Mordelet-Dambrine M, Baglin J Y, Roux A, Dusser D, Flouvat B, Huchon G
Ther Drug Monit. 1986;8(1):106-10. doi: 10.1097/00007691-198603000-00018.
Rate nephelometric inhibition immunoassay (NIIA) was used to determine 94 serum theophylline concentrations, and these results were compared with those obtained using high performance liquid chromatography (HPLC) as a reference method. The measurements obtained by the nephelometric method were, on the average, 20% higher than those obtained by the chromatographic method (p less than 0.001). The coefficient of variation of the nephelometric method was 12.3%, compared with 3.9% for the chromatographic reference method. In the group of subjects having a serum concentration of caffeine greater than or equal to 0.5 microgram ml-1, the difference in serum theophylline concentration found between NIIA and HPLC correlated with serum caffeine concentration (r = 0.3755, df = 46, p less than 0.01). NIIA theophylline concentration was 8.8 +/- 3.2 micrograms ml-1 in serum from six additional patients receiving theophylline 9.1 +/- 3.4 micrograms ml-1 after adding 10 micrograms caffeine (NS), and 13.1 +/- 3.5 micrograms ml-1 after adding 10 micrograms 1,3-dimethyluric acid (p less than 0.001). We conclude that (a) the results obtained by the NIIA method are more variable and consistently higher than those obtained by the HPLC method and (b) 1,3-dimethyluric acid (a caffeine and theophylline metabolite) is responsible for this overevaluation.
速率散射比浊抑制免疫测定法（NIIA）用于测定94份血清中的茶碱浓度，并将这些结果与采用高效液相色谱法（HPLC）作为参考方法所获得的结果进行比较。散射比浊法所测得的结果平均比色谱法所测得的结果高20%（p<0.001）。散射比浊法的变异系数为12.3%，而色谱参考方法的变异系数为3.9%。在血清咖啡因浓度大于或等于0.5微克/毫升的受试者组中，NIIA法与HPLC法之间测得的血清茶碱浓度差异与血清咖啡因浓度相关（r=0.3755，自由度=46，p<0.01）。另外6例接受茶碱治疗的患者，在加入10微克咖啡因后，血清中NIIA法测得的茶碱浓度为8.8±3.2微克/毫升，加入10微克1,3 - 二甲基尿酸后为9.1±3.4微克/毫升（无显著差异），加入10微克1,3 - 二甲基尿酸后为13.1±3.5微克/毫升（p<0.001）。我们得出结论：（a）NIIA法所获得的结果比HPLC法所获得的结果更具可变性且始终更高；（b）1,3 - 二甲基尿酸（一种咖啡因和茶碱的代谢产物）是造成这种高估的原因。
