二氧化碳结合力/血钾值在库欣综合征病因诊断中的价值探讨

Carbon dioxide combining power/potassium ratio in etiological diagnosis of Cushing＇s syndrome

目的 探讨二氧化碳结合力/血钾值（CO2 CP/K）对库欣综合征病因诊断的价值.方法 回顾性分析1993至2015年解放军总医院内分泌科收治的确诊为库欣综合征、资料齐全的489例患者的临床资料.489例中,促肾上腺皮质激素（ACTH）依赖性库欣综合征243例;非ACTH依赖性库欣综合征246例,其中垂体性库欣综合征（库欣病）214例,异位ACTH综合征29例.应用受试者工作特征曲线对CO2CP/K的诊断价值进行探讨,得出敏感度与特异度均较高的最佳诊断切点.结果 ①与非ACTH依赖性库欣综合征组相比,ACTH依赖性库欣综合征组的血钾水平更低[（3.46±0.77）与（3.69±0.57） mmol/L],CO2 CWK（10.0±5.5与7.6±2.1）更高（t=3.433,P=0.001;t=-3.612,P=0.000）.与库欣病组相比,异位ACTH综合征组血钾[（2.47±0.63）与（3.62 f0.67） mmol/L]及血氯水平更低;二氧化碳结合力、碳酸氢根、碱剩余水平及CO2 CP/K（15.6±8.0与7.8±2.4）更高（t=-10.145,P=0.000）.2组血钠及pH值差异均无统计学意义（t值分别为1.170和-1.459,均P＞0.05）.②以ACTH依赖性库欣综合征组为病例组,CO2CWK切点为8.95时灵敏度为0.34、特异度为0.85;以异位ACTH综合征组为病例组CO2CP/K切点为9.09时灵敏度0.89、特异度0.78.结论 CO2 CP/K对ACTH依赖性及ACTH非依赖性库欣综合征诊断价值有限,在一定程度上可以区分库欣病和异位ACTH综合征,便于库欣综合征的病因诊断的初筛.

Objective To evaluate carbon dioxide combining power/potassium ratio （CO2CP/K） in etiological diagnosis of Cushing＇s syndrome.Methods The clinical data 489 patients with pathohistologically confirmed Cushing＇s syndrome treated in PLA General Hospital between 1993 and 2015 were retrospectively reviewed.Among 489 patients,there were 246 cases of adrenocorticotropic hormone （ACTH） nondependent Cushing＇s syndrome and 243 cases of ACTH dependent Cushing＇s syndrome,including 214 cases of Cushing＇s disease （CD） and 29 cases of ectopic ACTH syndrome （EAS）.Receiver operating characteristic（ROC） curve was used to evaluate efficacy of CO2CP/K for etiological diagnosis and the cut-off value and corresponding sensitivity and specificity were analyzed.Results Blood potassium levels were lower in ACTH nondependent group than those in ACTH dependent group [（3.46 ± 0.77） vs.（3.69 ±0.57） mmol/L,t =3.433,P =0.001].Bicarbonate,base excess and CO2CP/K （10.0 ±5.5 vs.7.6 ± 2.1） were higher in ACTH nondependent group than those in ACTH dependent group （t =-3.612,P =0.000）.There was no significant difference in serum sodium,carbon dioxide binding force and pH value between two groups （P 〉 0.05）.Blood potassium [（2.47 ± 0.63） vs.（3.62 ± 0.67） mmol/L] and chlorine levels were lower in EAS group than those in CD group.Bicarbonate,base excess and CO2 CP/K （15.6±8.0 vs.7.8±2.4） were higher in EAS group than those in CD group （t =-10.145,P=0.000）.There was no significant difference in serum sodium,carbon dioxide binding force and PH value between two groups （P 〉 0.05）.Taking 8.95 as cut-off value the sensitivity and specificity of CO2 CP/K in diagnosis of ACTH dependent Cushing＇s syndrome were 0.34 and 0.85,while taking 9.09 as cut-off value the sensitivity and specificity of CO2CP/K in diagnosis of EAS were 0.89 and 0.78,respectively.Conclusions The value of CO2CP/K is limited in distinguishing between ACTH dependent and non-ACTH independent Cushing,s syndrome.It may distinguish CD from EAS to some extent,indicating that it might be used as the screening method for etiological diagnosis.