全血分离时间对肠癌患者血浆游离DNA浓度的影响

The Influence of Whole Blood Isolation Time on Plasma Free DNA Concentration in Patients with Intestinal Cancer

目的观察全血分离时间对肠癌患者血浆游离DNA浓度的影响。方法收集23例经病理确诊的晚期结直肠癌患者乙二胺四乙酸（EDTA）抗凝血各6mL,分别于2、6h和30h分离全血并将分离后的血浆置于超低温冰箱保存,以绝对定量聚合酶链式反应（PCR）检测不同时间段分离的血浆游离DNA浓度,并比较其随时间发生的变化。结果 2h分离全血时,血浆游离DNA浓度的中位数为20.00ng/mL,平均数为63.59ng/mL（95%CI：30.26-96.92ng/mL）;6h分离全血时,血浆游离DNA浓度的中位数及平均数分别为12.56ng/mL和16.90ng/mL（95%CI：9.26-24.54ng/mL）;30h分离全血时,血浆游离DNA浓度的中位数及平均数分别为60.90ng/mL和90.64ng/mL（95%CI：59.01-122.27ng/mL）。2h和30h分离的血浆游离DNA浓度显著高于6h分离的浓度（P=0.003,P=0.000）,30h分离的血浆游离DNA浓度与2h分离的浓度比较,差异无统计学意义（P=0.218）。结论获取肿瘤患者全血后应尽快分离全血,延长分血时间可能导致游离DNA降解。

Objective To observe the influence of whole blood isolating time on plasma free deoxyribose nucleic acid（DNA）in patients with intestinal cancer.Methods 6mL of blood anti-coagulated and ethylenediamine tetraacetic acid（EDTA）from 23 patients diagnosed pathologically as advanced colorectal cancer were collected respectively to isolate the whole blood after 2,6and 30 h which then were stored in refrigerator with ultralow temperature.And then the plasma free DNA densities were detected by polymerase chain reaction（PCR）at different time points and the changes also were compared along with the time.Results At 2h,the medium value and average value of plasma free DNA concentration were 20.00ng/mL and 63.59ng/mL（95%CI：30.26-96.92ng/mL）respectively,while at 6hthey were 12.56ng/mL and 16.90ng/mL（95%CI：9.26-24.54ng/mL）and at 30 h they were 60.90ng/mL and 90.64ng/mL（95%CI：59.01-122.27ng/mL）respectively.In addition,they were higher at 2hand 30 hthan at 6h（P=0.003,P=0.000）obivously,but the difference was not statisitically significant at 2hand 30h（P=0.218）.Conclusion The whole blood should be immediately isolated after being collected.If the isolation time was prolonged,it may reduce the degradation of the free DNA.