甲状腺激素放射免疫分析内质控的实验与思考

Study on the Internal Quality Control of Thyroid Hormones Assays in a Hospital Laboratory

目的 :探讨甲状腺激素T3 、T4、FT3 、FT4、TSH检测结果不稳定和各项目间的不匹配原因 ,以提高检测质量 ,为临床提供可信的报告。方法 :通过实验室内质控改进分离方法 ,对各类加样器及放免测定仪定期监测 ,放免指标采用零管结合率 (B0 )、非特异结合 (NSB)、有效剂量值 (ED2 0 、ED50 、ED80 )、平均批变异系数 (ABCV)、平均病人值和质控血清含量的Shewart质控图 ,免放法选用B0 、NSB、ED80 、ED50 、ED2 0 、标准点偏差、质控血清和平均病人值。结果 :通过随意选择 1 0批标本共 96 4例测定结果分析 ,有 1 5 4例项目之间不匹配占 1 6 % ,而方法和操作的误差仅占不匹配标本的 5 8% ,其中大多数为甲状腺激素的生化特性和临床表现。结论 :分离误差是造成随机误差最主要来源 ,应选择稳定性好的分离法 ,推进固相分离替代均相分离 ,平均病人值有补充质控血清的作用 ,它和内质控的各项参数组成实验结果偏移取舍指标 ,以去除因方法和操作引起的误差 ,余下的不匹配结果原因为临床甲状腺疾病特点。实验人员要从技术和临床角度来分析结果 ,沟通实验室与临床的联系 。

Objective With the aim of providing more reliable informations for clinical diagnosis, this study investigated the possible causes of the occasional instability of thyroid hormones (T 3、 T 4、 FT 3、 FT 4、 TSH) assays in this laboratory and tried to seek plausible explanation for some seemingly contradictory (mismatching) readings of the laboratory reports. Methods Regular monitoring and checks were enforced on laboratory equipments from sampling pipet to gamma-counters. Results of separation with PR reagent and solid-phase coated tube were compared for superiority (FT 3). Collected specimens were tested in monthly sets; this study consisted of 10 sets with total 964 specimens. Serum T 3、 T 4、 FT 3、 FT 4 levels were measured with RIA. For every hormone tested, values of parameters of the standard cure (B 0、 NSB、 a、 b、 r、 ED 20 、 ED 50 、 ED 80 、 ABCV) were recorded in detail, from which the QC (quality control) table was derived. For complementary sake, mean level in patients’ sera was noted along with the quality control sera. Shewart control chart was drawn for quick reference. Serum TSH levels were measured with IRMA; the parameters involved were: B 0、 NSB、 ED 80 、 ED 50 、 ED 20 、 standard point deviation. Results Among the 964 specimens tested, there were 154 specimens with seemingly contradictory (mismatching) results, of which, the majority ( n=145 ) were not errorneous and were compatible with the clinical manifestations of thyroid dysfunction other than plain simple hyper-or hypothyroidism. Only 9 (5.8% of the 154) were due to technical errors (defective technic in removing the supernatant n=7 , lipid blood separated with PR reagent n=2 ). Conclusion Faulty technic in separation is the main source of random error. From the data of this laboratory, we believe that solid-phase separation method is better than the conventional homogenous-phase separation method and is the preferred one. With meticulous adherence to standard laboratory procedures and with all readings in the QC table meeting the QC demands, majority of those seemingly contradictory values are correct and can be satisfactorily explained. The clinicians are better informed with our report.