不同稀释介质对化学发光免疫法检测血清游离前列腺特异性抗原结果的评估

目的　评估不同稀释介质、稀释倍数在罗氏和新产业两仪器上稀释测定游离前列腺特异性抗原（free prostate specific antigen，FPSA）的可行性。方法　选取2020 年7~12 月在南通市肿瘤医院检测血清FPSA 浓度在40~50ng/ml 的样本60 例为研究对象，运用化学发光免疫法稀释验证。根据罗氏仪器的检测上限，选取30 例FPSA 浓度为40~50ng/ml 的血清样本，在罗氏仪器上分别用罗氏稀释液、蒸馏水、生理盐水和低值混合血清进行2，4 和8 倍稀释验证。根据新产业仪器的检测上限选取30 例FPSA 浓度为40~50ng/ml 的血清样本，在新产业仪器上分别用蒸馏水、生理盐水和低值混合血清进行2，4 和8 倍稀释验证。对样本使用配对t 检验，比较不同稀释介质和稀释倍数稀释后FPSA 测定值与原倍值的差异，并计算两者的偏差。结果　FPSA 在罗氏仪器上使用罗氏稀释液、蒸馏水、生理盐水和低值混合血清按不同比例稀释后测定，测定值的偏倚分别为-33.92%~63.51%，-36.83%~133.0%，-44.82%~116.2% 和-33.0%~74.2%，其中罗氏稀释液和低值混合血清2 倍稀释后结果与原倍值比较差异无统计学意义（t=0.387，0.707，均P>0.05），其余稀释后测定值与原倍值差异均有统计学意义（罗氏稀释液4 和8 倍，t=2.33，3.364；蒸馏水2，4 和8 倍，t=2.072，3.898，6.619；生理盐水2，4 和8 倍，t=2.052，3.078，6.507；低值混合血清4 和8 倍，t=3.584，6.229，均P<0.05）。FPSA 在新产业仪器上使用蒸馏水、生理盐水和低值混合血清按不同比例稀释后测定，测定值偏倚分别为-32.14%~112.07%，-30.89% ～ 95.22% 和-31.85% ～ 112.7%，稀释后测定值与原倍值差异均有统计学意义（蒸馏水2，4 和8 倍，t=2.169，2.706，3.996； 生理盐水2，4 和8 倍，t=2.149，2.617，3.757； 低值混合血清2，4 和8 倍，t=2.058，2.932，4.639， 均P<0.05）。结论　对于超出检测上限的FPSA，罗氏仪器可用罗氏稀释液和低值混合血清进行2 倍稀释，而新产业仪器不宜进行稀释检测。

Result Evaluation of Serum Free Prostate Specific Antigen by Chemiluminescence Immunomethods in Different Dilution Media

Objective　To evalue the feasibility of dilution determination free prostate specific antigen（FPSA) on Roche and New Industry Instruments with different dilution media. Methods　The FPSA concentration in 40~50ng/ml were collected from 60 patients in Nantong Tumor Hospital from July 2020 to December 2020 and diluted verification by chemiluminescene method. According to the upper limit of Roche instrument, 30 serum samples with FPSA concentration of 40~50ng/ml were selected and diluted with Roche diluent, distilled water, normal saline and low value mixed serum for 2, 4 and 8 times respectively. According to the upper limit of New Industrial Instrument, 30 serum samples with FPSA concentration of 40~50ng/ml were selected and diluted with distilled water, normal saline and low value mixed serum for 2, 4 and 8 times respectively. After diluted FPSA with different dilution medium and dilution times, the two values were used to compare the difference between the measured value and the original value with paired t test. Results　FPSA was diluted with Roche diluent, distilled water, normal saline and low value mixed serum in different proportion, subsequently FPSA was measured in Roche. The bias of measured value were -33.92%~63.51%, -36.83%~133.0%, -44.82%~116.2% and -33.0%~74.2% ,respectively. There was no significant difference between the original value and the measured value in Roche diluent or low value mixed serum after 2 times dilution (t= 0.701, 0.485, all P>0.05), and the other diluted values were statistically significant(t=2.33, 3.364 with 4, 8 times Roche diluent; t=2.072, 3.898, 6.619 with 2, 4 and 8 times distilled water; t=2.052, 3.078, 6.507 with 2, 4 and 8 times normal saline, and t=3.584, 6.229 with 4 and 8 times low value mixed serum, all P <0.05). FPSA was diluted with distilled water, normal saline and low value mixed serum in different proportion, subsequently FPSA was measured in New Industrial Instrument.The bias of the measured value were -32.14%~112.07%, -30.89%~95.22% and -331.85%~112.7% ,respectively, and the difference between the measured value and the original value after dilution was statistically significant(t=2.169, 2.706, 3.996 with 2, 4 and 8 times distilled water;t=2.149, 2.617, 3.757 with 2, 4 and 8 times normal saline and t=2.058, 2.932, 4.639 with 2, 4 and 8 times low value mixed serum, all P <0.05). Conclusion　FPSA which exceed the upper limit of detection can be measured with 2 times Roche dilution or low value mixed serum in Roche, while FPSA can not be diluted to measure in New Industrial Instrument.