Novel Algorithm for Free Testosterone Determination

描述（由申请方提供）：睾酮水平的测量对于男性和女性雄激素紊乱的诊断至关重要。循环睾酮主要与性激素结合球蛋白（SHBG）和白蛋白结合;只有未结合或游离部分具有生物活性。因此，在影响SHBG浓度的条件下，如衰老，肥胖和糖尿病，游离睾酮的测定是必要的，以获得雄激素状态的准确评估。目前用于测定游离睾酮的方法-平衡透析、超滤、示踪剂模拟方法和基于质量作用定律的算法的使用-遭受不精确或不准确的问题。平衡透析法，被广泛认为是参考方法，是劳动密集型和繁琐的，容易受到错误，由于示踪杂质，导致内分泌学会的专家小组得出结论，“......游离睾酮的计算是血浆中游离睾酮的最有用的估计。“因此，使用质量作用定律方程从总睾酮、SHBG和白蛋白浓度计算游离睾酮浓度的算法已被广泛使用。我们的初步数据表明，目前SHBG上均匀睾酮结合位点的模型-现存的质量作用定律方程的概念基础-是错误的，并且从现有的质量作用定律方程推导出的游离睾酮浓度与平衡透析测量的浓度有很大差异。由于可用方法的这些局限性，对于可以方便地应用于临床实践的测定游离睾酮浓度的准确方法存在巨大的未满足的需求。新的证据表明，睾酮与SHBG的结合符合一个封闭的Allostery模型（EAM）。基于睾酮与SHBG结合的新EAM模型，我们构建了一种计算游离睾酮水平的新算法，该算法与平衡透析确定的值具有良好的一致性。该I期SBIR申请旨在通过确定其精密度、准确度、功能灵敏度、试验内和试验间变异性以及特异性、稳定性和基质效应来表征新型算法的技术性能（目标1）。目的2将在算法中纳入SHB基因型，并将其应用于具有不同SHBG基因型的男性。目标3将描述该检测在年轻和老年男性和女性以及SHBG浓度改变的肥胖男性中的性能。第一阶段研究的产品将是一个受版权保护的经验证的算法，可作为一个独立的应用程序，医生可以下载到他们的个人电脑或手持设备上，在办公室甚至床边使用。一个跨学科的研究团队，强大的初步数据，以及符合FDA指南的验证计划将确保成功生成一个产品，该产品有相当大的未满足的需求，这将促进我们对睾酮与SHBG结合的理解。

DESCRIPTION (provided by applicant): The measurement of testosterone levels is central to the diagnosis of androgen disorders in men and women. Circulating testosterone is bound largely to sex hormone binding globulin (SHBG) and albumin; only the unbound or free fraction is biologically active. Therefore, in conditions that affect SHBG concentrations, such as aging, obesity, and diabetes, the determination of free testosterone is necessary to obtain an accurate assessment of androgen status. The current methods for the determination of free testosterone - equilibrium dialysis, ultrafiltration, tracer analog methods, and the use of algorithms based on the law-of-mass-action - suffer from problems of imprecision or inaccuracy. Equilibrium dialysis method, widely considered the reference method, is labor-intensive and cumbersome, and susceptible to errors due to tracer impurities, leading the Endocrine Society's Expert Panel to conclude that "...the calculation of free testosterone is the most useful estimate of free testosterone in plasma..." Therefore, algorithms for calculating free testosterone concentrations from total testosterone, SHBG and albumin concentrations using the law-of-mass-action equations have been used widely. Our preliminary data show that the current model of homogeneous testosterone binding sites on SHBG - the conceptual basis of the extant law-of-mass action equations - is erroneous, and that the free testosterone concentrations derived from the available law-of-mass action equations differ substantially from those measured by equilibrium dialysis.. Because of these limitations of the available methods, there is an enormous unmet need for an accurate method to determine free testosterone concentrations that can be applied conveniently in clinical practice. New evidence shows that testosterone's binding to SHBG conforms to an Ensemble Allostery Model (EAM). Based on this new EAM model of testosterone binding to SHBG, we have constructed a novel algorithm for calculating free testosterone levels that provides excellent conformity with values determined by equilibrium dialysis. This phase I SBIR application aims to characterize the technical performance of the novel algorithm by determining its precision, accuracy, functional sensitivity, intra- and inter-assay variation, and specificity, stability, and matrix effects (Aim 1). Aim 2 will incorporate SHB genotype in the algorithm and apply it to men with different SHBG genotypes. Aim 3 will characterize the performance of the assay in young and older men and women, and in obese men with alterations in SHBG concentrations. The product of the phase I studies will be a copyright-protected validated algorithm available as a stand-alone application that physicians can download on their personal computers or hand-held devices for use in their office or even on the bedside. An interdisciplinary team of investigators, strong preliminary data, and a validation plan that conforms to FDA guidance will assure the successful generation of a product for which there is considerable unmet need and which will advance our understanding of testosterone's binding to SHBG.