔斯检测法高2.3倍，比诊断系统实验室检测法高6倍。使用1μg/L（免疫发光分析仪）和0.5μg/L（尼科尔斯检测法）的临界值可识别出95%的疾病活动期患者和78 - 80%的缓解期患者。女性的基础GH水平和最低点GH水平显著高于男性（免疫发光分析仪检测法：2.2±0.28μg/L对0.73±0.15μg/L，最低点：0.16±0.01μg/L对0.08±0.01μg/L；P均< 0.001）。在多元回归分析中，年龄、BMI和性别是基础GH水平和最低点GH水平的预测因素。
葡萄糖负荷后GH最低点值因检测方法、性别、年龄和BMI而异，这表明每种检测方法都需要有各自的临界值。
