Carslake H B, Pinchbeck G L, McGowan C M
Institute of Aging and Chronic Disease, Faculty of Health and Life Sciences, University of Liverpool, Neston, Wirral, UK.
Institute of Infection and Global Health, Faculty of Health and Life Sciences, University of Liverpool, Neston, Wirral, UK.
J Vet Intern Med. 2017 Mar;31(2):568-574. doi: 10.1111/jvim.14657. Epub 2017 Jan 26.
Many diagnostic tests for insulin dysregulation use reference intervals established with an insulin radioimmunoassay (RIA) that is no longer available. A chemiluminescent immunoassay (CLIA) is commonly used for the measurement of serum insulin concentration in clinical practice but requires further validation, especially at clinically relevant reference intervals.
To evaluate the CLIA for measurement of equine insulin and compare it to the previously validated, but now unavailable RIA.
Equine serum samples (n = 78) from clinical and experimental studies.
In this experimental study, performance of the CLIA was evaluated using standard variables, including comparison with the RIA. Continuous and binary outcomes were analyzed.
The CLIA showed good intra-assay (coefficient of variation [CV], 1.8-2.4%) and interassay (CV, 3-7.1%) precision. Acceptable recovery on dilution (100 ± 10%) was achieved only at dilutions <1:1. Recovery on addition was acceptable. Comparison of the CLIA and RIA showed strong positive correlation (r = 0.91-0.98), with fixed and proportional bias. At 3 diagnostic cutoffs, sensitivity of CLIA compared with RIA ranged from 67 to 100% and specificity from 96 to 100%.
The CLIA is a highly repeatable assay which is suitable for within- and between-horse comparisons. Dilution of high concentration samples should be performed with charcoal-stripped serum (CSS) and at the lowest dilution factor possible. At concentrations commonly used for diagnosis of insulin dysregulation (≤100 μIU/mL), results from the CLIA tend to be lower than from the RIA and should be interpreted accordingly. Further standardization of equine insulin assays is required.
许多用于胰岛素调节异常的诊断测试采用的参考区间是基于一种现已不再可用的胰岛素放射免疫分析（RIA）建立的。化学发光免疫分析（CLIA）在临床实践中常用于测定血清胰岛素浓度，但需要进一步验证，尤其是在临床相关参考区间方面。
评估CLIA用于测定马胰岛素的性能，并将其与先前经验证但现已不再可用的RIA进行比较。
来自临床和实验研究的马血清样本（n = 78）。
在这项实验研究中，使用标准变量评估CLIA的性能，包括与RIA进行比较。对连续和二元结果进行分析。
CLIA显示出良好的批内精密度（变异系数[CV]，1.8 - 2.4%）和批间精密度（CV，3 - 7.1%）。仅在稀释度<1:1时，稀释回收率达到可接受水平（100 ± 10%）。加样回收率可接受。CLIA与RIA的比较显示出强正相关（r = 0.91 - 0.98），存在固定偏差和比例偏差。在3个诊断临界值下，CLIA与RIA相比的灵敏度范围为67%至100%，特异性范围为96%至100%。
CLIA是一种高度可重复的检测方法，适用于马匹内部和马匹之间的比较。高浓度样本应使用活性炭处理血清（CSS）并以尽可能低的稀释倍数进行稀释。在用于诊断胰岛素调节异常的常用浓度（≤100 μIU/mL）下，CLIA的结果往往低于RIA，应据此进行解释。马胰岛素检测需要进一步标准化。
