Bremner W J, Vitiello M V, Prinz P N
J Clin Endocrinol Metab. 1983 Jun;56(6):1278-81. doi: 10.1210/jcem-56-6-1278.
Previous studies concerning the relationship of serum testosterone levels to aging in normal men have yielded apparently inconsistent results. Studies performing blood sampling in the morning have often shown an age-related decrease in testosterone levels, while those using afternoon samples have failed to show such a decrease. These results suggested to us the possibility that the circadian rhythm in serum testosterone levels might be altered with normal aging in men. Hourly blood samples were obtained for 24 h from 17 young (mean age, 25.2 yr) and 12 old (mean age, 71 yr) healthy men. Total testosterone levels were measured by RIA. The circadian rhythm in serum testosterone levels found in normal young men was markedly attenuated or absent in healthy elderly men; the early morning rise in testosterone levels characteristic of young men was not present in old age. Mean testosterone levels for the entire 24-h day were lower in healthy old men than in young men. These results demonstrate a clear decrease in serum testosterone levels in healthy old men compared to those in young men and provide an explanation for the inability to demonstrate an age-related decline in testosterone levels in earlier studies using serum samples obtained in the afternoon.
先前关于正常男性血清睾酮水平与衰老关系的研究结果明显不一致。在早晨进行采血的研究常常显示睾酮水平随年龄增长而下降，而那些使用下午样本的研究则未能显示出这种下降。这些结果让我们想到一种可能性，即男性血清睾酮水平的昼夜节律可能会随着正常衰老而改变。我们从17名年轻（平均年龄25.2岁）和12名老年（平均年龄71岁）健康男性身上采集了24小时的每小时血样。用放射免疫分析法测定总睾酮水平。正常年轻男性中发现的血清睾酮水平昼夜节律在健康老年男性中明显减弱或消失；老年男性不存在年轻男性特有的清晨睾酮水平升高现象。健康老年男性24小时全天的平均睾酮水平低于年轻男性。这些结果表明，与年轻男性相比，健康老年男性的血清睾酮水平明显降低，并为早期使用下午采集的血清样本进行的研究未能证明睾酮水平随年龄下降提供了解释。
