Long-term studies investigating hormone-dependent cancers and reproductive health often require prolonged frozen storage of serum which assumes that the steroid molecules and measurements are stable over that time. Previous studies of reproducibility of circulating steroids have relied upon flawed historical rather than contemporaneous controls. We measured serum testosterone (T), dihydrotestosterone (DHT), estradiol (E2) and estrone (E1) in 150 randomly selected serum samples by liquid chromatography-mass spectrometry (LC-MS) from men 70 years or older (mean age 77 years) in the CHAMP study. The original measurements in 2009 were repeated 10 years later using the identical serum aliquot (having undergone 2-4 freeze-thaw cycles in the interim) in 2019 together with another never-thawed aliquot of the same serum sample. The results of all three sets of measurements were evaluated by Passing-Bablok regression and Bland-Altman difference analysis. Serum androgens (T, DHT) and estrogens (E2, E1) measured by LC-MS display excellent reproducibility when stored for 10 years at -80 C without thawing. Serum T and DHT displayed high level of reproducibility across all three sets of measurements. Multiple freeze-thaw cycles over those storage conditions do not significantly affect serum T, DHT and E1 concentrations but produce a modest increase (21%) in serum E2 measurements.

中文翻译：

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长时间冷冻保存后，通过质谱分析男性的循环性类固醇测量具有很高的重复性。

长期研究激素依赖性癌症和生殖健康的研究通常需要长时间冷冻保存血清，前提是假定类固醇分子和测量值在这段时间内是稳定的。以前对循环类固醇可重复性的研究依靠的是有缺陷的历史对照，而不是同期对照。我们通过液相色谱-质谱法（LC-MS）从70岁以上（平均年龄77岁）的男性中随机抽取了150个血清样本，测量了血清睾丸激素（T），二氢睾丸酮（DHT），雌二醇（E2）和雌酮（E1） ）在CHAMP研究中。10年后，使用相同的血清等分试样（在此期间经历了2-4次冻融循环）和相同血清样品的另一份未融化的等分试样在10年后重复进行2009年的原始测量。通过Passing-Bablok回归和Bland-Altman差异分析来评估所有三组测量的结果。通过LC-MS测定的血清雄激素（T，DHT）和雌激素（E2，E1）在-80 C下保存10年而不融化时显示出优异的重现性。血清T和DHT在所有三组测量中均显示出高水平的重现性。在这些储存条件下进行多次冻融循环不会显着影响血清T，DHT和E1浓度，但会导致血清E2测量值的适度增加（21％）。血清T和DHT在所有三组测量中均显示出高水平的重现性。在这些储存条件下进行多次冻融循环不会显着影响血清T，DHT和E1浓度，但会导致血清E2测量值的适度增加（21％）。血清T和DHT在所有三组测量中均显示出高水平的重现性。在这些储存条件下进行多次冻融循环不会显着影响血清T，DHT和E1浓度，但会导致血清E2测量值的适度增加（21％）。