Cancer Prevention Institute of California, Fremont, California, United States of America.
Stanford Cancer Institute, Stanford University School of Medicine, Stanford, California, United States of America.
PLoS One. 2018 Apr 11;13(4):e0195666. doi: 10.1371/journal.pone.0195666. eCollection 2018.
Circulating melatonin is a good candidate biomarker for studies of circadian rhythms and circadian disruption. However, epidemiologic studies on circulating melatonin are limited because melatonin is secreted at night, yet most epidemiologic studies collect blood during the day when melatonin levels are very low, and assays are lacking that are ultrasensitive to detect low levels of melatonin reliably.
To assess the performance of a refined radioimmunoassay in measuring morning melatonin among women.
We used morning serum samples from 47 postmenopausal women ages 48-80 years without a history of breast cancer who participated in the San Francisco Bay Area Breast Cancer Study, including 19 women who had duplicate measurements. The coefficient of variation (CV) and intraclass coefficient (ICC) were estimated using the random effect model.
Reproducibility for the assay was satisfactory, with a CV of 11.2% and an ICC of 98.9%; correlation between the replicate samples was also high (R = 0.96). In the 47 women, serum melatonin levels ranged from 0.6 to 62.6 pg/ml, with a median of 7.0 pg/ml.
Our results suggest that it is possible to reliably measure melatonin in postmenopausal women in morning serum samples in large epidemiologic studies to evaluate the role of melatonin in cancer etiology or prognosis.
循环褪黑素是研究昼夜节律和昼夜节律紊乱的一个很好的候选生物标志物。然而，由于褪黑素在夜间分泌，而大多数流行病学研究都是在白天采集血液，此时褪黑素水平非常低，并且缺乏超灵敏的检测方法来可靠地检测到低水平的褪黑素，因此关于循环褪黑素的流行病学研究有限。
评估一种改良放射免疫分析法在测量绝经后女性晨时褪黑素中的性能。
我们使用了来自 47 名年龄在 48-80 岁、无乳腺癌病史的绝经后女性的清晨血清样本，这些女性均参与了旧金山湾区乳腺癌研究，其中 19 名女性有重复测量值。使用随机效应模型估计变异系数 (CV) 和组内相关系数 (ICC)。
该检测方法的重现性良好，CV 为 11.2%，ICC 为 98.9%；重复样本之间的相关性也很高 (R = 0.96)。在这 47 名女性中，血清褪黑素水平范围为 0.6-62.6 pg/ml，中位数为 7.0 pg/ml。
我们的结果表明，在大型流行病学研究中，有可能在清晨血清样本中可靠地测量绝经后女性的褪黑素，以评估褪黑素在癌症病因或预后中的作用。
