糖化血红蛋白对诊断和筛查甲状腺功能亢进患者糖代谢异常的意义

目的 探讨对甲状腺功能亢进（甲亢）患者采用糖化血红蛋白（HbA1c）筛查糖尿病（DM）及糖尿病前期的敏感性和特异性，并确定相应的最佳切点。方法 收集2013～2015年在安徽省立医院内分泌科住院并行75 g口服葡萄糖耐量试验（OGTT）试验的甲亢患者共305例，同时检测HbA1c，测量身高和体质量，计算体质量指数（BMI），采用受试者工作特征曲线（ROC曲线）获得HbA1c诊断和筛查糖尿病及糖尿病前期的相关切点。结果 ①依据ROC曲线判定，该组人群中HbA1c诊断糖尿病的最佳临界点为5.55%，敏感性为72.4%，特异性为73.2%，此界点将漏诊6.9%的DM人群，并纳入26.8%糖耐量正常人群和35.2%糖尿病前期人群。HbA1c筛查糖尿病前期的最佳临界点为5.45%，敏感性为56.9%，特异性为61.9%。②糖耐量正常组（NGT）、糖尿病前期组（IGR）、糖尿病组（DM）的HbA1c水平依次升高，差异有统计学意义（P<0.05）。结论 HbA1c可较准确反映甲亢患者不同阶段的糖代谢异常状态，其在甲亢患者中诊断和筛查糖尿病及糖尿病前期的ROC切点分别为5.55%与5.45%。

Value of glycated hemoglobin in screening and diagnosis of abnormal glycometabolism in patients with hyperthyroidism

Objective To evaluate the sensitivity and specificity of glycated hemoglobin (HbA1c) in screening diabetes mellitus (DM) and prediabetic state in the patients with hyperthyroidism, and to identify the optimal HbA1c cut-off point.Methods 305 cases of patients with hyperthyroidism, ever hospitalized in our hospital from 2013 to 2015 and detected by the oral glucose tolerance test (OGTT), were recruited into the study.Their HbA1c levels were measured, together with their height and body mass for body mass index (BMI) at the same time.The optimal HbA1c cut-off points for screening and diagnosis of DM and prediabetic state were identified by means of receiver operating characteristic (ROC) curve.Results According to the ROC curve, the optimal cut-off point of HbA1c for DM diagnosis in these patients with hyperthyroidism was 5.55%, with a sensitivity of 72.4% and a specificity of 73.2%.However, 6.9% DM patients would be missed on the threshold, and simultaneously 26.8% patients with normal glucose tolerance (NGT) and 35.2% in prediabetic state should not be included.Similarly, the optimal cut-off point of HbA1c for prediabetic state screening was 5.45%, with a sensitivity of 56.9% and a specificity of 61.9%.The blood levels of HbA1c in the NGT patients were the lowest, and in the DM patients they were the highest, with significant differences among the three groups of patients (all P<0.05).Conclusion The blood levels of HbA1c could reliably reflect the abnormal glycometabolism at different stages in the patients with hyperthyroidism, and the ROC cut-off points of HbA1c for diagnosis and screening of DM and prediabetic state are 5.55% and 5.45%, respectively.